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#1
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What size wiring for Central A/C compressor?
I'm running new electric in a friends basement and so far uncovered a
lot of bad wiring jobs, buried splice boxes, you name it. So now I noticed that the central A/C compressor is wired with 10 guage wire. I'm pretty sure its suppose to be 8 guage. And also the existing 10 guage wire is hooked up to a 40 A breaker, which of course is not right, its suppose to be a 30A breaker. So since everything is wide open now, I was wondering should I run new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton unit, and the plate says "Min circuit ampacity 24.4 amps" and it also says " Max fuse or ckt bkr 40A". Even if the unit has been running fine all these years, I'm wondering what happens down the road if it needs to be replaced with a new unit that needs more amperage. the existing 10 guage wire will not be sufficient I'm thinking. |
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#2
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What size wiring for Central A/C compressor?
On Mar 3, 8:22*pm, Mikepier wrote:
I'm running new electric in a friends basement and so far uncovered a lot of bad wiring jobs, buried splice boxes, you name it. *So now I noticed that the central A/C compressor is wired with 10 guage wire. I'm pretty sure its suppose to be 8 guage. And also the *existing 10 guage wire is hooked up to a 40 A breaker, which of course is not right, its suppose to be a 30A breaker. So since everything is wide *open now, I was wondering should I run new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton unit, and the plate says "Min circuit ampacity 24.4 amps" and it also says " Max fuse or ckt bkr 40A". Even if the unit has been running fine all these years, I'm wondering what happens down the road if it needs to be replaced with a new unit that needs more amperage. the existing 10 guage wire will not be sufficient I'm thinking. normally a new install like a replacement AC will get all new wring and service disvconnect. a new 8 gauge copper line with new disconnect by the compressor will see less voltage drop, a good thing. but new compressors will likely be more efficent and run with less current. if everything is open then this is the best time to upgrade, and if breaker space is available run a couple 20 amp lines to work boxes for future use if needed. I did that once and a few years later was glad I did  when we decided to install a new kitchen |
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#3
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What size wiring for Central A/C compressor?
On 3/3/2013 7:22 PM, Mikepier wrote:
I'm running new electric in a friends basement and so far uncovered a lot of bad wiring jobs, buried splice boxes, you name it. So now I noticed that the central A/C compressor is wired with 10 guage wire. I'm pretty sure its suppose to be 8 guage. And also the existing 10 guage wire is hooked up to a 40 A breaker, which of course is not right, its suppose to be a 30A breaker. So since everything is wide open now, I was wondering should I run new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton unit, and the plate says "Min circuit ampacity 24.4 amps" and it also says " Max fuse or ckt bkr 40A". Even if the unit has been running fine all these years, I'm wondering what happens down the road if it needs to be replaced with a new unit that needs more amperage. the existing 10 guage wire will not be sufficient I'm thinking. In The U.S., standard gauge copper wire for a 20 amp circuit is 12 gauge and 10 gauge for a 30 amp circuit. Below is a link to a chart for standard current ratings for home wiring. There are all sorts of different ratings for different insulation types, wire in free air, in conduit or buried but the chart shows what any electrician would go by if wiring a home. Aluminum wiring is usually one gauge size larger for the same current carrying capacity as copper. ^_^ http://www.cerrowire.com/ampacity-charts TDD |
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#4
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What size wiring for Central A/C compressor?
On Mar 3, 8:55*pm, wrote:
On Sun, 3 Mar 2013 17:22:54 -0800 (PST), Mikepier wrote: I'm running new electric in a friends basement and so far uncovered a lot of bad wiring jobs, buried splice boxes, you name it. *So now I noticed that the central A/C compressor is wired with 10 guage wire. I'm pretty sure its suppose to be 8 guage. And also the *existing 10 guage wire is hooked up to a 40 A breaker, which of course is not right, its suppose to be a 30A breaker. So since everything is wide *open now, I was wondering should I run new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton unit, and the plate says "Min circuit ampacity 24.4 amps" and it also says " Max fuse or ckt bkr 40A". Even if the unit has been running fine all these years, I'm wondering what happens down the road if it needs to be replaced with a new unit that needs more amperage. the existing 10 guage wire will not be sufficient I'm thinking. OK hold on to your hat. That label says max fuse or breaker 40a ... that is what you have It also says minimum circuit ampacity 24.4a so the wire can be 12 ga. You are larger than you have to be with 10ga. That is what happens in article 440. They know you need a big breaker to get the compressor going but the actually running current is much lower. If you look at 310.15 you will see #12 is actually rated at 25a,. The common axiom that 14ga = 15a, 12ga = 20a comes from 240(4)(D) where they build the 80% safety factor in. (it is actually the max breaker size) It does not apply on dedicated motor circuits Homeowners will keep plugging things in until the breaker trips, then unplug the clock. That label has it built in *already by the engineer. You will see that compressor actually runs more like 16-18a on a hot day. I understand what the article is saying, but at the very least, shouldn't the 10 guage wire be on a 30A breaker and not 40A? |
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#5
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What size wiring for Central A/C compressor?
On 3/3/13 8:46 PM, Mikepier wrote:
I understand what the article is saying, but at the very least, shouldn't the 10 guage wire be on a 30A breaker and not 40A? The rules are different for motors than on other things for what it's worth. Wire is supposed to be sized at 125% of the full load amperage shown on the appropriate chart. Overcurrent protection can be 175% of the value shown in the chart. One can go to the next larger size if the 175% calculation puts one in between standard fuse or breaker sizes. This might not apply directly to air conditioners but I think the code writer's reasoning is the same. |
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#6
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What size wiring for Central A/C compressor?
Mikepier wrote:
I'm running new electric in a friends basement and so far uncovered a lot of bad wiring jobs, buried splice boxes, you name it. So now I noticed that the central A/C compressor is wired with 10 guage wire. I'm pretty sure its suppose to be 8 guage. And also the existing 10 guage wire is hooked up to a 40 A breaker, which of course is not right, its suppose to be a 30A breaker. So since everything is wide open now, I was wondering should I run new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton unit, and the plate says "Min circuit ampacity 24.4 amps" and it also says " Max fuse or ckt bkr 40A". Even if the unit has been running fine all these years, I'm wondering what happens down the road if it needs to be replaced with a new unit that needs more amperage. the existing 10 guage wire will not be sufficient I'm thinking. I had a 3.5 ton installed. They used 10 gauge and 30 amp breaker. After reading data plate and measuring operating current I switched to 20 amp breaker. It's only drawing 6.5 Amps and no problems. Never hurts to use thicker wire. Greg |
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#7
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What size wiring for Central A/C compressor?
On 3/3/2013 9:46 PM, gregz wrote:
Mikepier wrote: I'm running new electric in a friends basement and so far uncovered a lot of bad wiring jobs, buried splice boxes, you name it. So now I noticed that the central A/C compressor is wired with 10 guage wire. I'm pretty sure its suppose to be 8 guage. And also the existing 10 guage wire is hooked up to a 40 A breaker, which of course is not right, its suppose to be a 30A breaker. So since everything is wide open now, I was wondering should I run new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton unit, and the plate says "Min circuit ampacity 24.4 amps" and it also says " Max fuse or ckt bkr 40A". Even if the unit has been running fine all these years, I'm wondering what happens down the road if it needs to be replaced with a new unit that needs more amperage. the existing 10 guage wire will not be sufficient I'm thinking. I had a 3.5 ton installed. They used 10 gauge and 30 amp breaker. After reading data plate and measuring operating current I switched to 20 amp breaker. It's only drawing 6.5 Amps and no problems. Never hurts to use thicker wire. Greg The circuit breaker is meant to protect the wiring not necessarily the equipment which will normally have its own secondary protective devices. The 20 amp breaker won't harm anything but if there is a surge current greater than 20 amps from the AC unit starting on a hot day, you may get nuisance tripping of the breaker. O_o TDD |
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#8
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What size wiring for Central A/C compressor?
On Mar 3, 11:16*pm, The Daring Dufas the-daring-du...@stinky-
finger.net wrote: On 3/3/2013 9:46 PM, gregz wrote: Mikepier wrote: I'm running new electric in a friends basement and so far uncovered a lot of bad wiring jobs, buried splice boxes, you name it. *So now I noticed that the central A/C compressor is wired with 10 guage wire. I'm pretty sure its suppose to be 8 guage. And also the *existing 10 guage wire is hooked up to a 40 A breaker, which of course is not right, its suppose to be a 30A breaker. So since everything is wide *open now, I was wondering should I run new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton unit, and the plate says "Min circuit ampacity 24.4 amps" and it also says " Max fuse or ckt bkr 40A". Even if the unit has been running fine all these years, I'm wondering what happens down the road if it needs to be replaced with a new unit that needs more amperage. the existing 10 guage wire will not be sufficient I'm thinking. I had a 3.5 ton installed. They used 10 gauge and 30 amp breaker. After reading data plate and measuring operating current I switched to 20 amp breaker. It's only drawing 6.5 Amps and no problems. Never hurts to use thicker wire. Greg The circuit breaker is meant to protect the wiring not necessarily the equipment which will normally have its own secondary protective devices. The 20 amp breaker won't harm anything but if there is a surge current greater than 20 amps from the AC unit starting on a hot day, you may get nuisance tripping of the breaker. O_o TDD- Hide quoted text - - Show quoted text - A 20 amp breaker is less than the rated 24 amp min circuit capacity on the eqpt label. As others have stated, the existing 12 gauge wiring and 40 amp breaker are correct, meet code and no change is required. |
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#9
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What size wiring for Central A/C compressor?
On Mar 3, 8:57*pm, bob haller wrote:
On Mar 3, 8:22*pm, Mikepier wrote: I'm running new electric in a friends basement and so far uncovered a lot of bad wiring jobs, buried splice boxes, you name it. *So now I noticed that the central A/C compressor is wired with 10 guage wire. I'm pretty sure its suppose to be 8 guage. And also the *existing 10 guage wire is hooked up to a 40 A breaker, which of course is not right, its suppose to be a 30A breaker. So since everything is wide *open now, I was wondering should I run new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton unit, and the plate says "Min circuit ampacity 24.4 amps" and it also says " Max fuse or ckt bkr 40A". Even if the unit has been running fine all these years, I'm wondering what happens down the road if it needs to be replaced with a new unit that needs more amperage. the existing 10 guage wire will not be sufficient I'm thinking. normally a new install like a replacement AC will get all new wring and service disvconnect. Not around these parts. Unless the wiring is too small, deteriorated, etc. If not, then typically just the disconnect box on the exterior is changed. a new 8 gauge copper line with new disconnect by the compressor will see less voltage drop, a good thing. but new compressors will likely be more efficent and run with less current. if everything is open then this is the best time to upgrade, and if breaker space is available run a couple 20 amp lines to work boxes for future use if needed. I did that once and a few years later was glad I did when we decided to install a new kitchenWhy can't you just add those later, when and if needed? It's easier to just connect new wires to new breakers rather than install boxes, deal with splices, etc. |
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#10
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What size wiring for Central A/C compressor?
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#11
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What size wiring for Central A/C compressor?
On Mar 4, 7:50*am, The Daring Dufas the-daring-du...@stinky-
finger.net wrote: On 3/4/2013 6:13 AM, wrote: On Mar 3, 11:16 pm, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/3/2013 9:46 PM, gregz wrote: Mikepier wrote: I'm running new electric in a friends basement and so far uncovered a lot of bad wiring jobs, buried splice boxes, you name it. *So now I noticed that the central A/C compressor is wired with 10 guage wire. I'm pretty sure its suppose to be 8 guage. And also the *existing 10 guage wire is hooked up to a 40 A breaker, which of course is not right, its suppose to be a 30A breaker. So since everything is wide *open now, I was wondering should I run new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton unit, and the plate says "Min circuit ampacity 24.4 amps" and it also says " Max fuse or ckt bkr 40A". Even if the unit has been running fine all these years, I'm wondering what happens down the road if it needs to be replaced with a new unit that needs more amperage. the existing 10 guage wire will not be sufficient I'm thinking. I had a 3.5 ton installed. They used 10 gauge and 30 amp breaker. After reading data plate and measuring operating current I switched to 20 amp breaker. It's only drawing 6.5 Amps and no problems. Never hurts to use thicker wire. Greg The circuit breaker is meant to protect the wiring not necessarily the equipment which will normally have its own secondary protective devices. The 20 amp breaker won't harm anything but if there is a surge current greater than 20 amps from the AC unit starting on a hot day, you may get nuisance tripping of the breaker. O_o TDD- Hide quoted text - - Show quoted text - A 20 amp breaker is less than the rated 24 amp min circuit capacity on the eqpt label. *As others have stated, the existing 12 gauge wiring and 40 amp breaker are correct, meet code and no change is required. Not around here. Every electrical inspector I know would reject a 12 gauge wired circuit with a 40 amp circuit breaker. Then they are not following the NEC and either they don't know what they are doing or that particualr AHJ has unusual requirements. A 40 amp circuit uses #8 copper NM/UF 60°C cable or #8 aluminum SE/USE 75°C cable. You're trying to apply the NEC rules for general purpose branch circuits to motor eqpt that is on a dedicated circuit with it's own over-current protection. As the Mike stated, the eqpt label says the minimum circuit ampacity is 24 Amps. That translates into 10 guage wire being fine. Actually, 12 would also meet it. It further states that a 40 amp breaker is the max allowed, which is what he has. Presumably any competent electrical inspector would read the eqpt label and follow it. An electrical inspector may require #6 aluminum be used depending on the jurisdiction's requirements which may be stricter than The NEC. Theoretically any AHJ could make up anything they want. But #6 for this 3 ton AC is nuts. This applies to "homes" not necessarily industry which will normally use different wiring methods and higher temperature insulated wiring. I've wired homes, businesses and industry for a living so I know a little about electrical wiring. Then you should know that what Mike has is perfectly fine. It exceeds the eqpt label, which is what governs here and it meets NEC. I've also worked in commercial sales of electrical products. The circuit breaker is meant to protect the wiring and should always be sized accordingly. You're ignoring the fact that the eqpt has it's own over-current protection. There are places that have no electrical inspection department and I suppose you can do whatever you want. I've worked in those areas too and seen extremely dangerous wiring that was quite scary. ^_^ TDD- Hide quoted text - - Show quoted text - What Mike has is not dangerous. Itfully meets or exceeds NEC in every regard. |
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#12
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What size wiring for Central A/C compressor?
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#13
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What size wiring for Central A/C compressor?
On Mar 4, 10:50*am, The Daring Dufas the-daring-du...@stinky-
finger.net wrote: On 3/4/2013 7:56 AM, wrote: On Mar 4, 7:50 am, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/4/2013 6:13 AM, wrote: On Mar 3, 11:16 pm, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/3/2013 9:46 PM, gregz wrote: Mikepier wrote: I'm running new electric in a friends basement and so far uncovered a lot of bad wiring jobs, buried splice boxes, you name it. *So now I noticed that the central A/C compressor is wired with 10 guage wire. I'm pretty sure its suppose to be 8 guage. And also the *existing 10 guage wire is hooked up to a 40 A breaker, which of course is not right, its suppose to be a 30A breaker. So since everything is wide *open now, I was wondering should I run new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton unit, and the plate says "Min circuit ampacity 24.4 amps" and it also says " Max fuse or ckt bkr 40A". Even if the unit has been running fine all these years, I'm wondering what happens down the road if it needs to be replaced with a new unit that needs more amperage. the existing 10 guage wire will not be sufficient I'm thinking. I had a 3.5 ton installed. They used 10 gauge and 30 amp breaker. After reading data plate and measuring operating current I switched to 20 amp breaker. It's only drawing 6.5 Amps and no problems. Never hurts to use thicker wire. Greg The circuit breaker is meant to protect the wiring not necessarily the equipment which will normally have its own secondary protective devices. The 20 amp breaker won't harm anything but if there is a surge current greater than 20 amps from the AC unit starting on a hot day, you may get nuisance tripping of the breaker. O_o TDD- Hide quoted text - - Show quoted text - A 20 amp breaker is less than the rated 24 amp min circuit capacity on the eqpt label. *As others have stated, the existing 12 gauge wiring and 40 amp breaker are correct, meet code and no change is required. Not around here. Every electrical inspector I know would reject a 12 gauge wired circuit with a 40 amp circuit breaker. Then they are not following the NEC and either they don't know what they are doing or that particualr AHJ has unusual requirements. A 40 amp circuit uses #8 copper NM/UF 60°C cable or #8 aluminum SE/USE 75°C cable. You're trying to apply the NEC rules for general purpose branch circuits to motor eqpt that is on a dedicated circuit with it's own over-current protection. *As the Mike stated, the eqpt label says the minimum circuit ampacity is 24 Amps. *That translates into 10 guage wire being fine. *Actually, 12 would also meet it. It further states that a 40 amp breaker is the max allowed, which is what he has. * Presumably any competent electrical inspector would read the eqpt label and follow it. An electrical inspector may require #6 aluminum be used depending on the jurisdiction's requirements which may be stricter than The NEC. Theoretically any AHJ could make up anything they want. *But #6 for this 3 ton AC is nuts. This applies to "homes" not necessarily industry which will normally use different wiring methods and higher temperature insulated wiring. I've wired homes, businesses and industry for a living so I know a little about electrical wiring. Then you should know that what Mike has is perfectly fine. It exceeds the eqpt label, which is what governs here and it meets NEC. I've also worked in commercial sales of electrical products. The circuit breaker is meant to protect the wiring and should always be sized accordingly. You're ignoring the fact that the eqpt has it's own over-current protection. There are places that have no electrical inspection department and I suppose you can do whatever you want. I've worked in those areas too and seen extremely dangerous wiring that was quite scary. ^_^ TDD- Hide quoted text - - Show quoted text - What Mike has is not dangerous. *Itfully *meets or exceeds NEC in every regard. I'm not going to argue with you over it except to tell you it would not pass inspection in my area. Then maybe you can tell us what rules the inspectors are following and where your area is, because it's entirely consistent with NEC. And it would pass inspection here, in NJ. Or do your inspectors just make stuff up as they go along? |
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#14
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What size wiring for Central A/C compressor?
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#15
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What size wiring for Central A/C compressor?
On Monday, March 4, 2013 11:50:42 AM UTC-5, The Daring Dufas wrote:
Everywhere I've worked followed the NEC even on U.S. installations overseas where The Army Corps of Engineers took care of inspections. Except where they conflict with the DIN. Usually you can go with what is most stringent, but sometimes the NEC and DIN conflict and can't both be met. |
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#16
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What size wiring for Central A/C compressor?
On Mar 4, 11:50*am, The Daring Dufas the-daring-du...@stinky-
finger.net wrote: On 3/4/2013 10:27 AM, wrote: On Mar 4, 10:50 am, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/4/2013 7:56 AM, wrote: On Mar 4, 7:50 am, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/4/2013 6:13 AM, wrote: On Mar 3, 11:16 pm, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/3/2013 9:46 PM, gregz wrote: Mikepier wrote: I'm running new electric in a friends basement and so far uncovered a lot of bad wiring jobs, buried splice boxes, you name it. *So now I noticed that the central A/C compressor is wired with 10 guage wire. I'm pretty sure its suppose to be 8 guage. And also the *existing 10 guage wire is hooked up to a 40 A breaker, which of course is not right, its suppose to be a 30A breaker. So since everything is wide *open now, I was wondering should I run new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton unit, and the plate says "Min circuit ampacity 24.4 amps" and it also says " Max fuse or ckt bkr 40A". Even if the unit has been running fine all these years, I'm wondering what happens down the road if it needs to be replaced with a new unit that needs more amperage. the existing 10 guage wire will not be sufficient I'm thinking. I had a 3.5 ton installed. They used 10 gauge and 30 amp breaker. After reading data plate and measuring operating current I switched to 20 amp breaker. It's only drawing 6.5 Amps and no problems. Never hurts to use thicker wire. Greg The circuit breaker is meant to protect the wiring not necessarily the equipment which will normally have its own secondary protective devices. The 20 amp breaker won't harm anything but if there is a surge current greater than 20 amps from the AC unit starting on a hot day, you may get nuisance tripping of the breaker. O_o TDD- Hide quoted text - - Show quoted text - A 20 amp breaker is less than the rated 24 amp min circuit capacity on the eqpt label. *As others have stated, the existing 12 gauge wiring and 40 amp breaker are correct, meet code and no change is required. Not around here. Every electrical inspector I know would reject a 12 gauge wired circuit with a 40 amp circuit breaker. Then they are not following the NEC and either they don't know what they are doing or that particualr AHJ has unusual requirements. A 40 amp circuit uses #8 copper NM/UF 60°C cable or #8 aluminum SE/USE 75°C cable.. You're trying to apply the NEC rules for general purpose branch circuits to motor eqpt that is on a dedicated circuit with it's own over-current protection. *As the Mike stated, the eqpt label says the minimum circuit ampacity is 24 Amps. *That translates into 10 guage wire being fine. *Actually, 12 would also meet it. It further states that a 40 amp breaker is the max allowed, which is what he has. * Presumably any competent electrical inspector would read the eqpt label and follow it. An electrical inspector may require #6 aluminum be used depending on the jurisdiction's requirements which may be stricter than The NEC. Theoretically any AHJ could make up anything they want. *But #6 for this 3 ton AC is nuts. This applies to "homes" not necessarily industry which will normally use different wiring methods and higher temperature insulated wiring. I've wired homes, businesses and industry for a living so I know a little about electrical wiring. Then you should know that what Mike has is perfectly fine. It exceeds the eqpt label, which is what governs here and it meets NEC. I've also worked in commercial sales of electrical products. The circuit breaker is meant to protect the wiring and should always be sized accordingly. You're ignoring the fact that the eqpt has it's own over-current protection. There are places that have no electrical inspection department and I suppose you can do whatever you want. I've worked in those areas too and seen extremely dangerous wiring that was quite scary. ^_^ TDD- Hide quoted text - - Show quoted text - What Mike has is not dangerous. *Itfully *meets or exceeds NEC in every regard. I'm not going to argue with you over it except to tell you it would not pass inspection in my area. Then maybe you can tell us what rules the inspectors are following and where your area is, because it's entirely consistent with NEC. *And it would pass inspection here, in NJ. *Or do your inspectors just make stuff up as they go along? Everywhere I've worked followed the NEC even on U.S. installations overseas where The Army Corps of Engineers took care of inspections. Then you should be able to cite for us the section of NEC that says the installation that Mikepier has is in violation. Reference please. All I know is from my own experience working on various jobs over four decades. Perhaps you have much more experience in the field of electrical work than I do but I can only refer to my own experience. I'm an electrical engineer. And gfretw has weighed in on the issue. I believe he's an electrician. And he said the same things I did, in particular that what Mike has is code compliant and does not need to be changed. Perhaps you are an experienced electrician in your city/state and know how things are done in your kingdom but from your post, it appears you follow different standards. I must contact my relatives in New Jersey and implore them to run, run like the wind! ^_^ TDD- Hide quoted text - - Show quoted text - We follow the NEC here. So show us where the NEC says we're wrong..... And until them, stop spreading FUD. There is absolutely nothing unsafe, dangerous or in violation of NEC in what Mike has. This is a common confusion. Your mistake is applying the rules for branch circuits for lights, receptacles, etc to HVAC eqpt. Different rules apply for obvious reasons and if you'd just take the time to read the NEC, you'll see that. |
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#17
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What size wiring for Central A/C compressor?
On Mon, 4 Mar 2013 03:46:05 +0000 (UTC), gregz
wrote: Mikepier wrote: I'm running new electric in a friends basement and so far uncovered a lot of bad wiring jobs, buried splice boxes, you name it. So now I noticed that the central A/C compressor is wired with 10 guage wire. I'm pretty sure its suppose to be 8 guage. And also the existing 10 guage wire is hooked up to a 40 A breaker, which of course is not right, its suppose to be a 30A breaker. So since everything is wide open now, I was wondering should I run new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton unit, and the plate says "Min circuit ampacity 24.4 amps" and it also says " Max fuse or ckt bkr 40A". Even if the unit has been running fine all these years, I'm wondering what happens down the road if it needs to be replaced with a new unit that needs more amperage. the existing 10 guage wire will not be sufficient I'm thinking. I had a 3.5 ton installed. They used 10 gauge and 30 amp breaker. After reading data plate and measuring operating current I switched to 20 amp breaker. It's only drawing 6.5 Amps and no problems. Never hurts to use thicker wire. If you figure a SEER of 12, 3.5T (42,000BTU/HR) is 3.5kW or 14.5A. To get to 6.5A you'd have to have a SEER of 27! Something's not adding up here. |
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#18
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What size wiring for Central A/C compressor?
"The Daring Dufas" wrote in message ... I'm not going to argue with you over it except to tell you it would not pass inspection in my area. I don't argue with inspectors either because they can call people who carry guns and handcuffs. ^_^ TDD Some areas fo the counrty do not exectally follow the NEC. Unless you have a very good reason and can show the inspector where he is mistaken, it is best to just do as they say. If you ever get on their bad side, they will really look over your work and try to find a reason to make you redo something. It doesn't mater about the gun and cuffs, but they can have the power cut off or not turned on in the first place. |
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#19
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What size wiring for Central A/C compressor?
On 3/4/2013 11:15 AM, TimR wrote:
On Monday, March 4, 2013 11:50:42 AM UTC-5, The Daring Dufas wrote: Everywhere I've worked followed the NEC even on U.S. installations overseas where The Army Corps of Engineers took care of inspections. Except where they conflict with the DIN. Usually you can go with what is most stringent, but sometimes the NEC and DIN conflict and can't both be met. My experience is with American protectorates where the facilities are the same as back home. ^_^ TDD |
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What size wiring for Central A/C compressor?
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What size wiring for Central A/C compressor?
On 3/4/2013 12:09 PM, Ralph Mowery wrote:
"The Daring Dufas" wrote in message ... I'm not going to argue with you over it except to tell you it would not pass inspection in my area. I don't argue with inspectors either because they can call people who carry guns and handcuffs. ^_^ TDD Some areas fo the counrty do not exectally follow the NEC. Unless you have a very good reason and can show the inspector where he is mistaken, it is best to just do as they say. If you ever get on their bad side, they will really look over your work and try to find a reason to make you redo something. It doesn't mater about the gun and cuffs, but they can have the power cut off or not turned on in the first place. I get along with the inspectors and since I know them and they know the quality of my work, they don't usually dig to deeply into it unless I insist in order to satisfy a customer who may have doubts. That is something they understand since they themselves worked in the field. In some places they actually have to use a stamp with their name and number for the department which can be seen inside breaker panel doors. ^_^ TDD |
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What size wiring for Central A/C compressor?
On 3/4/2013 12:50 PM, The Daring Dufas wrote:
.... base my assertions on practical experience where I've worked. It may be different where you did your electrical and HVAC work for a living. Perhaps the authorities interpret the NEC differently where you have done your professional electrical and HVAC work? .... Far more likely they apply the correct section of Code for the purpose at hand. It would be far better to reference the specific Code in question or even the controlling jurisdiction which would likely lead to being able to find the relevant Codes in play. I strongly suspect if that were done it would be found that the installation under discussion is compliant there as well. -- |
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What size wiring for Central A/C compressor?
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What size wiring for Central A/C compressor?
On Mar 4, 3:15*pm, wrote:
On Mon, 04 Mar 2013 12:50:54 -0600, The Daring Dufas wrote: How often do you deal with electrical and mechanical inspection services? I've done electrical and HVAC work for a living and I base my assertions on practical experience where I've worked. It may be different where you did your electrical and HVAC work for a living. Perhaps the authorities interpret the NEC differently where you have done your professional electrical and HVAC work? TDD I have been a certified, state licensed electrical inspector for about 20 years. Florida and we follow the NEC state wide, unaltered, except for requiring bonding of steel studs. I said before, this is a common question on the inspector tests and if you say 8ga on a 40a breaker for a motor circuit like this, you got that one wrong. Maybe your inspectors are not certified and it is just the mayor's nephew who learned his trade from the Time Life electrical wiring for dummies book. It's also possible that he's basing his experience on what's required by what he's used and had passed. Of course if you use 8 gauge where a minimum of 12 gauge or 10 gauge is required, it passes because it meets code. And the inspector isn't likely to say, BTW did you know that 12 was sufficient? So, he goes on thinking that 8 gauge is what is required for it to pass. Obviously there hasn't been any discussion with an inspector about the issue, otherwise he'd be able to give us the code section that the position is based on. He refuses to recognize that the code treats breaker requirements for general purpose branch circuits differently than it does for motors, AC eqpt, etc. |
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What size wiring for Central A/C compressor?
On Mar 4, 1:50*pm, The Daring Dufas the-daring-du...@stinky-
finger.net wrote: On 3/4/2013 11:47 AM, wrote: On Mar 4, 11:50 am, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/4/2013 10:27 AM, wrote: On Mar 4, 10:50 am, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/4/2013 7:56 AM, wrote: On Mar 4, 7:50 am, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/4/2013 6:13 AM, wrote: On Mar 3, 11:16 pm, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/3/2013 9:46 PM, gregz wrote: Mikepier wrote: I'm running new electric in a friends basement and so far uncovered a lot of bad wiring jobs, buried splice boxes, you name it. *So now I noticed that the central A/C compressor is wired with 10 guage wire. I'm pretty sure its suppose to be 8 guage. And also the *existing 10 guage wire is hooked up to a 40 A breaker, which of course is not right, its suppose to be a 30A breaker. So since everything is wide *open now, I was wondering should I run new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton unit, and the plate says "Min circuit ampacity 24.4 amps" and it also says " Max fuse or ckt bkr 40A". Even if the unit has been running fine all these years, I'm wondering what happens down the road if it needs to be replaced with a new unit that needs more amperage. the existing 10 guage wire will not be sufficient I'm thinking. I had a 3.5 ton installed. They used 10 gauge and 30 amp breaker. After reading data plate and measuring operating current I switched to 20 amp breaker. It's only drawing 6.5 Amps and no problems. Never hurts to use thicker wire. Greg The circuit breaker is meant to protect the wiring not necessarily the equipment which will normally have its own secondary protective devices. The 20 amp breaker won't harm anything but if there is a surge current greater than 20 amps from the AC unit starting on a hot day, you may get nuisance tripping of the breaker. O_o TDD- Hide quoted text - - Show quoted text - A 20 amp breaker is less than the rated 24 amp min circuit capacity on the eqpt label. *As others have stated, the existing 12 gauge wiring and 40 amp breaker are correct, meet code and no change is required. Not around here. Every electrical inspector I know would reject a 12 gauge wired circuit with a 40 amp circuit breaker. Then they are not following the NEC and either they don't know what they are doing or that particualr AHJ has unusual requirements.. A 40 amp circuit uses #8 copper NM/UF 60°C cable or #8 aluminum SE/USE 75°C cable. You're trying to apply the NEC rules for general purpose branch circuits to motor eqpt that is on a dedicated circuit with it's own over-current protection. *As the Mike stated, the eqpt label says the minimum circuit ampacity is 24 Amps. *That translates into 10 guage wire being fine. *Actually, 12 would also meet it. It further states that a 40 amp breaker is the max allowed, which is what he has. * Presumably any competent electrical inspector would read the eqpt label and follow it. An electrical inspector may require #6 aluminum be used depending on the jurisdiction's requirements which may be stricter than The NEC. Theoretically any AHJ could make up anything they want. *But #6 for this 3 ton AC is nuts. This applies to "homes" not necessarily industry which will normally use different wiring methods and higher temperature insulated wiring. I've wired homes, businesses and industry for a living so I know a little about electrical wiring. Then you should know that what Mike has is perfectly fine. It exceeds the eqpt label, which is what governs here and it meets NEC. I've also worked in commercial sales of electrical products. The circuit breaker is meant to protect the wiring and should always be sized accordingly. You're ignoring the fact that the eqpt has it's own over-current protection. There are places that have no electrical inspection department and I suppose you can do whatever you want. I've worked in those areas too and seen extremely dangerous wiring that was quite scary. ^_^ TDD- Hide quoted text - - Show quoted text - What Mike has is not dangerous. *Itfully *meets or exceeds NEC in every regard. I'm not going to argue with you over it except to tell you it would not pass inspection in my area. Then maybe you can tell us what rules the inspectors are following and where your area is, because it's entirely consistent with NEC. *And it would pass inspection here, in NJ. *Or do your inspectors just make stuff up as they go along? Everywhere I've worked followed the NEC even on U.S. installations overseas where The Army Corps of Engineers took care of inspections. Then you should be able to cite for us the section of NEC that says the installation that Mikepier has is in violation. Reference please. All I know is from my own experience working on various jobs over four decades. Perhaps you have much more experience in the field of electrical work than I do but I can only refer to my own experience. I'm an electrical engineer. *And gfretw has weighed in on the issue. *I believe he's an electrician. *And he said the same things I did, in particular that what Mike has is code compliant and does not need to be changed. Perhaps you are an experienced electrician in your city/state and know how things are done in your kingdom but from your post, it appears you follow different standards. I must contact my relatives in New Jersey and implore them to run, run like the wind! ^_^ TDD- Hide quoted text - - Show quoted text - We follow the NEC here. *So show us where the NEC says we're wrong..... * And until them, stop spreading FUD. There is absolutely nothing unsafe, dangerous or in violation of NEC in what Mike has. * This is a common confusion. Your mistake is applying the rules for branch circuits for lights, receptacles, etc to HVAC eqpt. *Different rules apply for obvious reasons and if you'd just take the time to read the NEC, you'll see that. How often do you deal with electrical and mechanical inspection services? I've done electrical and HVAC work for a living and I base my assertions on practical experience where I've worked. It may be different where you did your electrical and HVAC work for a living. Perhaps the authorities interpret the NEC differently where you have done your professional electrical and HVAC work? TDD- Hide quoted text - - Show quoted text - When you can give us the section of the NEC where you can conclude that there is something wrong with Mikepier's installation, under ANY interpretation, then we can discuss differing interpretations. If an inspector is going to fail it, then he should be able to tell you that per NEC section X.Y, it's not allowed. This isn't the first time this issue has come up. And the result is usually the same. You have some people thinking that the same rules for lights and receptacles under the NEC also apply to motors and AC equipment. They don't. I would hope that someone who installs that eqpt would understand the distinction. |
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What size wiring for Central A/C compressor?
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What size wiring for Central A/C compressor?
On Mar 4, 5:55*pm, The Daring Dufas the-daring-du...@stinky-
finger.net wrote: On 3/4/2013 3:27 PM, wrote: On Mar 4, 1:50 pm, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/4/2013 11:47 AM, wrote: On Mar 4, 11:50 am, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/4/2013 10:27 AM, wrote: On Mar 4, 10:50 am, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/4/2013 7:56 AM, wrote: On Mar 4, 7:50 am, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/4/2013 6:13 AM, wrote: On Mar 3, 11:16 pm, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/3/2013 9:46 PM, gregz wrote: Mikepier wrote: I'm running new electric in a friends basement and so far uncovered a lot of bad wiring jobs, buried splice boxes, you name it. *So now I noticed that the central A/C compressor is wired with 10 guage wire. I'm pretty sure its suppose to be 8 guage. And also the *existing 10 guage wire is hooked up to a 40 A breaker, which of course is not right, its suppose to be a 30A breaker. So since everything is wide *open now, I was wondering should I run new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton unit, and the plate says "Min circuit ampacity 24.4 amps" and it also says " Max fuse or ckt bkr 40A". Even if the unit has been running fine all these years, I'm wondering what happens down the road if it needs to be replaced with a new unit that needs more amperage. the existing 10 guage wire will not be sufficient I'm thinking. I had a 3.5 ton installed. They used 10 gauge and 30 amp breaker. After reading data plate and measuring operating current I switched to 20 amp breaker. It's only drawing 6.5 Amps and no problems. Never hurts to use thicker wire. Greg The circuit breaker is meant to protect the wiring not necessarily the equipment which will normally have its own secondary protective devices. The 20 amp breaker won't harm anything but if there is a surge current greater than 20 amps from the AC unit starting on a hot day, you may get nuisance tripping of the breaker. O_o TDD- Hide quoted text - - Show quoted text - A 20 amp breaker is less than the rated 24 amp min circuit capacity on the eqpt label. *As others have stated, the existing 12 gauge wiring and 40 amp breaker are correct, meet code and no change is required. Not around here. Every electrical inspector I know would reject a 12 gauge wired circuit with a 40 amp circuit breaker. Then they are not following the NEC and either they don't know what they are doing or that particualr AHJ has unusual requirements. A 40 amp circuit uses #8 copper NM/UF 60°C cable or #8 aluminum SE/USE 75°C cable. You're trying to apply the NEC rules for general purpose branch circuits to motor eqpt that is on a dedicated circuit with it's own over-current protection. *As the Mike stated, the eqpt label says the minimum circuit ampacity is 24 Amps. *That translates into 10 guage wire being fine. *Actually, 12 would also meet it.. It further states that a 40 amp breaker is the max allowed, which is what he has. * Presumably any competent electrical inspector would read the eqpt label and follow it. An electrical inspector may require #6 aluminum be used depending on the jurisdiction's requirements which may be stricter than The NEC. Theoretically any AHJ could make up anything they want. *But #6 for this 3 ton AC is nuts. This applies to "homes" not necessarily industry which will normally use different wiring methods and higher temperature insulated wiring.. I've wired homes, businesses and industry for a living so I know a little about electrical wiring. Then you should know that what Mike has is perfectly fine. It exceeds the eqpt label, which is what governs here and it meets NEC. I've also worked in commercial sales of electrical products. The circuit breaker is meant to protect the wiring and should always be sized accordingly. You're ignoring the fact that the eqpt has it's own over-current protection. There are places that have no electrical inspection department and I suppose you can do whatever you want. I've worked in those areas too and seen extremely dangerous wiring that was quite scary. ^_^ TDD- Hide quoted text - - Show quoted text - What Mike has is not dangerous. *Itfully *meets or exceeds NEC in every regard. I'm not going to argue with you over it except to tell you it would not pass inspection in my area. Then maybe you can tell us what rules the inspectors are following and where your area is, because it's entirely consistent with NEC. *And it would pass inspection here, in NJ. *Or do your inspectors just make stuff up as they go along? Everywhere I've worked followed the NEC even on U.S. installations overseas where The Army Corps of Engineers took care of inspections. Then you should be able to cite for us the section of NEC that says the installation that Mikepier has is in violation. Reference please. All I know is from my own experience working on various jobs over four decades. Perhaps you have much more experience in the field of electrical work than I do but I can only refer to my own experience. I'm an electrical engineer. *And gfretw has weighed in on the issue. *I believe he's an electrician. *And he said the same things I did, in particular that what Mike has is code compliant and does not need to be changed. Perhaps you are an experienced electrician in your city/state and know how things are done in your kingdom but from your post, it appears you follow different standards. I must contact my relatives in New Jersey and implore them to run, run like the wind! ^_^ TDD- Hide quoted text - - Show quoted text - We follow the NEC here. *So show us where the NEC says we're wrong..... * And until them, stop spreading FUD. There is absolutely nothing unsafe, dangerous or in violation of NEC in what Mike has. * This is a common confusion. Your mistake is applying the rules for branch circuits for lights, receptacles, etc to HVAC eqpt. *Different rules apply for obvious reasons and if you'd just take the time to read the NEC, you'll see that. How often do you deal with electrical and mechanical inspection services? I've done electrical and HVAC work for a living and I base my assertions on practical experience where I've worked. It may be different where you did your electrical and HVAC work for a living. Perhaps the authorities interpret the NEC differently where you have done your professional electrical and HVAC work? TDD- Hide quoted text - - Show quoted text - When you can give us the section of the NEC where you can conclude that there is something wrong with Mikepier's installation, *under ANY interpretation, then we can discuss differing interpretations. *If an inspector is going to fail it, then he should be able to tell you that per NEC section X.Y, it's not allowed. This isn't the first time this issue has come up. *And the result is usually the same. *You have some people thinking that the same rules for lights and receptacles under the NEC also apply to motors and AC equipment. * They don't. *I would hope that someone who installs that eqpt would understand the distinction. If you'll look at NEC Table 310-16 you will see the amp rating for wire size. It changes depending on the insulation on the wire. Every 40 amp circuit I've ever installed in a home using 60°C NM/UF cable has been #8 copper. If I install a 40 amp circuit in conduit using 90°C THHN/THWN insulated wire I'll use #10 copper. And if you look at that table, it shows that 12 gauge is OK for up to 25 amps. The nameplate on the AC eqpt Mike has says the minimum circuit ampacity is 24.4 amps. Therefore, 12 gauge meets the minimum requirement and is permitted. The problem comes when you then try to tie the breaker to be installed for that AC eqpt with the wire size and treat it like it was a water heater, or a receptacle circuit. It is not. The eqpt manufacturer's rating governs and it says that a breaker of 40A max is permitted. I don't usually run conduit in a home. The last 4 ton AC condensing unit I installed used #14 THHN/THWN copper in conduit. It was a 3ø unit that called for a 15 amp breaker. 15 amp breaker for a 4 ton AC? That ain't right. I have to install what I know the inspector will pass and the inspectors do look at the temperature rating of the wire and check if the circuit breaker is HACR rated if it's hooked to an AC condensing unit. I don't argue with the inspectors, you can if you wish. O_o TDD- Hide quoted text - - Show quoted text - It's not an issue of arguing with the inspectors. It's what the NEC says disagrees with what you say. And if an inspector fails something, he should be willing to tell you what part of the code it failed and why, without getting into an argument. Any inspector should know that motors are treated differently than resistive loads. Just do some googling. This whole issue has come up many times. Some homeowner or inspector raises the issue of the breaker for an AC being larger than would normally be permitted for a light circuit, etc. that uses a given wire gauge. Or some home inspector flags it. Then a lot of discussion follows and the folks most knowledgable about the actual issues and code say it's perfectly normal. In this case, you have gfretw, an actual electrical inspector, telling you how it works and that what Mike has is code compliant. |
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What size wiring for Central A/C compressor?
On Mar 4, 5:55*pm, The Daring Dufas the-daring-du...@stinky-
finger.net wrote: On 3/4/2013 3:27 PM, wrote: On Mar 4, 1:50 pm, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/4/2013 11:47 AM, wrote: On Mar 4, 11:50 am, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/4/2013 10:27 AM, wrote: On Mar 4, 10:50 am, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/4/2013 7:56 AM, wrote: On Mar 4, 7:50 am, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/4/2013 6:13 AM, wrote: On Mar 3, 11:16 pm, The Daring Dufas the-daring-du...@stinky- finger.net wrote: On 3/3/2013 9:46 PM, gregz wrote: Mikepier wrote: I'm running new electric in a friends basement and so far uncovered a lot of bad wiring jobs, buried splice boxes, you name it. *So now I noticed that the central A/C compressor is wired with 10 guage wire. I'm pretty sure its suppose to be 8 guage. And also the *existing 10 guage wire is hooked up to a 40 A breaker, which of course is not right, its suppose to be a 30A breaker. So since everything is wide *open now, I was wondering should I run new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton unit, and the plate says "Min circuit ampacity 24.4 amps" and it also says " Max fuse or ckt bkr 40A". Even if the unit has been running fine all these years, I'm wondering what happens down the road if it needs to be replaced with a new unit that needs more amperage. the existing 10 guage wire will not be sufficient I'm thinking. I had a 3.5 ton installed. They used 10 gauge and 30 amp breaker. After reading data plate and measuring operating current I switched to 20 amp breaker. It's only drawing 6.5 Amps and no problems. Never hurts to use thicker wire. Greg The circuit breaker is meant to protect the wiring not necessarily the equipment which will normally have its own secondary protective devices. The 20 amp breaker won't harm anything but if there is a surge current greater than 20 amps from the AC unit starting on a hot day, you may get nuisance tripping of the breaker. O_o TDD- Hide quoted text - - Show quoted text - A 20 amp breaker is less than the rated 24 amp min circuit capacity on the eqpt label. *As others have stated, the existing 12 gauge wiring and 40 amp breaker are correct, meet code and no change is required. Not around here. Every electrical inspector I know would reject a 12 gauge wired circuit with a 40 amp circuit breaker. Then they are not following the NEC and either they don't know what they are doing or that particualr AHJ has unusual requirements. A 40 amp circuit uses #8 copper NM/UF 60°C cable or #8 aluminum SE/USE 75°C cable. You're trying to apply the NEC rules for general purpose branch circuits to motor eqpt that is on a dedicated circuit with it's own over-current protection. *As the Mike stated, the eqpt label says the minimum circuit ampacity is 24 Amps. *That translates into 10 guage wire being fine. *Actually, 12 would also meet it.. It further states that a 40 amp breaker is the max allowed, which is what he has. * Presumably any competent electrical inspector would read the eqpt label and follow it. An electrical inspector may require #6 aluminum be used depending on the jurisdiction's requirements which may be stricter than The NEC. Theoretically any AHJ could make up anything they want. *But #6 for this 3 ton AC is nuts. This applies to "homes" not necessarily industry which will normally use different wiring methods and higher temperature insulated wiring.. I've wired homes, businesses and industry for a living so I know a little about electrical wiring. Then you should know that what Mike has is perfectly fine. It exceeds the eqpt label, which is what governs here and it meets NEC. I've also worked in commercial sales of electrical products. The circuit breaker is meant to protect the wiring and should always be sized accordingly. You're ignoring the fact that the eqpt has it's own over-current protection. There are places that have no electrical inspection department and I suppose you can do whatever you want. I've worked in those areas too and seen extremely dangerous wiring that was quite scary. ^_^ TDD- Hide quoted text - - Show quoted text - What Mike has is not dangerous. *Itfully *meets or exceeds NEC in every regard. I'm not going to argue with you over it except to tell you it would not pass inspection in my area. Then maybe you can tell us what rules the inspectors are following and where your area is, because it's entirely consistent with NEC. *And it would pass inspection here, in NJ. *Or do your inspectors just make stuff up as they go along? Everywhere I've worked followed the NEC even on U.S. installations overseas where The Army Corps of Engineers took care of inspections. Then you should be able to cite for us the section of NEC that says the installation that Mikepier has is in violation. Reference please. All I know is from my own experience working on various jobs over four decades. Perhaps you have much more experience in the field of electrical work than I do but I can only refer to my own experience. I'm an electrical engineer. *And gfretw has weighed in on the issue. *I believe he's an electrician. *And he said the same things I did, in particular that what Mike has is code compliant and does not need to be changed. Perhaps you are an experienced electrician in your city/state and know how things are done in your kingdom but from your post, it appears you follow different standards. I must contact my relatives in New Jersey and implore them to run, run like the wind! ^_^ TDD- Hide quoted text - - Show quoted text - We follow the NEC here. *So show us where the NEC says we're wrong..... * And until them, stop spreading FUD. There is absolutely nothing unsafe, dangerous or in violation of NEC in what Mike has. * This is a common confusion. Your mistake is applying the rules for branch circuits for lights, receptacles, etc to HVAC eqpt. *Different rules apply for obvious reasons and if you'd just take the time to read the NEC, you'll see that. How often do you deal with electrical and mechanical inspection services? I've done electrical and HVAC work for a living and I base my assertions on practical experience where I've worked. It may be different where you did your electrical and HVAC work for a living. Perhaps the authorities interpret the NEC differently where you have done your professional electrical and HVAC work? TDD- Hide quoted text - - Show quoted text - When you can give us the section of the NEC where you can conclude that there is something wrong with Mikepier's installation, *under ANY interpretation, then we can discuss differing interpretations. *If an inspector is going to fail it, then he should be able to tell you that per NEC section X.Y, it's not allowed. This isn't the first time this issue has come up. *And the result is usually the same. *You have some people thinking that the same rules for lights and receptacles under the NEC also apply to motors and AC equipment. * They don't. *I would hope that someone who installs that eqpt would understand the distinction. If you'll look at NEC Table 310-16 you will see the amp rating for wire size. It changes depending on the insulation on the wire. Every 40 amp circuit I've ever installed in a home using 60°C NM/UF cable has been #8 copper. If I install a 40 amp circuit in conduit using 90°C THHN/THWN insulated wire I'll use #10 copper. I don't usually run conduit in a home. The last 4 ton AC condensing unit I installed used #14 THHN/THWN copper in conduit. It was a 3ø unit that called for a 15 amp breaker. I have to install what I know the inspector will pass and the inspectors do look at the temperature rating of the wire and check if the circuit breaker is HACR rated if it's hooked to an AC condensing unit. I don't argue with the inspectors, you can if you wish. O_o TDD- Hide quoted text - - Show quoted text - This is interesting stuff guys. I never knew there were a different set of codes for motors and A/C's. I'll leave the existing wiring for now. What I'll do is run a drag line in the ceiling joists so if i ever had to run another line, I can do it easily by pulling the new wire attached to the drag line. I have another question regarding central Vac systems wiring requirements. Please see upcoming seperate post. |
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What size wiring for Central A/C compressor?
wrote:
On Mon, 4 Mar 2013 03:46:05 +0000 (UTC), gregz wrote: Mikepier wrote: I'm running new electric in a friends basement and so far uncovered a lot of bad wiring jobs, buried splice boxes, you name it. So now I noticed that the central A/C compressor is wired with 10 guage wire. I'm pretty sure its suppose to be 8 guage. And also the existing 10 guage wire is hooked up to a 40 A breaker, which of course is not right, its suppose to be a 30A breaker. So since everything is wide open now, I was wondering should I run new 8 guage wire to the A/C? The unit is a Lennox, I beleive a 3 ton unit, and the plate says "Min circuit ampacity 24.4 amps" and it also says " Max fuse or ckt bkr 40A". Even if the unit has been running fine all these years, I'm wondering what happens down the road if it needs to be replaced with a new unit that needs more amperage. the existing 10 guage wire will not be sufficient I'm thinking. I had a 3.5 ton installed. They used 10 gauge and 30 amp breaker. After reading data plate and measuring operating current I switched to 20 amp breaker. It's only drawing 6.5 Amps and no problems. Never hurts to use thicker wire. If you figure a SEER of 12, 3.5T (42,000BTU/HR) is 3.5kW or 14.5A. To get to 6.5A you'd have to have a SEER of 27! Something's not adding up here. Right. It's pretty cold outside ! A couple of things. My memory is bad. The unit is in fact 2.5 tons. The installer quoted price for 3 ton unit ! Gsc130301a goodman. 13.7 minimum amp Max fuse amps 20 Compressor 9.7 amp 1.5 hp fan. The reading have been stable last 2-3 summers. 6.5 amp draw. Could low r22 cause reduced reading ? Im happy with the performance, low bills. I even drop the temp down to 68 degrees in summer nights. Greg |
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What size wiring for Central A/C compressor?
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What size wiring for Central A/C compressor?
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What size wiring for Central A/C compressor?
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What size wiring for Central A/C compressor?
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What size wiring for Central A/C compressor?
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#36
Posted to alt.home.repair
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What size wiring for Central A/C compressor?
The Daring Dufas wrote:
If gfretw was the inspector in charge I would do what he said but I have to go by what the inspectors here and now require. I also go by the manufacturers requirements unless they clash with the inspector who has final say. The city here actually has stricter guidelines in some areas than the NEC. Here, they want the circuit and wire gauge to match no matter what the load is with the only difference being that HACR rated breakers be used on AC and refrigeration units. Understand that the temperature rating of the insulation also determines the amp carrying specification of the wiring for both copper and aluminum. ^_^ I replaced my 3-ton a/c unit after its 12-year old predecessor croaked as a result of Hurricane Yikes*. The chap who replaced it said I could also swap out the 40-amp breaker with a 30-amp one inasmuch as more modern units, mine included, were more efficient and drew less power. Makes sense since the original a/c unit was a builder model from the 1960's. The compressor unit, no doubt, had been replaced, maybe more than once, before I bought the house. But nobody every fiddled with changing the circuit breaker. ---------------- * The fellow who did the work is a Guatamalan off-the-books a/c technician. Evidently he is part of a co-national underground network of repair people in that he knew a guy who obtains and reconditions a/c units, some from insurance companies after house fires. Anyway, the unit he chose was a two-year old Trane, and the unit has been working swell for the past four years. The whole business, compressor unit, installation, vacuuming, and recharge cost $750. One point is this: If you can find ONE immigrant tradesman, you've got access, probably, to lots of others (roofers, sewer replacement, concrete work, etc.). No, they're not bonded, insured, and so forth, but the proof is in the pudding. If the job works, you're good. Besides, I know where Lewis, the guy who did the work, lives - next door to my son - and Lewis knows I have a gun. Feel free to disagree, but this technique works for me. |
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#37
Posted to alt.home.repair
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What size wiring for Central A/C compressor?
On 3/5/2013 2:45 PM, HeyBub wrote:
The Daring Dufas wrote: If gfretw was the inspector in charge I would do what he said but I have to go by what the inspectors here and now require. I also go by the manufacturers requirements unless they clash with the inspector who has final say. The city here actually has stricter guidelines in some areas than the NEC. Here, they want the circuit and wire gauge to match no matter what the load is with the only difference being that HACR rated breakers be used on AC and refrigeration units. Understand that the temperature rating of the insulation also determines the amp carrying specification of the wiring for both copper and aluminum. ^_^ I replaced my 3-ton a/c unit after its 12-year old predecessor croaked as a result of Hurricane Yikes*. The chap who replaced it said I could also swap out the 40-amp breaker with a 30-amp one inasmuch as more modern units, mine included, were more efficient and drew less power. Makes sense since the original a/c unit was a builder model from the 1960's. The compressor unit, no doubt, had been replaced, maybe more than once, before I bought the house. But nobody every fiddled with changing the circuit breaker. ---------------- * The fellow who did the work is a Guatamalan off-the-books a/c technician. Evidently he is part of a co-national underground network of repair people in that he knew a guy who obtains and reconditions a/c units, some from insurance companies after house fires. Anyway, the unit he chose was a two-year old Trane, and the unit has been working swell for the past four years. The whole business, compressor unit, installation, vacuuming, and recharge cost $750. One point is this: If you can find ONE immigrant tradesman, you've got access, probably, to lots of others (roofers, sewer replacement, concrete work, etc.). No, they're not bonded, insured, and so forth, but the proof is in the pudding. If the job works, you're good. Besides, I know where Lewis, the guy who did the work, lives - next door to my son - and Lewis knows I have a gun. Feel free to disagree, but this technique works for me. Whatever works. I try to avoid government involvement in business whenever I can because it tends to increase the cost of everything but at the same time I'll do quality work and not slipshod crap which gives folks a reason to complain to a government puke. ^_^ TDD |
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#38
Posted to alt.home.repair
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What size wiring for Central A/C compressor?
What about the outside disconnect? It is just simply a "pull-out" type
disconnect, no fuses, just solid copper buss bars. I don't see any rating for it. How do I know it's rating? Or are all these type of disconnects just a standard rating? |
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#39
Posted to alt.home.repair
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What size wiring for Central A/C compressor?
On 3/5/2013 7:20 PM, Mikepier wrote:
What about the outside disconnect? It is just simply a "pull-out" type disconnect, no fuses, just solid copper buss bars. I don't see any rating for it. How do I know it's rating? Or are all these type of disconnects just a standard rating? I personally don't like the pull out disconnects because they can corrode from mishandling and pranksters can make off with the pull out. I use the Square D dummy breaker in a rain proof box. It looks like a standard Square D QO breaker but with no over current protection and a real circuit breaker will actually snap-in in its place. ^_^ http://preview.tinyurl.com/afjtpkh http://preview.tinyurl.com/bav4wkr TDD |
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#40
Posted to alt.home.repair
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What size wiring for Central A/C compressor?
The Daring Dufas wrote:
On 3/5/2013 7:20 PM, Mikepier wrote: What about the outside disconnect? It is just simply a "pull-out" type disconnect, no fuses, just solid copper buss bars. I don't see any rating for it. How do I know it's rating? Or are all these type of disconnects just a standard rating? I personally don't like the pull out disconnects because they can corrode from mishandling and pranksters can make off with the pull out. I use the Square D dummy breaker in a rain proof box. It looks like a standard Square D QO breaker but with no over current protection and a real circuit breaker will actually snap-in in its place. ^_^ As for pranksters, my disconnect has a a padlock, the key to which is kept in the main circuit-breaker box (which also has a padlock). |
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