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#1
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subpanels and grounding
(a slight followup first for those of you who were reading my subpanel
thread a few days ago) I decided not to use the 100amp box. I found a proper 12 postion subpanel at the borg. I've already started the install. I'm using 3/4" emt with #6 wire, 60 amp breaker in the main box, a 75' run, all indoors. Originally, I was going to run four wires through the 3/4" pipe (red, white, black, and green). The electrical guy at home depot said that if you're using emt, you don't need the separate ground wire since the boxes are grounded together through the emt. Does this sound right? So far, I've run the other three. It's a bit of a long run so I'd rather not do the fourth wire. brian |
#2
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On 6 Jun 2005 09:03:43 -0700, brianlanning wrote:
(a slight followup first for those of you who were reading my subpanel thread a few days ago) I decided not to use the 100amp box. I found a proper 12 postion subpanel at the borg. I've already started the install. I'm using 3/4" emt with #6 wire, 60 amp breaker in the main box, a 75' run, all indoors. Are you certain you won't exceed the fill limit (or need to derate the conductors) on the conduit with three current-carrying #6 conductors? Originally, I was going to run four wires through the 3/4" pipe (red, white, black, and green). The electrical guy at home depot said that if you're using emt, you don't need the separate ground wire since the boxes are grounded together through the emt. Does this sound right? So far, I've run the other three. It's a bit of a long run so I'd rather not do the fourth wire. Check the NEC. I think you need the ground wire. And bonding at both ends of the conduit. -- Art Greenberg artg AT eclipse DOT net |
#3
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"brianlanning" wrote in message oups.com... (a slight followup first for those of you who were reading my subpanel thread a few days ago) I decided not to use the 100amp box. I found a proper 12 postion subpanel at the borg. I've already started the install. I'm using 3/4" emt with #6 wire, 60 amp breaker in the main box, a 75' run, all indoors. Originally, I was going to run four wires through the 3/4" pipe (red, white, black, and green). The electrical guy at home depot said that if you're using emt, you don't need the separate ground wire since the boxes are grounded together through the emt. Does this sound right? No, but it does sound like you should let someone who knows what he is doing (such as an electrician) do the job. Jim |
#4
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In article .com, "brianlanning" wrote:
(a slight followup first for those of you who were reading my subpanel thread a few days ago) I decided not to use the 100amp box. I found a proper 12 postion subpanel at the borg. I've already started the install. I'm using 3/4" emt with #6 wire, 60 amp breaker in the main box, a 75' run, all indoors. If you're using THHN or THWN conductors, that's ok. If TW, THW, RHW, or RHH, you have a code violation already. They're probably THHN, but you oughta check just to make sure. It's stamped on the insulation. Originally, I was going to run four wires through the 3/4" pipe (red, white, black, and green). The electrical guy at home depot said that if you're using emt, you don't need the separate ground wire since the boxes are grounded together through the emt. Does this sound right? The NEC _explicitly_permits_ the use of EMT as an equipment grounding conductor. [Article 250-91(b)] So far, I've run the other three. It's a bit of a long run so I'd rather not do the fourth wire. -- Regards, Doug Miller (alphageek at milmac dot com) Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time? |
#5
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Even if the EMT is allowed to be the grounding conductor, I'd run a
copper wire anyway, especially for a circuit feeding a subpanel. |
#6
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If you're using THHN or THWN conductors, that's ok. If TW, THW, RHW, or RHH,
you have a code violation already. They're probably THHN, but you oughta check just to make sure. It's stamped on the insulation. I believe it's THHN. He had a code book there and looked up the types, gauge, and conduit sizes on the spot. The NEC _explicitly_permits_ the use of EMT as an equipment grounding conductor. [Article 250-91(b)] Thanks, this is what I was looking for. brian |
#7
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Are you certain you won't exceed the fill limit (or need to derate the
conductors) on the conduit with three current-carrying #6 conductors? Those sizes came from a NEC code book they had there in the store. brian |
#8
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On 6 Jun 2005 13:49:20 -0700, "brianlanning"
wrote: If you're using THHN or THWN conductors, that's ok. If TW, THW, RHW, or RHH, you have a code violation already. They're probably THHN, but you oughta check just to make sure. It's stamped on the insulation. I believe it's THHN. He had a code book there and looked up the types, gauge, and conduit sizes on the spot. The NEC _explicitly_permits_ the use of EMT as an equipment grounding conductor. [Article 250-91(b)] Thanks, this is what I was looking for. There is one other thing to consider and that is three 6s in 3/4" conduit, even thought permitted, can be a tough pull (especially over 75'. Can it hurt you to put in 1" instead? You'll probably have to use preformed elbows. -- LRod Master Woodbutcher and seasoned termite Shamelessly whoring my website since 1999 http://www.woodbutcher.net Proud participant of rec.woodworking since February, 1997 |
#9
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brianlanning wrote:
The electrical guy at home depot said that if you're using emt, you don't need the separate ground wire since the boxes are grounded together through the emt. Does this sound right? Nice try but no cigar. Not in my world anyway. Lew |
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Lew Hodgett writes:
brianlanning wrote: The electrical guy at home depot said that if you're using emt, you don't need the separate ground wire since the boxes are grounded together through the emt. Does this sound right? Nice try but no cigar. Not in my world anyway. And what world is that? See the NEC. EMT is explicitly allowed as the grounding conductor. BX and armoured cable are explicitly disallowed (as of 1999?). If I were doing it, using the EMT as the grounding means, I'd use compression fittings rather than setscrew. scott Lew |
#11
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It was tough. I finished it last night. I used 90 degree fittings
also which made it that much worse. Half way through the project, I started threading sections of emt as I assembled them. That made the job a lot easier. I didn't look at the price for 1" conduit. I know the 1 1/4" conduit I would have used for the #3 100amp wire was $15 for an 8' segment. That was three times more than the $5 for the 3/4". So I went with the 60 amp parts. If I had to do it again, I would buy the pipe bender. That tool would probably have been cheaper than the cost of all the fittings and it would have made pulling the wire easier. brian LRod wrote: On 6 Jun 2005 13:49:20 -0700, "brianlanning" wrote: There is one other thing to consider and that is three 6s in 3/4" conduit, even thought permitted, can be a tough pull (especially over 75'. Can it hurt you to put in 1" instead? You'll probably have to use preformed elbows. |
#12
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In article .com, "brianlanning" wrote:
It was tough. I finished it last night. I used 90 degree fittings also which made it that much worse. Half way through the project, I started threading sections of emt as I assembled them. Threading EMT is _explicitly_forbidden_ by the NEC. -- Regards, Doug Miller (alphageek at milmac dot com) Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time? |
#13
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On Tue, 07 Jun 2005 18:15:58 GMT, Doug Miller wrote:
In article .com, "brianlanning" wrote: It was tough. I finished it last night. I used 90 degree fittings also which made it that much worse. Half way through the project, I started threading sections of emt as I assembled them. Threading EMT is _explicitly_forbidden_ by the NEC. I didn't know you _could_ thread EMT, even if not forbidden from doing so? (side note: just how many groups do we cross paths in, Doug?) |
#14
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In article , Dave Hinz wrote:
On Tue, 07 Jun 2005 18:15:58 GMT, Doug Miller wrote: In article .com, "brianlanning" wrote: It was tough. I finished it last night. I used 90 degree fittings also which made it that much worse. Half way through the project, I started threading sections of emt as I assembled them. Threading EMT is _explicitly_forbidden_ by the NEC. I didn't know you _could_ thread EMT, even if not forbidden from doing so? I didn't either, actually.... not sure why anyone would try, since the walls are so thin. But it's there in the Code. (side note: just how many groups do we cross paths in, Doug?) At least two besides this one, I think. :-) -- Regards, Doug Miller (alphageek at milmac dot com) Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time? |
#15
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On Tue, 07 Jun 2005 18:15:58 GMT, Doug Miller wrote:
In article .com, "brianlanning" wrote: It was tough. I finished it last night. I used 90 degree fittings also which made it that much worse. Half way through the project, I started threading sections of emt as I assembled them. Threading EMT is _explicitly_forbidden_ by the NEC. I *think* he meant as in "threading a needle". Rather than pull the wires through a fully assembled conduit run, he's pushing the conduit sections onto the cable, one at a time. At least, that's what I think he meant. -- Art Greenberg artg AT eclipse DOT net |
#16
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On Tue, 07 Jun 2005 19:35:47 GMT, Art Greenberg
wrote: On Tue, 07 Jun 2005 18:15:58 GMT, Doug Miller wrote: In article .com, "brianlanning" wrote: It was tough. I finished it last night. I used 90 degree fittings also which made it that much worse. Half way through the project, I started threading sections of emt as I assembled them. Threading EMT is _explicitly_forbidden_ by the NEC. I *think* he meant as in "threading a needle". Rather than pull the wires through a fully assembled conduit run, he's pushing the conduit sections onto the cable, one at a time. At least, that's what I think he meant. I took it that way, too. -- LRod Master Woodbutcher and seasoned termite Shamelessly whoring my website since 1999 http://www.woodbutcher.net Proud participant of rec.woodworking since February, 1997 |
#17
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oops, I mean pushing wire throught he conduit, not cutting threads in
the ends. brian |
#18
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#19
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"brianlanning" wrote in message oups.com... Are you certain you won't exceed the fill limit (or need to derate the conductors) on the conduit with three current-carrying #6 conductors? Those sizes came from a NEC code book they had there in the store. brian Never use the minimum conduit size allowed by the NEC. It's not worth it. Also consider using boxes as pull points when you change direction and at reasonable intervals. |
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