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Electrical: when are loops at screw terminals allowed?
Hi,
I'm interested in when it is allowed (NEC) and advisable to make a connection in an electrical box of a wire to a screw terminal by looping the wire around and then using the free end for another connection. Here's what I think I know: 1) It is NOT allowed to do this with the hot or neutral conductors and the screw terminals on a device. Use pigtails. 2) It is allowed to do this with the EGC and the grounding screw of a metal box or strap. This is a good idea, because it makes a neater, tighter installation. So I think this only leaves the case of the EGC and the ground screw on a device. Is looping allowed here? Is it a good idea? Thanks, Wayne P.S. FWIW I'm just contemplating my three gang switch box and how to handle the 8 grounds (5 cables and 3 screw terminals). One option would be loop a ground around each of the 3 devices, and use a wire nut on the 5 ground wires. Another is to use 3 pigtails; joining the 8 ground wires would require splitting them into two groups and using two wire nuts with a jumper between them. |
#2
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If you are using a metal box, splice your grounds together and to the box.
Don't put them on switches. The neutral of a multiwire circuit (two hots sharing a neutral) cannot be dependent on a device, but if you are looping wire like you describe, it's not "Wayne Whitney" wrote in message ... Hi, I'm interested in when it is allowed (NEC) and advisable to make a connection in an electrical box of a wire to a screw terminal by looping the wire around and then using the free end for another connection. Here's what I think I know: 1) It is NOT allowed to do this with the hot or neutral conductors and the screw terminals on a device. Use pigtails. 2) It is allowed to do this with the EGC and the grounding screw of a metal box or strap. This is a good idea, because it makes a neater, tighter installation. So I think this only leaves the case of the EGC and the ground screw on a device. Is looping allowed here? Is it a good idea? Thanks, Wayne P.S. FWIW I'm just contemplating my three gang switch box and how to handle the 8 grounds (5 cables and 3 screw terminals). One option would be loop a ground around each of the 3 devices, and use a wire nut on the 5 ground wires. Another is to use 3 pigtails; joining the 8 ground wires would require splitting them into two groups and using two wire nuts with a jumper between them. |
#3
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Wayne Whitney writes:
Hi, I'm interested in when it is allowed (NEC) and advisable to make a connection in an electrical box of a wire to a screw terminal by looping the wire around and then using the free end for another connection. Here's what I think I know: 1) It is NOT allowed to do this with the hot or neutral conductors and the screw terminals on a device. Use pigtails. 2) It is allowed to do this with the EGC and the grounding screw of a metal box or strap. This is a good idea, because it makes a neater, tighter installation. So I think this only leaves the case of the EGC and the ground screw on a device. Is looping allowed here? Is it a good idea? Thanks, Wayne My electrician seems to love looping the hot wire from one switch to another in a 2-gang box. Is this fully against code or just not advisable? |
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#5
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On 2005-03-14, blueman wrote:
Could someone please explain to me then what is "illegal" about the "looping" that the OP is talking about? Maybe it isn't, maybe it is just considered a questionable practice by some (including some inspectors?). Wayne (the OP) |
#6
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OK, based on the comments so far, let me try to revise what I think I
know about looping a wire around a screw terminal (and continuing to another connection): 1) It is not advisable to do this with an insulated conductor, although I'm not too clear on the reasoning. One thing that is clear to me is that if this is done, the requisite 6" of conductor should be left before the first looped connection. 2) It is advisable to do this with the EGC and the grounding screw of a metal box or strap, because it makes a neater, tighter installation. So that still leaves me with the question of whether it is a good idea to do this with the EGC and the ground screw on a device. Specifically, for a light switch, I'm considering looping the EGC of the cable with the outbound switched hot around the ground screw of the switch that serves it. What's the downside? Thanks, Wayne |
#7
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As long as you remove a suffucuent length of insulation without nicking the
wire, it is hard to see ant downside. It should actully be very slightly preferable as the total resistance to the last device on the line will be slightly less. Each junction adds a little resistance. On Mon, 14 Mar 2005 11:52:01 -0600, Wayne Whitney wrote: OK, based on the comments so far, let me try to revise what I think I know about looping a wire around a screw terminal (and continuing to another connection): 1) It is not advisable to do this with an insulated conductor, although I'm not too clear on the reasoning. One thing that is clear to me is that if this is done, the requisite 6" of conductor should be left before the first looped connection. 2) It is advisable to do this with the EGC and the grounding screw of a metal box or strap, because it makes a neater, tighter installation. So that still leaves me with the question of whether it is a good idea to do this with the EGC and the ground screw on a device. Specifically, for a light switch, I'm considering looping the EGC of the cable with the outbound switched hot around the ground screw of the switch that serves it. What's the downside? Thanks, Wayne |
#8
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On Mon, 14 Mar 2005 02:25:37 GMT, blueman wrote:
Wayne Whitney writes: Hi, I'm interested in when it is allowed (NEC) and advisable to make a connection in an electrical box of a wire to a screw terminal by looping the wire around and then using the free end for another connection. Here's what I think I know: 1) It is NOT allowed to do this with the hot or neutral conductors and the screw terminals on a device. Use pigtails. 2) It is allowed to do this with the EGC and the grounding screw of a metal box or strap. This is a good idea, because it makes a neater, tighter installation. So I think this only leaves the case of the EGC and the ground screw on a device. Is looping allowed here? Is it a good idea? Thanks, Wayne My electrician seems to love looping the hot wire from one switch to another in a 2-gang box. Is this fully against code or just not advisable? I have switches like this, a single hot comes in, and it daisey chained from one switch to another without ever being cut. It is the ONLY time I have found a terminal screw used in my house. Everything else is BACK STABBED. later, tom |
#9
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On Mon, 14 Mar 2005 16:37:42 GMT, blueman wrote:
writes: The NEC is silent on the issue. Basically it is legal On Mon, 14 Mar 2005 02:25:37 GMT, blueman wrote: My electrician seems to love looping the hot wire from one switch to another in a 2-gang box. Is this fully against code or just not advisable? Could someone please explain to me then what is "illegal" about the "looping" that the OP is talking about? Could be a 2002 110.3(b) violation. I just checked the instructions on a box of NM-B and found it says to make connections at the end. With some inspectors(I've heard of), that's is more than enough to fail an inspection hth, tom |
#10
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The Real Tom wrote:
Could be a 2002 110.3(b) violation. I just checked the instructions on a box of NM-B and found it says to make connections at the end. Could you elaborate on what that section covers? Does it deal specifically with NM cable? With conduit installations it's commonplace when running wires from box to box to simply leave a loop in each box and cut off some insulation from the loop and hook it around the screw terminal. |
#11
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On Tue, 15 Mar 2005 01:19:45 GMT, Bob wrote:
The Real Tom wrote: Could be a 2002 110.3(b) violation. I just checked the instructions on a box of NM-B and found it says to make connections at the end. Could you elaborate on what that section covers? Does it deal specifically with NM cable? Any NEC quotes are summaries, please read the code for yourself: No, it's a general instruction: "Installation and Use of Equipment". You need to follow the manufacturer's instruction. If the manufacture says to only connect at the ends of insulated conductors, then you need to do so. With conduit installations it's commonplace when running wires from box to box to simply leave a loop in each box and cut off some insulation from the loop and hook it around the screw terminal. Can't say it's too common. Simple since other people I run into, and how I was taught, you cut, pigtail, and wirenut. If you are using a greenie, then just cut, and wirenut. Now with the free end goes to the ground screw. The knawing of insulation in the middle of the wire run seemed to look lazy/unprofessional, so I'm guessing an inspector can hit you as a 2002 NEC 110.12 violation. Remeber i'm still learning, so I listen to what hapens to other electricians and take note. later, tom |
#12
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In article ,
The Real Tom Tom @ www.WorkAtHomePlans.com wrote: I have switches like this, a single hot comes in, and it daisey chained from one switch to another without ever being cut. It is the ONLY time I have found a terminal screw used in my house. Everything else is BACK STABBED. later, tom Maybe naive question, but does "back stabbed" imply some particular kind of wiring (defect?), and if so, what is that? Thanks, David |
#13
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David Combs wrote:
Maybe naive question, but does "back stabbed" imply some particular kind of wiring (defect?), and if so, what is that? Many residential grade (cheap) wiring devices have holes where a 14 gauge solid wire can be "stabbed" in and a spring clamp will hold it in place. It's a labor saving feature that can result in intermittent connections. |
#14
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#15
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On Wed, 13 Apr 2005 03:23:47 GMT, Bob wrote:
David Combs wrote: Maybe naive question, but does "back stabbed" imply some particular kind of wiring (defect?), and if so, what is that? Many residential grade (cheap) wiring devices have holes where a 14 gauge solid wire can be "stabbed" in and a spring clamp will hold it in place. It's a labor saving feature that can result in intermittent connections. technical term for arcing and flickering of lights, applances, etc.... thx, tom |
#16
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According to The Real Tom tom @ www.Love-Calculators.com:
"back stabbing" is what I call when you strip the wire and push through the tiny holes in the back of a device(switch, receptacle, etc) that only uses spring pressure to hold onto the wire. So all you do is stab it into the hole. Scary things those. This is different from what I call 'back wiring' where you insert the wire into the back, under a pressure plate and tighten a screw. Backwiring was described to me as the act of bending the ground wire back over the cable sheath, and using the box clamp to "make the ground" connection. Ick. -- Chris Lewis, Una confibula non set est It's not just anyone who gets a Starship Cruiser class named after them. |
#17
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Back stab connections are legal. However the perspective is
human safety. Code is only concerned with human safety. You have other concerns beyond human safety. Concerned not addressed by code. Intermittents created by back stab connections do not adversely affect lights. But they can be catastrophic to computer data. Notice the difference. Back stabbing is just fine from the perspective of human safety. But a disaster for data safety. Perspective. David Combs wrote: In article , The Real Tom Tom @ www.WorkAtHomePlans.com wrote: I have switches like this, a single hot comes in, and it daisey chained from one switch to another without ever being cut. It is the ONLY time I have found a terminal screw used in my house. Everything else is BACK STABBED. Maybe naive question, but does "back stabbed" imply some particular kind of wiring (defect?), and if so, what is that? |
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