Insulated EGC

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JohnJ0906

JohnJ0906

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I was curious about the requirement in 680.25(B), that the EGC for a swimming pool feeder be insulated. Does anyone know why the insulation is a requirement? I looked at the NEC Handbook, but it really didn't give any insight as to the reasoning.

Thanks
 
The EGC is intended to provide a low-impedance ground-fault current path to the source (which would assist in clearing a ground fault).
The insulated EGC is intended to just clear fault current and a bare conductor might impede that purpose? Just a thought but the logic seems sound

JJ
 
I think the reason for the insulated EGC is to insure that it is a wire and not, for example

a pipe. This is just a guess on my part.
 
Equipotential Bonding Grid. The parts specified in 680.26(B), of 2005 NEC, shall be connected to an equipotential
bonding grid with a solid copper conductor, INSULATED, covered, or bare, not smaller than 8 AWG or rigid
metal conduit of brass or other identified corrosion-resistant metal conduit.


JJ
 
Benaround "I think the reason for the insulated EGC is to insure that it is a wire and not, for example

a pipe. This is just a guess on my part."

Interesting thought



JJ
 
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Well the NEC is not a theory book, so it does not justify the requirements.

With that said I have a different thought on why an insulated EGC is required; to minimize the likelihood of stray voltage from external current. For example if some metallic raceway were used with a bare EGC, it is possible for stray currents to be induced on the EGC therefore creating a voltage potential along the length.
 
dereckbc said:
With that said I have a different thought on why an insulated EGC is required; to minimize the likelihood of stray voltage from external current. For example if some metallic raceway were used with a bare EGC, it is possible for stray currents to be induced on the EGC therefore creating a voltage potential along the length.
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I was thinking this might be the reason, but I was thinking that someone here might know for sure.
 
I had heard that it was an attempt to minimize the effect of possible corrosive elements on the EGC from the pool equipment and environment. I'm not sure about reason for the requirement either.

Follow-up question: If we don't know the basis for the requirement, would that tend to make it a less offensive code to violate, or does it matter to you? Would you defend it tooth and nail for "code is code" 's sake? :)
 
What Dereck has posted is what I have been taught as well. The conductor may start in a panel in a house and not even be near corrosive conditions.

But there is a chance for some type of incidental contact along it's path that insulation may help to protect against.
 
George Stolz said:
Follow-up question: If we don't know the basis for the requirement, would that tend to make it a less offensive code to violate, or does it matter to you? Would you defend it tooth and nail for "code is code" 's sake? :)
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Although I like to understand the reasoning behind a code requirement, I would like to think there is a sound reason behind it even if I don't understand. I'm not going to knowingly violate a code requirement just because I don't know the reason behind it.

However, knowing the reason DOES make it easier to defend/ explain certain requirements. :smile:
 
Insulation around a conductor will not impact its ability to carry fault current. Nor would it impact the ability for external magnetic fields to induce a voltage on the conductor. The only reason that makes sense to me is to protect the metal conductor from corrosion. The probability of there being a corrosive environment is slightly higher in a pool or hot tub environment than it would be for, let us say, a normal bathtub. That is because of the chemicals used to keep undesired living organisms from setting up housekeeping in and around the water.

A secondary reason comes to my mind as well. We go through extra trouble with regard to the EGC in a patient care area. We also go though extra trouble for pools. What do these two areas have in common? The likelyhood of a person coming into contact with something electrical. So perhaps it is just worth a little extra trouble.
 
charlie b said:
Insulation around a conductor will not impact its ability to carry fault current. Nor would it impact the ability for external magnetic fields to induce a voltage on the conductor. The only reason that makes sense to me is to protect the metal conductor from corrosion. The probability of there being a corrosive environment is slightly higher in a pool or hot tub environment than it would be for, let us say, a normal bathtub. That is because of the chemicals used to keep undesired living organisms from setting up housekeeping in and around the water.

A secondary reason comes to my mind as well. We go through extra trouble with regard to the EGC in a patient care area. We also go though extra trouble for pools. What do these two areas have in common? The likelyhood of a person coming into contact with something electrical. So perhaps it is just worth a little extra trouble.
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All of this makes sense until you realize that the wire will be bare at it's most vulnerable points-- the terminations. So....
 
I went looking for some sort of answer to the reason in the ROPs for 2008, 2005 and 2002. I found nothing that directly addressed the insulated RGC requirement.

I did find at least two, maybe three instances where the CMP for Article 680 turned done proposals due to corrosion issues.

I think Charlie is onto something. :smile:

All of this makes sense until you realize that the wire will be bare at it's most vulnerable points-- the terminations. So....
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I say they do what they can, they could have us use 'potting compound' at the connections ............. oh wait, they already do for some places. :smile:
 
charlie b said:
Insulation around a conductor will not impact its ability to carry fault current. Nor would it impact the ability for external magnetic fields to induce a voltage on the conductor. The only reason that makes sense to me is to protect the metal conductor from corrosion. The probability of there being a corrosive environment is slightly higher in a pool or hot tub environment than it would be for, let us say, a normal bathtub. That is because of the chemicals used to keep undesired living organisms from setting up housekeeping in and around the water.

A secondary reason comes to my mind as well. We go through extra trouble with regard to the EGC in a patient care area. We also go though extra trouble for pools. What do these two areas have in common? The likelyhood of a person coming into contact with something electrical. So perhaps it is just worth a little extra trouble.
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Interesting thought. Presuming THWN was used...is it rated for Chemical corrosion? I didn?t research anything that specified that. Your logic seems sound but is the insulation listed for chemical corrosion.

JJ
 
JJWalecka said:
Interesting thought. Presuming THWN was used...is it rated for Chemical corrosion? I didn?t research anything that specified that. Your logic seems sound but is the insulation listed for chemical corrosion.

JJ
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It keeps the mostly water corrosive liquid from getting to the copper. Many chemicals that are corrosive to metals have little or no effect on the commonly used insulations.
 
i dont think its a chemical issue. it has to do with the fault not being reduced by trying every path back by being uninsulated but direct back to pnl
thats my story and im sticking to it....:)
 
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