250.148

[jxofaltrds]

Most of the local inspectors require all the equipment grounding conductors (EGCs) in a box to be connected regardless of their wire size or ?association.? For example, consider a two-gang box in a kitchen with a small appliance branch circuit and a lighting circuit. Some say it is because of ?equipotential? issues. However, the heading of this section in part references the ?Continuity ... of Equipment Grounding Conductors.? In the body of this section, it states, ?any EGC(s) associated with those circuit conductors shall be connected.? How are these two circuits associated? If the inspectors are correct, why does the NEC not state, ?all EGCs in the box shall be connected together??
?
I was taught this way but after discussing this at last nights IAEI meeting I am questioning if we are required to tie EGC of different branch circuits together, specially in a NM box.

Thoughts?

http://www.ecmag.com/section/codes-standards/outside-feeders-egcs-and-more

250.148 Continuity and Attachment of Equipment
Grounding Conductors to Boxes. Where circuit conductors
are spliced within a box, or terminated on equipment
within or supported by a box, any equipment grounding conductor(
s) associated with those circuit conductors shall be connected
within the box or to the box with devices suitable for
the use in accordance with 250.148(A) through (E).

 

[iwire]

With a metal box it is a moot point, all will end up joined one way or another.


However with a plastic box I do believe the NEC allows us to keep each circuits EGC separate from each other. George Stolz taught me this.

To me keeping them separate is just dumb to do and if a metal plate is used it will be the metal plate bonding the the separate EGCs together. During a ground fault this could cause the plate to carry fault current between devices.

 

[mjf]

Most of the local inspectors require all the equipment grounding conductors (EGCs) in a box to be connected regardless of their wire size or ?association.? For example, consider a two-gang box in a kitchen with a small appliance branch circuit and a lighting circuit. Some say it is because of ?equipotential? issues. However, the heading of this section in part references the ?Continuity ... of Equipment Grounding Conductors.? In the body of this section, it states, ?any EGC(s) associated with those circuit conductors shall be connected.? How are these two circuits associated? If the inspectors are correct, why does the NEC not state, ?all EGCs in the box shall be connected together??
?
I was taught this way but after discussing this at last nights IAEI meeting I am questioning if we are required to tie EGC of different branch circuits together, specially in a NM box.

Thoughts?

http://www.ecmag.com/section/codes-standards/outside-feeders-egcs-and-more

250.148 Continuity and Attachment of Equipment
Grounding Conductors to Boxes. Where circuit conductors
are spliced within a box, or terminated on equipment
within or supported by a box, any equipment grounding conductor(
s) associated with those circuit conductors shall be connected
within the box or to the box with devices suitable for
the use in accordance with 250.148(A) through (E).

I guess the NEC needs to add another definition: associated.

One COULD surmise that as soon as the wiring from any two branch circuits enter the same box they become associated.

 

[iwire]

One COULD surmise that as soon as the wiring from any two branch circuits enter the same box they become associated.

In the same building?

Supplied by the same power company transformer?

In the same state?

 

[Ponchik]

I always keep #12 and 14 EGC separate. I do not see any issue with it.

In a double device box with a metal plate it is bonded via the device and the largest (usually #12 in my case)

 

[iwire]

I always keep #12 and 14 EGC separate. I do not see any issue with it.

In my opinion that is less safe. I am not saying it is unsafe, just saying that connecting all EGCs together in each location is safer and will keep things closer to equilpotential during a ground fault. It lowers the impedance of the grounding system.

In a double device box with a metal plate it is bonded via the device and the largest (usually #12 in my case)

I find the idea of plate bonding the EGCs together less than ideal.

During a ground fault there is significant voltage drop on the effected EGC, this could cause arcing at the plate screws until the breaker trips.

I don't see it as a huge deal, just something I chose to avoid by bonding all EGCs together at every opportunity.

 

[electricalist]

I have supervisors who pull a ground wire in every conduit. Im the lucky guy who gets go find a ground bar get my tap driver and my wire brush wheel and a nut and bolt and lockwasher. Every time I say seriously , again , me. He says everytime. It has to be done. Lol. As for egc in houses it seems when there a multi gang switch box with multiple circuits we kept I think we kept them seperated because it was believed that 1 ground was rated for that size of fault 1 120 v not 2 . .I could be mistaken. I personally dont like tieing every ground I come across together. Just seems wrong. Id think if it was the same do or dont then we could ground every panel in a bldg to bldg steel at the panel and it would be good.

 

[ActionDave]

.... Id think if it was the same do or dont then we could ground every panel in a bldg to bldg steel at the panel and it would be good.

If everything is done to code every panel in the building will have an EGC and a GEC connection to the building steel.

 

[electricalist]

If everything is done to code every panel in the building will have an EGC and a GEC connection to the building steel.

Your right. I think what I mean to say and how I say it cause confusion more than make sense.

 

[mjc763]

I usually connect them all together.

 

[George Stolz]

However with a plastic box I do believe the NEC allows us to keep each circuits EGC separate from each other. George Stolz taught me this.

That's pretty funny - enough time has elapsed since that conversation that my natural habit of tying all EGCs together had settled into my head as code, and reading the article (and then this thread) was breaking my head out of it's rut, and as this was coming to pass I read this. :lol:

About the most tiring type of learning is learning you already learned that.

 

[George Stolz]

Id think if it was the same do or dont then we could ground every panel in a bldg to bldg steel at the panel and it would be good.

To omit the equipment grounding conductor in feeders because all panels are tied to building steel would increase the impedance of that path enough that the breakers may never trip. 300.3(B) requires all conductors in the same raceway or cable for a reason, and it's not tidyness.

 

[infinity]

I've mentioned this before but does the NEC really want use to connect all of the EGC's together, even in a large feeder pull box that may have multiple sets of say 20-#3/0 EGC's?

 

[iwire]

I've mentioned this before but does the NEC really want use to connect all of the EGC's together, even in a large feeder pull box that may have multiple sets of say 20-#3/0 EGC's?

Might as well directly connect them as it is going to happen anyway in a metal pull box.

Consider that in a steel frame / studded building pretty much every EGC is connected together.