100 amp service

[peter d]

Based on T250.66, my GEC only needs to be #8 CU max based on #2 AL service conductors (very common in my area). Now let's say the ground rods are the only electrodes that I use.

Does that mean I only need to run #8 to them?

Or must I still use #6 to the ground rods based on 250.66(A)? It says "shall not required to be larger than #6 CU" which suggests that #8 is fine since it's the maximum size required by T250.66.

My gut instinct tells me the #8 is fine, but this has always confused me nonetheless.

{I'm purposefully not mentioning the rebar bonding because I don't have my '05 with me.}

 

[boboelectric]

Re: 100 amp service

poco where i live require #6 min

 

[buck33k]

Re: 100 amp service

#8 cu to the rods would be fine based on your information and table 250.66. The GEC would not be required to be larger than #6 cu as the sole connection to the rods in any case.

 

[electricmanscott]

Re: 100 amp service

I'd say #8 is all that you need since it says that it is not required to larger than #6. Does not say it can't be smaller.

 

[sheldon_ace]

Re: 100 amp service

I would check with your local poco. They might have their own requirements. In my neck of the woods, all residential services require a #4 bare copper minimum on any size service. They don't size the GEC according to size of service entrance. So if you install a 400A service, all that is required is #4.

 

[pierre]

Re: 100 amp service

I do not see or understand why the local jurisdiction would require larger than an 8 AWG GEC for a 100 ampere rated service???

It shows me they do not understand the dynamics of grounding!!!

If they are so concerned about the grounding issue, why don't they make it a new requirement to enclose the foundation in a copper shield?

 

[don_resqcapt19]

Re: 100 amp service

Pierre,
A lot of the utilities require a minimum of #6 or #4 because of the rule in 250.64(B).
Don

 

[pierre]

Re: 100 amp service

Okay Don, I understand that the NEC requires the protection for that size conductor, so lets say that we provide protection.... will those utilities then permit the installation of 8 AWGG

But aside from the protection, do you agree that the "grounding" to ground rods is a waste of material and the time it takes?

 

[boboelectric]

Re: 100 amp service

BIGGER IS BETTER!

BOB 84,PA.

 

[boboelectric]

Re: 100 amp service

I a'm on the side of the believers that GROUND RODS only serve as lighting protection. Why compromise SAFETY?

BOB,84,PA.

 

[don_resqcapt19]

Re: 100 amp service

Pierre,
No, the utilities do not permit the use a smaller code compliant GEC if protection is supplied. Remember that many times the utility primary neutral is undersized, and the earth is used as part of their return path. The primary and secondary neutrals are bonded together at the utility transformer.

As far as the need for a ground rod, its most important function is lightning protection, and protection from accidental contact with higher voltage systems.
Don

 

[peter d]

Re: 100 amp service

Originally posted by boboelectric:
BIGGER IS BETTER!

Why?

[ October 29, 2005, 07:37 PM: Message edited by: peter d ]

 

[peter d]

Re: 100 amp service

Originally posted by don_resqcapt19:

No, the utilities do not permit the use a smaller code compliant GEC if protection is supplied. Remember that many times the utility primary neutral is undersized, and the earth is used as part of their return path. The primary and secondary neutrals are bonded together at the utility transformer.

In my area, the poco's are not concerned with the GEC unless it is a customer built transformer pad, in which case they have a strict set of specs that must be followed. In any case, around here, the AHJ is responsible for signing off on an installation, and then the AHJ gives the green light to the poco to energize the installation. So a #8 GEC would be fine with protection because it meets the NEC.