Question on GEC size

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Mike Lang

Mike Lang

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New Jersey
I'm studying for my NJ license and I know how to size my GEC with Table 250.66. OK now in 250.66 A it says that when conecting to a rod, pipe, or plate electrode that the sole connection portion of the conductor doesn't have to be larger than #6 copper or #4 alum.

I don't understand... can someone please explain this to me?

does this mean that at that point of connection to the GEC we can butt splice down to a # 6 ???

thanks
 
Mike Lang said:
I'm studying for my NJ license and I know how to size my GEC with Table 250.66. OK now in 250.66 A it says that when conecting to a rod, pipe, or plate electrode that the sole connection portion of the conductor doesn't have to be larger than #6 copper or #4 alum.

I don't understand... can someone please explain this to me?

does this mean that at that point of connection to the GEC we can butt splice down to a # 6 ???
Click to expand...
No, it means that the conductor attached only to the made electrode need not be larger than those sizes, even if it attaches to another part of the electrode system.

The rest of the electrode bonding conductors must be sized according to 250.66. In other words, if you daisy-chain the bonding with jumpers, if you make the made electrodes the last link, that last jumper can be smaller.
 
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Mike Lang said:
I'm studying for my NJ license and I know how to size my GEC with Table 250.66. OK now in 250.66 A it says that when conecting to a rod, pipe, or plate electrode that the sole connection portion of the conductor doesn't have to be larger than #6 copper or #4 alum.

I don't understand... can someone please explain this to me?

does this mean that at that point of connection to the GEC we can butt splice down to a # 6 ???

thanks
Click to expand...

Mike the wire to the rod does not have to attach directly to the wires to the water pipes, etc. It can be a different wire. Around here we take a #6 from the meter base to the rod and from the panel a #4 (200 amps) to the water pipes.

Some areas will not let you attach the rod GEC in the meter so you would come out of the panel with that also.
 
LarryFine said:
No, it means that the conductor attached only to the made electrode need not be larger than those sizes, even if it attaches to another part of the electrode system.

The rest of the electrode bonding conductors must be sized according to 250.66. In other words, if you daisy-chain the bonding with jumpers, if you make the made electrodes the last link, that last jumper can be smaller.
Click to expand...

Oh I see now... The first GEC from the main panel must be sized to Table 250.66 then if i jump off that electrode to another that wire can then be smaller or no larger than #6 copper.

Right

I've always ran 2 wires because it's usually easier for me due to location of the ground rods and the water pipe.
 
Take a look at this graphic:

1100202225_2.jpg


The GEC going to the water pipe is sized according to 250.66. The other conductors are bonding jumpers. The bonding jumper to the concrete encased electrode is not require to be larger than #4. the bonding jumper to the rod is not required to be larger than #6, etc.
 
infinity said:
The GEC going to the water pipe is sized according to 250.66. The other conductors are bonding jumpers. The bonding jumper to the concrete encased electrode is not require to be larger than #4. the bonding jumper to the rod is not required to be larger than #6, etc.
Click to expand...
Right. The idea is that all pathways from neutral/EGC bond to electrode to electrode must be full sized - except when the made (rod, plate, etc.) electrode is the only thing relying on that path.

The reasoning is that a #6 copper is capable of conducting all the current that the made electrode is, so there's no reason for that to ever be of greater ampacity.
 
I hope I finally understand this

I hope I finally understand this

Fantastic Thread!
Im sure its been said and done many times, but it answered all my questions at hand........er......I think.
Just to clarify........The GEC to the underground copper water system (cold water bond, where available)would be sized according to 250.66? Is that because the underground metalic piping has a low enough resistance to potentially carry full fault current?
Thanks to all you guys that make this forum a success!
 
POWER_PIG said:
Fantastic Thread!
........The GEC to the underground copper water system (cold water bond, where available)would be sized according to 250.66? Is that because the underground metalic piping has a low enough resistance to potentially carry full fault current?
QUOTE]

PP, Fault current will seek the source neutral ( grounded conductor ) in order

to provide enough current to trip the OCPD. The GEC is mostly for lightning,

line surges, unintentional contact with high voltage lines, and to stabilize the

voltage to earth during normal operation.
Click to expand...
 
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