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bob22 04-03-2010 09:00 AM

What wire gauge for plumbing ground?
I need to install a grounding jumper wire around a pressure reducing valve in my all copper plumbing system. My question is what gauge copper to use? I've a 200 amp service but don't go anywhere near that load.
I saw this on a website and wonder if I need the size shown for 200 amp service for this jumper (#3). I was going to go with #6 or 4. Not sure if #3 would fit into 3/4" grounding clamp? The original house panel was 100 amp but it was just upgraded and inspected with no changes to original grounding to outside or other plumbing jumpers (gas pipe to water):
Table of Electrical Ground Wire Sizes

Ground Wire Gauge CU (Copper) - wire size Electrical Service Size
#8 to 100A
#6 to 125A
#4 to 165A
#3 to 200A
Some other threads (one or two on this site) say #4 copper is good for up to 200 amp service.
I guess #4?


brric 04-03-2010 09:14 AM

I would use # 4.

# 3 is larger and would work as well.

Speedy Petey 04-03-2010 03:57 PM

#4cu for the typical 200A service.

Where did you find that inaccurate chart?
What you are looking for can be found in NEC T250.66

bob22 04-04-2010 07:39 PM

The chart came from:
THanks for the info. I used #4.

frenchelectrican 04-04-2010 08:01 PM

You can use 25mm˛ { #4 AWG } conductor for 200 amp service that is the bonding conductor so that is legit for it.


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