9 replies to this topic

[ski89]

shouldn't the bonding wire be bigger?

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[okemopoma]

ski89, on Dec 10 2006, 07:30 PM, said:

shouldn't the bonding wire be bigger?

Maybe. If this is just a Equipment Grounding Conductor (bonding wire), and not a Grounding Electrode Conductor (wire that is the path to earth), then it is not required to be larger than the biggest current carrying conductor. However, it must be sized from Table 250.122 of the NEC. The size of the EGC depends on the size of your Overcurrent Device. Ex. 400A would need #3 copper min. 200A needs #6, 100A needs #8, 30-60A #10.

Different story if this is the GEC, then Table 250.66 comes into play. Now, you go by wire size, not OCPD size. Ex. #1-1/0 gets #6 copper, 3/0-350kcmil gets #2 copper.

Remember, all these are minimums. Bigger is safer. In my opinion, you cant be bonded or grounded enough.

[spark's]

Okemo is right... I'll add... I can see by the pic u have IMC (intermediate metal conduit) as your raceway... If it is (and probably is) a straight run back to the panel... If not this does not apply, ART. 342.60 say's IMC shall be permitted as a equipment grounding conductor... This also applies to RMC.. If the panel is in the same room as the disconnect or junction box i would,nt worry to much... If the panel is 200 ft away and the run is buried.. I would not use either pipe as a bond back to the panel... To many chance's for the pipe to break or get crushed and go unnoticed, breaking your ground... Pipe is sized by conductor or conductor's, size, and the number of conductor's that are in the race... To many variable's to list... Hope that help's... If you can get a pic of the whole shabang that would be great...

[ski89]

nope conduits are plastic

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[spark's]

GIMME A SEC LOL...

[ski89]

OCPD to this device is 70A, therefore I need a #8 if it is an EGC. If it is a GEC and my conductors are #6 I need a ?. If it is required to be larger than the biggest current carrying conductor it should be a number 4? If bigger is better and the previous installation had large grounding or bonding wires then I believe I need something bigger than what's in there now.

This is the previous installation.

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[spark's]

Well the fact now that it is PVC and not IMC (the plastic bushing on the plastic pipe threw me off) put's us right back to the size of the feeder's... I'm not sure of the AWG of the feeder's but they look bigger than 4#... 4# copper is the differance of 100 amp's or not sooo... let's say the wire in the pic's are atleast that size or bigger.. The bonding wire's in the pic is let's say the same size as the grounding wire's in those open box's above (recep's) no bigger than we'll say 12#... On a 100 amp feed you would need a 8# copper which is 5.486 circular mil's...and a 10# which is 4.166 and a 12# is 3.302 cmil's time's 2.... Would cover your base if they both go both go back to the panel,,, Do they both go back to the panel??? If they dont or do add up then.... yes there is or is'nt enough copper to cover the amp's....

[spark's]

If your conductor's are 2# or smaller u need a 8# awg wire for a GEC no less no more... back to circular mil's... and are they both going back to the panel??? If so you could put a drill on the end of both wire's and twist them together for a better apperience... Also wire size varie's on type and what the caseing is rated for....

[ski89]

I found some #4 that I am going to work in.

[spark's]

This is a bonding wire that we're talking about and a 8# wire will work just fine... If you found some 4# even better it's good up to 300 amp's......