Burned up Bond

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Dexie123

Senior Member
I recently took a pull box cover off and saw the following. Here there were some galvanized deck pipes going into a pull box but are not entered into the box via a KO. So the installers used a bonding #6 from pipe to pipe and then to the box.

I had been told by someone that one of the breakers that feed the wired that are in these pipes (think they're 350's) had a dead short but the breaker blew only after like 30 seconds or so (Unsure of the time but it was long). Then I ran into the burned up bond.

Is the #6 too small? Should it be determined by article number 250.66 or 250.122? Or some other sections.

Thanks

http://www.turboimagehost.com/p/7674550/Bond.png.html
http://www.turboimagehost.com/p/7674551/Burned_Bond.png.html
 

iwire

Moderator
Staff member
Location
Massachusetts
Should it be determined by article number 250.66 or 250.122?

When there is a breaker or fuse ahead of it like with a feeder or branch circuit you use 250.122.

If there is no breaker or fuse ahead of it like services and transformer secondary conductors you use 250.66

If the circuit conductors are 350s it is likely that a 6 AWG jumper is too small.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
If you are bonding on the load side of an overcurrent device, 250.122 would be your guide and #6 would be too small for a 350 amp OCP.
 
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