ECN Forum Forums Code Related Discussion NEC & other Code issues bond bushings

gserve...the code states in 250.92(B)(4)...

"Standard locknuts or bushings shall not be the sole means for bonding required by this section"

Yes, another approved device, such as a bonding-type locknut or a bushing with a bonding jumper must be used.

e57 has a good point on that offset nipple made of diecast material, if it is. Better use a steel offset nipple which is probably UL approved for enclosing service entrance conductors.

shortcircuit

Hi,
Almost ALL hubs are the VERY same material as the offset nipple your talking about.

I do not know how many of these I have replaced due to cracks and breaks...that said I have NEVER seen a BROKEN offset nipple in my 27 years in the trade.

Can you PROVE that a die cast hub is four times or more stronger than another die cast part? Please do if you can, I have NEVER heard anything like that!

There may be steel hubs out there but that is a special order item not a standard issue.

I also beleive there are se offset nipples available for making that little offset you need to get over to the wall or to straighten the pipe. Most hubs will provide some movement for aligning..I use them all the time and have NEVER had a single problem.

there is no difference in using a die cast part on a service vs a die cast straight connector on emt that feeds anything else of that nature...xfmr, disco etc.

So do we now stop using die cast connectors and parts? NO!

which is stronger die cat or PVC? do we stop using pvc too?

if you want a rigid offset nipple because you are concerned then look at these:
http://www.cornerhardware.com/cat_1597/

look at this page/s
http://www.selfhelpandmore.com/homewiringusa/2002/maindwelling/overtemp/overtempshow.htm


there is nothing wrong woth using a die cast offset with a service entrance raceway...

-reagrds

greg




[This message has been edited by mustangelectric (edited 03-17-2005).]

I would accept a Meyer's Hub as I would not call any lock on these, I have seen, 'standard'. They are usually beefier with a lot more teeth.

As far as concentric ko's, the code is not explicit. It says where formed to impair the path to ground. What exactly that means can be debated forever.

I would say the arrangement you have described meets bonding requirements, but may not meet 250.6(a) (99 NEC)if the grounded conductor is bonded to the metersocket enclosure.

I guess it all depends on whether you believe the standard lock nut connection on the meter side is effective. If yes, then 250.6(a) is violated. If not, then it is compliant.

I'd say yes... either a bonding locknut or bushing.

It seems like 250-72 (e)of the '96 Code says as long as you use a bonding locknut or bushing at your penetration of the largest/specific size KO, you don't require an additional jumper like you do around concentrics, but it still requires a "bonding type locknut or bushing"

250-72 (d)(1996) requires bonding jumpers around concentric / eccentric KO's, most likely due to concerns about the partial punch-through of the metal for each size impeding the flow of objectionable current to ground.

If you're using the largest size, then the concerns over path to ground for the area of the penetration of the box aren't applicable. Same argument for size-specific punched openings.


[This message has been edited by DougW (edited 03-20-2005).]