Is a bond bushing required by code to be installed on an offset nipple where one end is screwed into a myers hub mounted on the main disconnect enclosure and the other end installed into the bottom of a meter socket? These are service entrance conductors from the bottom of the meter to the top of the main disconnect(line side). Code reference please. Thanks

Hi,
Only if it is a concentric knockout..article 250 something..i will see if i can dig it up..

ok 250.92 (B)..the offset nipple is irrelevant..it doesnt matter what the raceway is ..if it is METALLIC...EXCEPT PVC of course.

That is because when the larger knockouts break the continuity is lost..

I re-read your post...you do not need a bonding bushing at the disco only the meterbase.

regards

greg



[This message has been edited by mustangelectric (edited 03-16-2005).]

Inspectors in my area do not feel that a Meyers hub meets the requirements of
250.92(B)(1) thru (4), because of the neoprene gasket, and would require a bonding bushing in the case you describe. Meyers hubs with bonding means are available.

Hi,
Myers hubs are desinged to BITE into the surface or the encloisure..the gasket is insterted in groove and does not impair the bearing of the locknut, it only keeps out water, dust etc.

As mentioned you can get myers hubs with a ground screw on the locknut..

I dont see why an inspector would not allow a meyers hub as a means of grounding!

In my opinion there is NO BETTER HUB! There are only 10 billion or more of them in use!

I have put hundreds of them in nuclear plants, refineries and oil fields with and without grounding busings...

if a 1/2 locknut is good enough there is twice the material getting a bite with a meyers hub.

Very funny though!

-regards

greg

Not all Myers Hubs are the same... http://www.electrician.com/articles/myers.htm
http://www.crouse-hinds.com/crousehinds/pdf/CH62318C-0077.pdf

steve

If all the concentric knockouts are removed to the largest size then is it still required to have a bond bushing?

Hi,
Well what do you know!

Never heard of this before now.

I guess there will be a lot of retrofitting if there is a recall!

From now on I guess be sure to use the ones with the ground screw!

Not so funny after all!

-regards

greg

Hi,
I would say NO to that but better check it with the man..he is the one with the green sticker!

I dont see why it would be then considered concentric.

-regards

greg

I have had discussion with inspectors in my area and they feel that standard Myers hubs are acceptable. I haven’t spent much time looking through the UL directors but did look up the UL file number (E-27258) for the Basic hubs in Steve’s link. There is a note at the bottom of the UL page that says “suitable for use with service entrance conduit”.

Curt

Speaking of “suitable for use with service entrance conduit”. Is an off-set nipple “suitable for use with service entrance conduit”? NEC doesn't seem to touch on it in 230.43, but does UL list these thin die cast parts as “suitable for use with service entrance conduit”? I wouldn't use them as I don't think they have the physical strength to protect service conductors. As far as die cast parts go, a bolt on hub is made a lot stronger, like four or more times as strong as an off-set nipple. The area I work in will only accept IMC or RMC. And, I have never seen an off-set nipple used for any part of a service, other than on this forum a while back.

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).]