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service bonding 2011 NEC

B

BSSTG

Gold Member
Joined
Nov 30, 2009
Messages
729
Location
Seadrift, Tx.
Greetings all,

Well I'm confused with 250.92 (B).

My question is this. Are grounding bushings or grounding locknuts required on service conduits under all circumstances in lieu of standard locknuts now? Or are the gounding bushings and locknuts only required around concentric knockouts, reducing washers and so forth? It looks to me as if standard locknuts are not allowed for bonding of service equipment under any circumstance but I'm not sure if I'm reading this right

thanks

BS
 
Here's how I understand it.

All the stuff in section 250.92(A)(1)&(2) are required to be bonded together. The method for bonding these items together can be any of the (4) methods indicated in section 250.92(B). Standard locknuts or bushings used by themselves can not be used to satisfy these requirements. In addition, bonding jumpers are required where the potential for an impaired connection is present due to inadequate connection beetwen an enclosure and a raceay fitting.

The moral of the story is this. When in doubt, bond.
 
BSSTG said:
Greetings all,Well I'm confused with 250.92 (B).

My question is this. Are grounding bushings or grounding locknuts required on service conduits under all circumstances in lieu of standard locknuts now? Or are the gounding bushings and locknuts only required around concentric knockouts, reducing washers and so forth? It looks to me as if standard locknuts are not allowed for bonding of service equipment under any circumstance but I'm not sure if I'm reading this right

thanks

BS
Click to expand...
This change was just a re-wording of the requirements already contained in 250.92.

Standard locknut can't be used for bonding on the line side of the service and bonding bushings or locknuts are required to bond metallic raceways on the line side of the service even if concentric, eccentric or reducing washers are encountered.

Chris
 
Also, if we could have the section.. for those of use who don't have the 2011 NEC yet :) thanks!
 
Francis: Good enough! This is a section often missed. Sometimes a picture goes along ways to allowing ones understanding od an issue. It also can stimilate more discussion on a subject that needs clear understanding.
 
TimNY said:
Also, if we could have the section.. for those of use who don't have the 2011 NEC yet :) thanks!
Click to expand...
This is how it reads.

250.92 Services.(B) Method of Bonding at the Service. Bonding jumpers

meeting the requirements of this article shall be used

around impaired connections, such as reducing washers or

oversized, concentric, or eccentric knockouts. Standard

locknuts or bushings shall not be the only means for the bonding

required by this section but shall be permitted to be installed

to make a mechanical connection of the raceway(s).

Electrical continuity at service equipment, service raceways,

and service conductor enclosures shall be ensured by

one of the following methods:

(1) Bonding equipment to the grounded service conductor

in a manner provided in 250.8

(2) Connections utilizing threaded couplings or threaded

hubs on enclosures if made up wrenchtight

(3) Threadless couplings and connectors if made up tight

for metal raceways and metal-clad cables

(4) Other listed devices, such as bonding-type locknuts, bushings,

or bushings with bonding jumpers
Click to expand...
 
So here is the question. If the service disconnect is a regular panelboard and the metal raceway entering the service panel comes through a concentric knockout, needs to be bonded with a bond bushing or bonding locknut, does that mean that all branch circuits and feeders that leave that same service panelboard must have the same bond bushings or bonding locknut if they are connected to a concentric KO with metal raceway?
Food for thought..... :)
 
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