Objectionable current

[silverromex]

I have been red tagged before when I forgot to run a bonding jumper from the meter base enclosure to the service panel. For a 200A residential panel this was done with a #6 copper wire. I recently read where doing so could be a hazard because by the neutral and grounding conductor now being in parallel with each other the unbalanced current flows through both conductors. If the grounded conductor loses its continuity then the grounding conductor would then carry all of the unbalanced (neutral) current. A hazard would then exist if the grounding conductors ampacity is less than the amount of current flowing through it. So why is bonding the two enclosures together a code requirement if doing so creates a possible hazard? Thanks.

 

[electricman2]

Re: Objectionable current

I have been red tagged before when I forgot to run a bonding jumper from the meter base enclosure to the service panel.

What article was cited to require this?
It is true that the enclosures must be bonded together, however this is accomplished by bonding both to the grounded service conductor.

 

[silverromex]

Re: Objectionable current

Originally posted by electricman2:
What article was cited to require this?

250.4(A)(3),By having the grounded conductor and the grounding conductor bonded together in meter base and in the service panel, like the inspector wanted it done, creates a parallel path for the neutral current. I dont understand the logic behind bonding the 2 in the meter base.

[ August 27, 2004, 09:04 PM: Message edited by: silverromex ]

 

[electricman2]

Re: Objectionable current

The intent of 250.4(A)(4) is met when the meter enclosure is bonded to the grounded service conductor and when the main bonding jumper required by 250.28 is installed. There is no need for a separate bonding jumper between the two enclosures. As you pointed out this is a parallel path.

 

[jap2525]

Re: Objectionable current

there is no way to avoid a parallel path from the disconnect to the meter if the connection nipple between them is a rigid nipple.the best way to avoid this from most replies was to install a pvc nipple between the meter and the service disconnect,,,,this makes sense,,,,but then there was a post where the inspector had him remove the pvc nipple between the meter base and the service disconnect and install a rigid nipple and bond it at both ends.regardless of wether a rigid nipple is bonded at both ends it is still a parallel path!a bonding wire is not required between the meter and the disconnect,but what difference would it make if it was in there or not? a parallel path was already created when the neutral was bonded to the can and a rigid nipple used.Are we saying (1) parallel path is ok but (2) parallel paths are not?it doesnt make sense.
the best thing for them to do is make it a code violation to install a conductive nipple between the meter and the service disconnect.

 

[silverromex]

Re: Objectionable current

Why not bond the grounding and grounded conductor in the meter base and eliminate the bonding of the 2 in the service disconnect, wouldn't this would eliminate the parallel paths?

[ August 28, 2004, 10:48 AM: Message edited by: silverromex ]

 

[iwire]

Re: Objectionable current

Originally posted by silverromex:
Why not bond the grounding and grounded conductor in the meter base and eliminate the bonding of the 2 in the service disconnect, wouldn't this would eliminate the parallel paths?

 

[jap2525]

Re: Objectionable current

no matter how much we talk about this there never seems to be a definite answer.What we need is someone of authority to define the intent of these code requirements.It seems different people install services differently and have a valid stance for thier installation.They end up changing thier installation just to satisfy the inspector to get the power turned on,but then leave the job trying to accept the judgement of the inspector even though they cannot find a good reason to.When someone asks a question similar to what one has already encountered they defend the inspectors decision that made them change it whether or not it made sense to them at all.Who can we go to to get a definite answer to these questions.