Potential for GEC to carry load if the grounded service conductor 'goes bad'

[Kaybeeoh84]

I am wondering if running a separate wire from the ground bar on the interior panel to the meter enclosure is good practice or a potential hazard. I am aware that you are effectively paralleling the grounded conductor in doing so and that most meter enclosures are factory bonded from the can to the grounded conductor. I am also wondering if there would be any potentially hazardous current flowing through the #4 wire (I'm assuming there is, since electricity takes all paths; not just the path of least resistance) or if the resistances of the two wires are different enough that the current flow would be miniscule. My second question is: if there is a loss of the grounded conductor on the poco's side, what measures could be taken to reduce the potential of the meter enclosure and/or the GEC from becoming the path back to source? I am a city electrical inspector and would like things to be as safe as possible, with respect to practicality. Thank you, in advance, for any comments regarding these matters.

 

[iwire]

Running the additional conductor would be violation of the NEC rules for parallel conductors.

Short of requiring the power company to provided separate grounding and neutral conductors nothing can be done.

 

[infinity]

If there is a metallic public water system and the GEC connection to the water pipe is good then the loss of a utility neutral might go completely unnoticed as the neutral current will return on the water pipe through the neighbors house. As Bob stated creating a violation to mitigate a problem that has a minuscule chance of occurring is not a good idea.

 

[Smart $]

Running the additional conductor would be violation of the NEC rules for parallel conductors.

I was of the impression that parallel conductor rules of 310.10(H) do not apply to bonding jumpers (aka grounding conductors).

 

[Smart $]

... My second question is: if there is a loss of the grounded conductor on the poco's side, what measures could be taken to reduce the potential of the meter enclosure and/or the GEC from becoming the path back to source?...

It would be illegal to make a metal water pipe electrode not an electrode... but I have heard of situations where the owner had the plumbers install non-metallic fittings in the water line at 10' out from the building footprint to effectively isolate the water pipe electrode from the municipal main.

 

[GoldDigger]

I was of the impression that parallel conductor rules of 310.10(H) do not apply to bonding jumpers (aka grounding conductors).

The parallel conductor rules do not apply to the GECs and bonding jumpers themselves. But downstream of the service point you do not want an EGC or bonding jumper to be parallel to the grounded conductor. That would cause it to carry not just fault current but normal current too.
There are very specific rules about redundant bonding wires in the meter and main disconnect cluster.

 

[Smart $]

The parallel conductor rules do not apply to the GECs and bonding jumpers themselves. But downstream of the service point you do not want an EGC or bonding jumper to be parallel to the grounded conductor. That would cause it to carry not just fault current but normal current too.

You are preaching to the choir if that's directed at me.

There are very specific rules about redundant bonding wires in the meter and main disconnect cluster.

Please cite section(s).

 

[iwire]

I was of the impression that parallel conductor rules of 310.10(H) do not apply to bonding jumpers (aka grounding conductors).

But it does apply to grounded conductors.

You say the added conductor is a bonding jumper, I say its an additional grounded conductor.

 

[Smart $]

But it does apply to grounded conductors.

You say the added conductor is a bonding jumper, I say its an additional grounded conductor.

Electrically they will be parallel. Depends simply on size and marking, insulated or not. Bare conductor will definitely not be a grounded conductor.

 

[ActionDave]

But it does apply to grounded conductors.

You say the added conductor is a bonding jumper, I say its an additional grounded conductor.

Electrically they will be parallel. Depends simply on size and marking, insulated or not. Bare conductor will definitely not be a grounded conductor.

Are you two sure you know what the OP is talking about? I'm not.

I am wondering if running a separate wire from the ground bar on the interior panel to the meter enclosure is good practice or a potential hazard. I am aware that you are effectively paralleling the grounded conductor in doing so and that most meter enclosures are factory bonded from the can to the grounded conductor.

Extra neutral or required equipment ground? Which is it?

 

[iwire]

Electrically they will be parallel. Depends simply on size and marking, insulated or not. Bare conductor will definitely not be a grounded conductor.

All that is opinion, as was my post. It will be up to the inspector.

You can not say size indicates the use as the size chosen could simply be looked at as incorrect.

But would you add this conductor or not?

 

[iwire]

Are you two sure you know what the OP is talking about? I'm not.

Try to catch up.

 

[kwired]

If you add a second conductor (whatever you decide to name it), it will carry normal operating current. Should the "grounded conductor" someday fail - this second conductor will take over essentially becoming the grounded conductor. But you will have no indication the original grounded conductor failed and will still have same kind of conditions should the second conductor fail as you would have if there were only one conductor in the first place. You maybe bought some time before total failure - but is really an un-determinable amount of time that can't really have any value put on it.

Single conductor may never fail either you really have no way of telling.

JMO.

 

[Smart $]

All that is opinion, as was my post. It will be up to the inspector.

You can not say size indicates the use as the size chosen could simply be looked at as incorrect.

But would you add this conductor or not?

Likely not if it is my choice. But no one seems to have a problem with it when it's in the form of a metallic raceway.

 

[Kaybeeoh84]

Thank you for your responses. We will be requiring the electricians NOT run the separate wire. Now we (me and the other electrical inspector) have to convince the poco's in this area that it's a bad idea lol Wish us luck! :lol: