Equipment Grounding Conductor Size in SER Cable

[GeorgeB]

There is a theory that the ground wire should be insulated and not used as a support wire.

I've never heard that theory, but IME, if used as support it will be ACSR, not just aluminum.

 

[mtnelect]

You have to go back to the pole transformer where the phase to neutral primary connection with secondary winding center tapped and the primary neutral solidly connected to the secondary neutral. This matches the service drop.

This is only theory. I have to do more research to verify this.

 

[electrofelon]

You have to go back to the pole transformer where the phase to neutral primary connection with secondary winding center tapped and the primary neutral solidly connected to the secondary neutral. This matches the service drop.

This is only theory. I have to do more research to verify this.

One theory/proposition is that the utility run separate N-G conductors to a structure and the N-G bond is at the transformer. That would have some theoretical safety advantages, but in my opinion very very small.

The MGN distribution system has issues with stray current so there are some people who advocate against that

Regarding Connecting the primary neutral of an mgn to the secondary neutral, there are some theoretical negatives to that practice.
Essentially is it a selfish matter by the utility to utilize the customer's premise grounding for any incidences that occur on the utility's system, and thus potentially imposing medium voltages into the customer's premises. That connection does not have to be made, it's just a matter of the transformer construction, i.e. the tank being the neutral connection for both systems. There is a device called a Ronk blocker which could help mitigate those effects yet still allow the advantages the POCO receives from connecting the primary and secondary neutrals.

So anyway, I see those as three separate issues.

 

[wwhitney]

Regarding Connecting the primary neutral of an mgn to the secondary neutral, there are some theoretical negatives to that practice.
Essentially is it a selfish matter by the utility to utilize the customer's premise grounding for any incidences that occur on the utility's system, and thus potentially imposing medium voltages into the customer's premises. That connection does not have to be made, it's just a matter of the transformer construction, i.e. the tank being the neutral connection for both systems. There is a device called a Ronk blocker which could help mitigate those effects yet still allow the advantages the POCO receives from connecting the primary and secondary neutrals.

But if both primary and secondary neutrals are earthed, they will be connected via the earth. So what are the implications of directly connecting them, vs just letting them be connected via the earth?

Cheers, Wayne

 

[electrofelon]

But if both primary and secondary neutrals are earthed, they will be connected via the earth. So what are the implications of directly connecting them, vs just letting them be connected via the earth?

Cheers, Wayne

I would say the dirt is a relatively poor conductor, so a solid low impedance connection will direct higher voltages and currents into the building.