Single-Wire--Earth-Return

[winnie]

Jon, doesn't that apply to all distribution circuits? Or are you saying that the messenger is not tied to the source neutral?

It applies to all distribution circuits; the MEN is tied to the source neutral.

Simply with all 3 phases you tend to have balance and thus lower current on the neutral; with a single primary phase _all_ the current has to return on the MEN, and thus more will make it on the parallel path.

-Jon

 

[Eddie_T]

SWER is rarely used anymore, and almost definitely not installed anymore, but was probably installed long before aluminum wire was around.

I recall (maybe from college) that steel wire was used to run SWER to remote sites such as a USFS fire watch tower.

That is actually common, especially in the city (Richmond); one grounded conductor used for both primary any secondary neutral purposes.

The primary current would be quite low, just a few amps compared to house neutral.

Has anyone measured grounding current for a typical residence? There would have to be some as it is a parallel path (in the milli-amp range?).

 

[mbrooke]

The reason I ask is that a National Grid (serving PA, NY, NJ, CT & RI) customer posted a comment on a YouTube channel that the pole serving him has only 2 wires, the 7200v line and the telephone cable and the pole ground ground completes the circuit for the transformer primary. I was trying to find an explanation for what he observes and can't think of one unless the single 7200v wire happened to be a metallic sheathed cable (but I don't know if that is used for anything other than direct burial).

Being Youtube, consider trolling as a possible motive. Or someone refusing to admit they were wrong. See it all the time where none experts will comment on something, end up being proven wrong, only to then say what ever they can to appear right.

BTW, NG does not serve any load in CT, NJ and Pennsylvania. There outage map shows the areas served, just zoom out to see the territories:


https://www.nationalgridus.com/Upstate-NY-Business/Storms-Outages/Outage-Map