Silly question

[RichB]

Ok here goes--We have a contractor that wants to use triplex for the following installation and something is telling me no but I can't find it ---
120/240 single phase service (this is a service for lighting and traffic signals)

They want to pull in triplex from the POCO utility pole underground through conduit into our service and terminate at the meter can.

I can't get an answer as to why they don't want to pull in USE single conductors as we normally do (2 hots and a neutral)

I would think that we would want the neutral conductor to be insulated though again I cant find anything that specifically says so.

As an agency we are going to disallow this as it does not meet our spec and drawings--but I was just curious and you folks always seem to have the answer!
Thanks!

 

[fmtjfw]

He must have a lot of triplex left over from something. Has he ever tried to pull triplex through conduit? Between being twisted together and being much stiffer than building aluminum wire....

Is he planning to use overhead triplex or URD (underground Residential Distribution) cable?

 

[augie47]

For one thing, utility triplex is not a recognized NEC wiring method (310.13) and it would also not meet the requirement of 230.30

 

[GoldDigger]

But it is on the POCO side of the service point, for what that is worth, so another question is how POCO feels about it.

Tapatalk!

 

[ptonsparky]

ACSR overhead type triplex or direct burial?

 

[RichB]

don't know what kind of triplex--they just said triplex!!!

augie47--Iwas looking under services--never thought of going there!!
Thanks guys!!!

 

[meternerd]

Probably just a terminology issue. Utilities call the three wire twisted service wire triplex for single phase and quad for three phase. That does not mean Romex.

 

[RichB]

meternerd--You are correct --and our contractor was talking the triplex you mentioned as for a single phase service

 

[mwm1752]

There is triplex with an insulated grounded conductor . The way he described the triplex he mentioned the grounded conductor is uninsulated which I think was called out as utiliy triplex in another post. some call it a concentric ground.

 

[meternerd]

There is triplex with an insulated grounded conductor . The way he described the triplex he mentioned the grounded conductor is uninsulated which I think was called out as utiliy triplex in another post. some call it a concentric ground.

Overhead triplex has a bare neutral. Underground triplex has an insulated neutral (usually smaller and marked with a stripe). Ditto for quad.

Concentric usually refers to underground primary cable where the neutral conductor is wrapped around the outside of the phase conductor. It can be open concentric (no jacket over the neutral, or "uni-shield where the neutral is covered by a jacket). Open concentric is old school because the bare conductor can be damaged by rocks, corrosion, etc.