opinion on THHN/THWN for service entrance conductors

[mshields]

I'd be interested in your collective opinion. Do you think for incoming service conductors run in conduit from the utility transformer to the service disconnect inside the building, that THHN/THWN is adequate insulation for the job OR would you typically use something more robust such as RHW or XHHW.

What do you think is the best practice?

 

[chris1971]

I'd be interested in your collective opinion. Do you think for incoming service conductors run in conduit from the utility transformer to the service disconnect inside the building, that THHN/THWN is adequate insulation for the job OR would you typically use something more robust such as RHW or XHHW.

What do you think is the best practice?

If it's code compliant for the application, then yes I'd consider using it.

 

[ptonsparky]

RHW and THWN are typically stocked in our area supply houses so that is predominantly what is used. XHHW is available and cut to length within a few days of order.

 

[ActionDave]

THHN/THWN is fine.

 

[electrofelon]

Around here, and many other places it seems, most stocked copper is thhn while AL is xhhw. Not sure why that became so common. If I was ordering it and had my choice, I don't think I would care much either way for most applications. For orders of colors, a place I use used to get thhn, but as of recently they can also get xhhw too.

Anyone know the cost difference?

 

[petersonra]

I don't think it makes any real difference as long as you can get what you need. Seems to me a lot of service entrance conductors are aluminum and I don't even know if you can readily get aluminum in thwn.

Eta - now that I think about it some more I'm not even sure I've ever seen thwn in aluminum.but mostly I deal with copper.

 

[peter d]

We use AL XHHW the vast majority of the time, and that's been standard practice in my area for many decades now.

 

[chris1971]

We use AL XHHW the vast majority of the time, and that's been standard practice in my area for many decades now.

Aluminum is definitely the way to go unless the job specifies copper.

 

[chadnodine]

Yes. I think Alu is fine with either type. Just be careful. When you are bring the service conductor inside a building there are limitations on distance to your over current protection and it depends if it's underground stubbed up or even shorter if not. If you have over current protection outside the building then you are ok.


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[peter d]

Aluminum is definitely the way to go unless the job specifies copper.

I agree, copper is a waste of money.

 

[jumper]

I don't think it makes any real difference as long as you can get what you need. Seems to me a lot of service entrance conductors are aluminum and I don't even know if you can readily get aluminum in thwn.

Eta - now that I think about it some more I'm not even sure I've ever seen thwn in aluminum.but mostly I deal with copper.

Yeah they make it and not super hard to find, depends on size needed and area location.

It is usually dual rated THHN/THWN-2.

 

[mshields]

thank you all

thank you all

I appreciate all the inputs!

 

[brantmacga]

Almost all of our jobs spec THHN copper service conductors ....... I only see XHHW spec'd when it allows AL.


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[jminer99er]

I like xxhw just for the cut-through value on the insulation, but its more flexible and does push as easy. A roll of #10 xhhw2 is around $30 more than thhn

 

[NewtonLaw]

Utility Design Exoerience

Utility Design Exoerience

I am not sure which Utility you are speaking of, but my Utility, PPL Electric Utilities Corporation, is responsible for extending the service conductors to the service weather head for OH supply and to the meter box or CT cabinet of underground supplied services and they use XLP or XLPE almost exclusively. In areas where the Utility requires the customer to install the service conductors from the utility transformer location the NEC rules apply.

Hope this helps,

Newton Law