[AJ1974]

Can someone verify my thinking. I have a 400 amp service run is <100'

1- 4/0 triplex should be enough for the max rating no?

 

[brric]

No. Violations on you feeder terminations as well.

 

[betelgeuse]

Can someone verify my thinking. I have a 400 amp service run is <100'
1- 4/0 triplex should be enough for the max rating no?

Heck no. 4/0 Aluminum is only rated for 180 amps

 

[Oldmaster]

4/0 THHN on a messenger in free air rated at 224 amps.

 

[betelgeuse]

4/0 THHN on a messenger in free air rated at 224 amps.

It's not in free air. The free air rating is for individual wires. Since this is triplex, it's a cable and it doesn't apply.

 

[AJ1974]

No. Violations on you feeder terminations as well.

Yes and this why I'm second guessing the licensed electrician that I hired. The inspector told me they need to be on one lug.

So do I need to buy two 4/0 tri-plex?

 

[AJ1974]

It's not in free air. The free air rating is for individual wires. Since this is triplex, it's a cable and it doesn't apply.

Ok now I'm learning a bit more. I don't know where to get into and out of the tables. But this helps. Thank you!

So is it better to pull two 4/0? But the meter can looks like it would receive one set.

 

[brric]

Usually the POCO is responsible up to the meter. Are there special circumstances here?

 

[seharper]

Yeah, VERY different rules for the PoCo on the PoCo side of the meter. They don't even follow NEC, they have their own codebook.

 

[brric]

For underground laterals, if a dwelling unit, paralleled 4/0 aluminum XHHW conductors would suffice. Other than a dwelling unit, paralleled 250 mcm XHHW conductors. Lugs in cabinet can be changed to accept multiple conductors.

 

[betelgeuse]

So do I need to buy two 4/0 tri-plex?

Service wires and feeder are required to be 83% of the rating of the service.

400Ax.83= 332A. If it's the sole supply to a residence yes.
If not you'll need to use 2 paralleled 250KCM.

 

[seharper]

Yes and this why I'm second guessing the licensed electrician that I hired. The inspector told me they need to be on one lug.

So do I need to buy two 4/0 tri-plex?

No, no, no! You can't "just up-and decide to parallel". Since you are under NEC, paralleling requires a bunch of factors, including special equipment on the source side. Don't even dream of taking it on as an amateur, and the essential ingredient is a special cabinet rated for paralleling at the source.

Your best bet is to do it in one wire, so go up beyond 4/0 into the kcmil aka MCM wires, e.g. 1000 kcmil. And you definitely want to be in aluminum at that point.

I had to pay for 100' of 1000 kcmil copper to go 15 feet. You don't want to do that lol. (long story, Al wire would have been too big for the conduit, and since >1000kcmil Al is hard to find, it would've required triple-paralleling, and the special equipment we had was only equipped for 2 parallels. The special equipment included 6 fuses the size of a Magnum beer can.)

Service wires and feeder are required to be 83% of the rating of the service.

Only in NEC land. Power companies follow NESC. Totally different. Like French and German.

 

[Oldmaster]

Actually table 310.15(B)(20) days not more than 3 single insulated conductors in free air. It is not a cable unless it has a overall outer covering.

 

[Oldmaster]

Dual 4/0 per phase will work for 400 amp.

 

[AJ1974]

Usually the POCO is responsible up to the meter. Are there special circumstances here?

Yes, that's why I am out of my element. I am supplying the material and the electrician will be here on Sunday. At this point I am second guessing everything he says because it has been contradicted by others.

 

[AJ1974]

Dual 4/0 per phase will work for 400 amp.

Thank you and to everyone else.

 

[Wiredindallas]

So exactly is this situation? Are you talking about the service drop from the POCO source to their meter? If so, why is it your concern or responsibility?

 

[AJ1974]

So exactly is this situation? Are you talking about the service drop from the POCO source to their meter? If so, why is it your concern or responsibility?

Normally it is not my concern. In this case it is. I am supplying the material labor and ditch from the meter to the pedestal. Trust me, I prefer that I didn't.

 

[Oldmaster]

Triplex as designed for overhead use. If you're going underground from a meter to a pedistal you are going to use conduit and conductors or USE conductors. Triplex cannot be buried.

 

[seharper]

Honestly, if somebody held a gun to my head and told me it HAD to be in this week and it was OK to waste material to git-r-dun, I would use the 83% rule from 310.15(B)(7) giving 332A, and pick the appropriate aluminum kcmil sized conductor (600kcmil, maybe 500 if you can justify the ole "round up to the next available breaker" rule).