Any Electricians/Electrical Contractors Here?
 

Need guidance on supply cable and conduit sizing. Here's the specs:

Service: 200A, 240V single phase
Distance: 275' from meter to distribution panel
Location: underground
Conduit: PVC

My questions:
What cable size?
What conduit size?

Wire Size:
125A service needs #2 copper or 1/0 aluminum -- #6 copper ground.
150A service needs #1 copper or 2/0 aluminum -- #6 copper ground.
200A service needs 2/0 copper or 4/0 aluminum -- #4 copper ground.

3" conduit would probably be a good idea, and using wire lube while pulling it

Thank you!!!

No problem. :) I'm not an electrician, but I found another site where a guy asked an electrician the same question, and I merely stole the electrician's answer. :D

Hmmm. Well, you and I must have found similar sites because that's the same answer I came up with. I just wanted to confirm my finding with info from someone in the trade.

When I ran the underground utilities to this cabin, I accidentally undersized the PVC conduit. Even with gallons of wire soap, when we pulled the cable there was so much friction, there were a few times that I was concerned about actually ripping the whole 300+ feet of conduit out of the ground.

I'm trying hard not to duplicate that fiasco.

3"? Most 200a services are 2" or 21/2". I am a counter guy at an electrical supply. I could double check these internet guys with some of my master electrician buddies. I might also check on voltage drop at said distance. Go copper if affordable. If you are, buy now. Its starting to go back up steadily!

As a guy who has done my fair share of electrical work, my input is - Go Big -
There is just no substitute for wire that is bigger than needed. It costs more, but the security of knowing that you haven't just planted a toaster element in the ground is priceless. Last run I did that size I ran 3/0, (run was 350') partly due to the homeowner paying for material, partly because that was what run from the pole (500') to their main panel, and partly due to the lack of a solid answer about the usage they were planning at the barn. Of course I am also the guy who has never and will never run 14 ga wire for anything.

I dont know about where you live, but in San Antonio, running 14/2 romex in houses is illegal.

We just pulled similar size wires through about 115' of underground conduit. I was shocked at how difficult it was to pull the wire.

Run the conduit in a way that minimizes the number of bends. Have one or two people pushing the wire in at one end while someone pulls from the other. I used a boom mounted on my tractor's 3-point hitch to pull the last 10 feet or so of wire. That's how hard it was to get that heavy wire to go through the bends I had in my conduit. Man, was I relieved to see that wire finally poke through the end of the conduit.

NEC says 14ga is acceptable for 15amp. Don't know what code book they got down there, but NEC is pretty much the law everywhere I've built. All that aside, I don't use it. You just never know what some moron will do somewhere further on down the line, and I don't like to see things I've built burn down.

The rule I've seen my electricians use for conduit runs is nothing over a total of 360° worth of bends or you need another pull-box.

When pulling the underground stuff, if you can put the bends on AFTER you've pulled the cable through the long run, that would be the way to go.

I had to pull 3 sets of paired 4/0 through 45 feet of 3" conduit, from a new power transformer's location to the to-be-installed CT Panel's location on the outside of the building...wrestling with that crap was fun (25° F). But, after the wire was pulled and enough leader was left on both ends, we then threaded the elbows on, and stubbed up the excess...the new transformer platform and transformer dropped right over the tails and the CT cabinet stubbed right on top of the three threaded ends of the 3" tubes coming up at the building...thank you GOD we didn't pull the cable with those elbows and stub-ups on!

You'll never hurt yourself going up one guage size in wire from what's initially mentioned...particularly on long runs and when you're looking at higher amperage. The less loss you experience in the run also translates in lower electrical costs. Whether you use the juice or heat up the conduit with the smaller guage wire, you'll still pay for anything (including the heating of the conduit) down-wire from the meter. We went that extra guage up when we did the new service for our transmitter plant...a small investment that won't come back and bite us in the @55 later on...

Yep. New codes are now being implemented to protect us from ourselves. Now all receptacles shall be tamper resistant and pretty soon all single pole circuits will be arc faults combination type. That raises the price from bout $3.5 a breaker to about 32 each. 14 g is used outside the city all over to keep costs down, but SA wont allow it. Not sure I understand why they require the use of 12 ga wire, 20A breakers and only 15A receptacles?

* - First, the receptacle should be able to inhibit the insertion of a 20Amp. appliance. Should that fail...

* - 2nd, the 20A breaker should pop before the...

* - 3rd item, the 12 ga., wire heats up to the point of melting down and starting a fire in the wall/ceiling where it's laid/stuffed/hiding.

Personally, I'd rather replace the outlet or breaker...burnt wiring sucks...I had the fun job of removing melted wiring from the wall of a "Wausau Home" one time...the only thing that kept that pile of tinder from going up (as it should have) was the idiot that did the wiring (Improperly...he went down in guage size, not UP! :eek: :rolleyes: ) was the fact that when he stuffed the insulation back in, he also hermetically sealed the plywood back on the studs and effectively smothered the flames due to lack of oxygen getting behind the wall and feeding the burning plastic and insulation (Yes, the insulation burned/melted too!).

I don't know if he's killed anyone yet...the guy was an idiot then and I don't think he's much changed...TG I haven't see him in over 25 years to find out... ;)

you wont believe the amount of people that seem to wake up and go." I think I'll be an electrician today." or the people that come in and are building a house and they hire their friends to wire the house to save money. They come in and ask what wire size this and what that, and I tell them the best thing to do would be to ask their electrician. They tell me "Oh we hired our dump truck driver to do it because the electricians cost too much." I am no electrician. I cannot give advice to them even if I knew. The home Depot dudes will tell you all day long, but I can't.

I asked one electrician and he suggested using 3/0 copper at least.