Hello,

I am running a subpanel in my detached garage, 240v 100 amp panel. Distance is 170 ft. Direct burial, no conduit. Wondering what size/type aluminum to go with, 2/0 or 4/0, to comply with NEC code? By code I need the 4th (ground) wire because I will also be burying cable and data wire. Does this mean I should use "quadplex" or just use a 6 ga direct burial copper plus triplex? That 6 ga copper alone is running $.83/ft. Triplex $2.17/ft. Do I need 6 ga copper or can it be smaller? Not sure what application quadplex is for, maybe cheaper, no copper? Also what is the code for size of ground rods now, 5/8? I guess I need two per building 6ft or more apart?

Much Appreciated

What size wire will depend on one, the amp rating of the circuit, the calculated load, and figure in the distance.

For 200 amp residential feeder, without figuring in voltage drop min size wire is #2/0 copper or #4/0 aluminum.

A 4 wire aluminum cable ,or quadriplex, is available for direct bury, called URD (Underground Residential Distribution) cable. Very popular with feeding homes when the meter is on the pole, or subpanels in outbuildings.

You can use triplex, with an added wire for the equipment ground, but a bit unorthodox.

Min size ground rod is 8 foot long x 5/8" diameter. At least one rod is needed, but not at the subpanel, only at the enclosure containing the main breaker, or at the meter trim. More than one may be needed depending on soil conditions, to keep ground resistance at a maximum of 25 ohms or less. Special equipment is needed to measure this resistance, so many inspectors require at least two rods. Need to check with local inspector on this.

I would like to install a 125A sub panel. It is located 175' from main 200A circuit panel. What aluminum size wire do I need or What copper size wire do I need?
What conduit size for aluminum wire and what conduit size for copper wire?
Are there any other considerations for this installation?

Thanks,

Lan

Lan,

A couple of things I have recently learned here:

#1, Please do not start a new question within an existing question. Start a new inquiry.

#2, I believe that single phase 3/0 cable is rated right at 125 Amps. There is very little
Margin for safety. You really should look at the 4/0 alum. Cable.
#3, Do your math you say you have 200 Amp service to your home panel and that you
Want to be able to pull as much as 125 Amps off to your sub panel, which will leave
75 amps of service for your home service. How is that going to be enough amperage
To sustain your home and sub panel?

As in the previous question, I suggest you call your local inspectors to find out if the will allow that much of a draw off the house panel and then issue you a permit to do the work.

You also have to consider whether you would have to change the panel box to allow for the cable to service the sub panel. If the existing box is a two lug box, you will have to add a double lug adapter to each service bus bar in the primary panel box. Right there would be a show stopper for me. There is no protection for you when working on the Service In cables. You could very easily become a glow in the dark crispy critter.

Call several licensed electricians to give you a quote on installing the sub panel as well as running the service to it. If you are sure of what you are doing, you may be able to finish off the wiring from the sub panel box to

What are the uses of triplex wire?

Typically used as aerial cabling pole to pole.

Quote:

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Originally Posted by ranijeee

what are the uses of triplex wire?

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Some people call direct burial URD triplex as well. No one in my areas does though.

ranijeee, why do you ask?

What you are saying doesn't really make sense. Think about it... you might have 12- 20 amp breakers, 6-15 amp breakers, a 30 amp breaker for your dryer, and a 50 amp breaker for your kitchen stove, all in a 200 amp breaker box. He isn't going to be drawing all 125 amps at one time, plus another 75 amps in the house.

HickoryHollow, what are you replying to? The posts made two years ago or the ones made six years ago?