Ask Experts Questions for FREE Help !
Ask
    hiohsilver's Avatar
    hiohsilver Posts: 1, Reputation: 1
    New Member
    		  
    #1

    Sep 19, 2007, 07:37 PM
    What size aluminum to use, triplex?
    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
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
    Uber Member
    		  
    #2

    Sep 19, 2007, 08:36 PM
    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.
    laph's Avatar
    laph Posts: 1, Reputation: 1
    New Member
    		  
    #3

    Sep 19, 2007, 10:27 PM
    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
    donf's Avatar
    donf Posts: 5,679, Reputation: 582
    Printers & Electronics Expert
    		  
    #4

    Sep 20, 2007, 03:32 AM
    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
    ranijeee's Avatar
    ranijeee Posts: 1, Reputation: 1
    New Member
    		  
    #5

    Oct 28, 2011, 08:46 AM
    What are the uses of triplex wire?
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
    Uber Member
    		  
    #6

    Oct 28, 2011, 09:06 AM
    Typically used as aerial cabling pole to pole.

    Quote Originally Posted by ranijeee View Post
    what are the uses of triplex wire?
    stanfortyman's Avatar
    stanfortyman Posts: 5,598, Reputation: 279
    Electrical & Lighting Expert
    		  
    #7

    Oct 28, 2011, 01:08 PM
    Some people call direct burial URD triplex as well. No one in my areas does though.

    ranijeee, why do you ask?
    HickoryHollow's Avatar
    HickoryHollow Posts: 1, Reputation: 1
    New Member
    		  
    #8

    Sep 14, 2013, 01:13 PM
    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.
    stanfortyman's Avatar
    stanfortyman Posts: 5,598, Reputation: 279
    Electrical & Lighting Expert
    		  
    #9

    Sep 14, 2013, 01:33 PM
    HickoryHollow, what are you replying to? The posts made two years ago or the ones made six years ago?
Not your question? Ask your question View similar questions
 

Question Tools Search this Question
Search this Question:

Advanced Search

Add your answer here.


Check out some similar questions!

Full size headboard, Queen size bed Frame [ 2 Answers ]

Where can I buy attachments that will allow me to fasten my full size headboard to my queen size bedframe? I am having a bit of trouble finding one.

HVAC issues in triplex [ 7 Answers ]

I own a very old home that was converted into a triplex during the housing shortage in the 40's. At some point a central heat/air conditioning unit was installed which services the entire home, and where both cold air return ducts are located in only one of the units (the larger side that I...

Compatibilities between awg wiring, breaker amp size, outlet amp size [ 4 Answers ]

Hi. Is there a resource out there, prefereably on the web, that outlines the compatibilities between awg wiring, the breaker amp size, outlet amp size, how many recepticles/outlets can be on x amp outlet, etc? For example, it would be nice to see something that shows: you can use a 20 amp...

Aluminum or copper? [ 6 Answers ]

My husband and I recently acquired a hot tub. We would like to install every ourselves but are totally green on the subject. So, we have decided to at least purchase the materials and have an electrician just hook it up to the box. What type of wire should we buy. I know it is 6/3 but the hardware...

Aluminum Feeder Terminations [ 1 Answers ]

As a commercial electrician I was taught that terminations of Aluminum feeders had to be periodically checked for tightness due to 'creep' (the wire expanding and contracting due to changes in temperature). Is this a real problem? What is the recommended interval for checking the proper torque of...

View more questions Search