since i have a back hoe available for awhile. i am running a new 3 wire line to the barn. just wondering what is the benefit of copper over aluminum and vise versa.
( i understand copper is a lot higher in price atm)
it's about a 100 foot run, open to any recommendation as to size and type, and what else i should drop in the trench. running a water line for sure.
thanks in advance for any pointers.
can not remember if i have 100 or 150 amp service out there, i will check it in the morning.
Lot of information requested here....so let's dissect it.
I'm going to assume this will need to be inspected, therefore, my response is based on ICC codes; so double your local first.
1) Our local code says that you can bury electrical and plumbing in the same trench provided: a) the entire electrical circuit is in conduit or... b)the direct burial cable is separated from the plumbing by 24", side to side distance.
2) Cable choices, again in conduit, cable "type" (not conductor material) is of no concern. If it's not in conduit, you'll need direct burial cable. If you do use direct burial, when it exits the ground, make sure the conduit extends at least 18" below ground.
3) Copper is
the best to use. The problem with aluminum is that when electricity flows through it, it heats up. No electricity, it cools down. This causes the aluminum to expand, retract, expand, retract, expand, retract, on and on and on
....you get the picture. Therefore, over time, as others have suggested, if not properly torqued and installed, it has the potential to come loose and possibly cause a fire. THIS IS THE REASON 100%OF ALL INTERIOR WIRE IS COPPER (at least Louisiana code).
Why aluminum as power service entrance? It's pretty simple, it's under a constant load, as some device somewhere is pulling amperage across the lines. No heating up and cooling down periods. In Louisiana,
99% of all power service entrance cable is aluminum and with virtually no problems.
In Louisiana, aluminum is not allow on branch circuits (the homes interior circuits. It's just too dangerous.)
4) When sizing wire, some factors need to be considered; much of the info required to size was not mentioned. Therefore, below is a little electrical matrix that should put you on the right path.
Constant = 100' run (you need to account for voltage drop at that distance)
120V Service
100 amps needs #4 copper or #2 aluminum
150 amps needs #2 copper or 1/0 aluminum
200 amps needs #1 copper or 2/0 aluminum
240V Service
100 amps needs #6 copper or #4 aluminum
150 amps needs #4 copper or #3 aluminum
200 amps needs #4 copper or #2 aluminum
5) What else to run in the trench? Have you considered cable/satellite wiring, CAT6 maybe for internet from the house? Smartest is to lay 1 size larger conduit and run some cable pulls through it. That way at a later date, it's pretty simple to pull "what-ever" cable you need through the conduit.
Hope this helps out.
Also, if the matrix doesn't cover you sizes, here is a simple calculator that can help you out.
http://www.csgnetwork.com/wiresizecalc.html