I need to run a 250 foot buried line to bring power to a small cabin.
For this application, is there any reason to be concerned about using
aluminimum wire instead of copper? Copper will cost me twice as much
and, for this distance, aluminum provides very significant savings.
The electrician reports the main hazard as corrosion if the conduits
are not well sealed and/or if the integrity of the insulation is
Aluminum doesn't conduct electricity as well as copper, so you'll need a
larger wire size (i.e. 4/0 for 200 amps, instead of 3/0 copper). But, the
cost for aluminum is much lower overall.
The main problem with aluminum is surface oxidation when it is exposed to
the air. This won't be an issue along the length of the cable, but it can
increase resistance at the connections, building up heat, and potentially
start a fire.
For that reason, aluminum is rarely used for indoor wiring anymore, but
around here at least, aluminum is just about the ONLY way cable is run
underground these days. The cables are generally made for direct burial.
You shouldn't need the conduit, unless you can't get the required depth for
some reason (rock or something).
When you connect the aluminum cable to your breaker panel, you must apply a
special anti-oxidant paste to the cable and connection to prevent the
oxidation problems. Once that's done, it's as trouble free as copper.
I'd be willing to bet that the main service line installed by the power
company from the transformer to the meter is aluminum for 99% of the houses.
I'm burying aluminum wire to get power to my new shop next week. Direct
burial, no conduit except at each end to get into the buildings.
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