above ground outdoor wire

[stavpeter]

I need to replace a very old wire running from a 50 amp breaker in my main service then up a wall and to the outdoors 14 ft above ground, then in the air about 25 feet to a sub panel in an outbuilding. Total length of the wire from main to sub is about 50 feet. Can I use 6-3 UF wire rated for underground, or do I need some other type? The current wire is an extremely old 3 wire whose type I cannot see.

Thanks.

[HayZee518]

The input to a sub panel needs to be a four wire cable. type uf is meant for below grade. 4/4 SER would be the cable to use. aluminum cable is always one size larger.

[stavpeter]

Appreciate the info. So I just replace the 4 existing wires (existing cable is 2 hot, neutral plus ground) putting each wire from the new 4/4 cable in the identical location that the same old wire was located in the main panel, then run the new cable on the same path to the existing sub panel and again put each wire from the new cable in the identical location of each of the wires from the old cable. Right?

Thanks again.

[HayZee518]

basically, yes. at the main panel the earth ground and neutral goes on the neutral bar in the main, the two hots go to the sub panel breaker feeder. at the remote panel, the white neutral goes to the neutral bar [no bonding screw or jumper is used] the bare ground to the equipment ground bar and the two hots to the sub lugs or to a backfed breaker, whichever you have.

[stavpeter]

I keep reading that aluminum wire expands and contracts and oxidizes. Could I use a 6/4 copper service entrance wire instead of the 4/4 aluminum if I were willing to pay the price? Do you think that is worth extra money given that line will run about 25' in the air in a cold climate?

Thanks again for your help.

[HayZee518]

All wires expand and contract. The oxidation occurs where the aluminum is in free air. That's the reason for using an anti-oxidant at wiring terminals. The aluminum will not oxidize within the cable sheath. code book says 6-4 THHN, THWN will carry 65 amps. If you get a cable make sure its rated for outdoor duty, sunlight resistant SER. Another type cable is called TRIPLEX. It is an assembly of three conductors AND a steel reinforced messenger cable which also suffices as an earth ground wire. Triplex is used by the power company to go from a pole. across a road or grade, to the service entrance point on a house. It is then spliced to the service entrance conductors be it aluminum OR copper with pressure applied butt splices.

[stavpeter]

Thanks again for the help.

How does this look for the wire I need with a little extra capacity in case breaker size on feed might want to be upped in the future?

"Hackney 4 xlp quadruplex service drop 4awg 600 volt aluminum" for $1.80 per foot for the 50 feet I need?

[HayZee518]

type xlp means cross linked polyesther, quadraplex is four conductors within a jacket. run it in a continuous length no splices. where it'll be subjected to mechanical damage sleeve it in pvc conduit and penetrate the house with an LB fitting. at the point where the vertical changes direction to horizontal, use a screw in porcelain insulator and a strain relief fitting, same at the remote location.