Aluminum service wire

Buckcreek · Jan 14, 2006

I was pricing wire for service to my poll barn , aluminum service wire was around $300. and copper was over $1000. My Dad does not like the idea to use aluminum but i believe that is all i can afford. what to the electricians on here think about it. The aluminum wire is for 100amp service it will be ran from a 200 amp service for a mobile home . it will be close to if not a little more than 300'. The man at state electric store said it would work very well. How will this affect power in my home.

EdKing · Jan 14, 2006

The only concern with aluminum wire is to make sure the hardware is specified for use with aluminum. If the terminals are not specified as "for use with aluminum" you can get dissimilar metal corrosion, leading to heat build up and possibly a fire. Also make sure you use a corrosion inhibitor on your hookups.

EddieWalker · Jan 14, 2006

Due to the price difference, allot of people use aluminum over copper with great results. Copper is better, but with so much aluminum out there being used in just about every application, it's not something to shy away from.

Some of the concerns and complaints about aluminum is the oxidation at the terminals. This causes them to loosen up over time and you end up retightening them every year.

To eliminate this I use an oxide inhibiting compound called Contax. It's a thick black fluid that you just put on the exposed wire before tighting it down.

I bought it at the electric supply house and have never looked for it at the box stores. Not sure what they have or if it's as good.

The other issue with aluminum is you have to use thicker wire for the same run compared to copper. It's still cheaper, but you have to make sure your comparing the same capacities of the wire, not the size.

Eddie

Buckcreek · Jan 14, 2006

The wire he quoted me was suppose to be the proper size for the application. It was , I think #2 service wire. It had three runs of copper wire and another run of a green covered wire for ground . it was direct burieal wire. but if i use it i will still put it in pvc. He said it was 100 amp service wire.This is a stupid question but is the smaller the number the bigger the wire.. /forums/images/graemlins/confused.gif /forums/images/graemlins/grin.gif

VA_Joe · Jan 14, 2006

As the other guys said - nothing wrong with AL wire as long as the contact antioxidant is used. The relative cost difference is a good reason to use it (500' spools of #12 copper have gone from $20 to $35 in the last year or so).

As Eddie said - with AL you will need to use a larger wire to get the same amperage. This can make it difficult to install the 100 amp breaker in the existing main panel which is already full of wires and - if it is an older breaker box - it will likely be narrower than a more modern one (making it more difficult to bend the wire).

Since this is for an out building - I would check to see if you can hook it up to the meter base (and yes - after the meter) vice the main panel. Depending on the size of your meter base - your power company may allow this (although if you tell them - they would likely want to charge a fee for coming out and doing the final hook up). The advantage of doing it this way is that it would make for a much neater installation and save two spaces in your house panel that could be used for other things.

Good luck and have fun.

Joe

Farwell · Jan 14, 2006

The smaller the number the bigger the wire until you hit #0 then the zeros are used. Example: #0 #00 #000. The more zeros the bigger the wire.
I use aluminum for out door wiring but never use it for any in wall wiring. Like Eddie said if you use it, either get devices designed for aluminum or use the anti corrosive coating stuff.
Farwell

gates · Jan 14, 2006

Buckcreek,
Be sure to allow for voltage drop at that distance. Assuming you are talking about 240volt single phase, #2 copper at 300 feet is ~ 5% voltage drop. I do not know what your state design requirements are. 3% is the typical design.

Ron

Keoke · Jan 14, 2006

Hi folks, aluminium wire "has a high flow rate under compression". Which means, as others have mentioned, that the tie point screws need to be checked from time to time.

chim · Jan 14, 2006

Copper cable is rarely used for residential services in this area. In the larger sizes, it is pretty trouble free. The biggest problems, as others have said, come from terminating it in lugs / screws that are intended for copper only.

There are a number of names for the compound that should be used when terminating it. Penetrox, CU/AL Aid, NoAlox, and others. Home Depot carries it. It's handy stuff to have. I use it on the terminals of vehicle batteries.............chim

drzmatt · Jan 14, 2006

Running #2 Al 300 feet for 100 amps will have way too much voltage drop. Use the link below to figure out your wire size.

http://www.electrician.com/vd_calculator.html

Buckcreek · Jan 14, 2006

i was wrong on the wire size . It was 2/0 service wire.

Farwell · Jan 14, 2006

Chim,
Thank your for you post. I have been looking for something to use on my battery posts other than that red goopy stuff. I never thought of the NoAlox that I have in my electrical supply box. I will give it a try.
Farwell

rswyan · Jan 14, 2006

I'm using 4/0 AL to run a 200A service out to my polebarn from the house .... the run is around 275'. I would think that you would be fine.

rambler · Jan 16, 2006

( i was wrong on the wire size . It was 2/0 service wire. )

As long as you understand you will be using 4/0 AL wire to be the equivelant of the 2/0 CU wire, and you follow the other things mentioned (AL terminals, AL grease is very important) then the AL service feeds are the normal way to go. AL is not much liked or accepted as wiring _inside_ a dwelling any more, too much arcing. Your dad may have reservations from that part of the isue. But AL is a good choice for the main feed these days.

--->Paul

rambler · Jan 16, 2006

( I'm using 4/0 AL to run a 200A service out to my polebarn from the house .... the run is around 275'. I would think that you would be fine. )

That's not real good, you will have a 4.6% voltage drop, or more that what is normally allowed. You should be several sizes larger. Will be pretty hard on electric motors this way.

Likely you are figuring on not using the full 200 amps ever, but just for the benefit of others - your 4/0 wire should be upgraded to 350kcmil size for a proper, 200 amp installation. Your 4/0 wire for 275 feet would suggest a 130 amp max draw.....

--->Paul

Inspector507 · Jan 16, 2006

rswyan,
Don't worry, we have been discussing your electric needs for some time and you are fine.
BTW there is no code requirements for voltage drop, only how the system should be designed for ''reasonable effeciency of operation". "Recommended" drop is 3% on BRANCH CIRCUITS and 5% on FEEDERS and BRANCH CIRCUITS . So unless you have a ton of wire run for each circuit in the barn, you'll probably be less than 5% anyway. Besides we took diversity into consideration as not everything imaginable will be running at any one time.

slowzuki · Jan 16, 2006

His polebarn should be ok with 5% voltage drop, its pretty near impossible to load a panel to 200 amps evenly. Especially in a workshop.

I'm running into the same problem, the electrician wants me to go up a gauge since my panel is 20 ft more than what 3% drop would be. I only really need a 100 amp panel but it seems stupid to spend extra to get a smaller panel.
Ken

rswyan · Jan 16, 2006

Thanks guys.

As the Inspector says I should be good .... the likelihood of me ever hitting even 130 amp draw is probably pretty slim. I am putting in a 200A panel in the barn (dropped off of a fused main disconnect switch in the house) mostly to be able wire multiple 220v/240v machines on individual dedicated circuits. Some of the stuff, like a Bridgeport and an engine lathe, I don't even have yet .... and probably won't for some time. /forums/images/graemlins/grin.gif Although, with the new washer and dryer that the wife got for Christmas, it looks like I will have a dedicated setup (as soon as I replace the motor in the dryer) for cleaning all my oily and greasy rags and clothes .... much to my wife's relief I'm sure /forums/images/graemlins/cool.gif

Like Ken mentions, the fact that the 200A panel was only a few dollars more than the 125A and 150A panels (and came with a a slew of breakers included) played into the decision a bit as well.

The panel in the barn will be located on the center of one side of the building and I'll be breaking up the branch circuits to keep the wire runs as short as possible.

Like the Inspector says not everything will be running at once .... it would be pretty rare for me to have more than a couple of things (besides some of the the lights) going at any given point.

I can also limit it by running lower amp fuses at the disconnect switch in the house ..... not that I would want to be popping them very often .... at around $50 a pop for a pair it would get pretty expensive real quick.

mudcat · Jan 16, 2006

If there is one thing I know, NEVER ARGUE WITH THE INSPECTOR. /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif I don't think you'll have a problem.

Keoke · Jan 16, 2006

Rswayn, I hear you on the sub-box rating compared to what amps you will actually use on the house to barn run dictating wire size. Bottom line, fuse wire from main panel to sub-panel to what your sub-panel feed wire can safely handle (100 to 150 amps) without overheating. This breaker size should be the same at both the main box take off and sub box main.
Going to a 200 amp breaker at house panel could have the unintended consequence of warming up the ground between your house and barn.

Correction: Rswayn, I messed up and missed the last sentence of your post on sizing down to smaller breakers to fit wire load.
Sorry about that. I will read slower next time!!!

take care,