ser 2-2-2-4 for 100 amp sub panel copper or aluminum

18 years ago

I know very often aluminum ser is used for feeders to sub panels but know aluminum wiring requires special wiring methods. When aluminum is used from a 100 amp breaker in a main panel to the lugs of a subpanel is there anything different about connecting it besides tightening to certain torques ect. If there is a special technique a description would be great and whether it is such a hassel if its better to go with copper, if it can even be found.

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electricalguru

17 years ago

If you are refering to Aluminum then you would not be able to use 2-2-2-4 for the 100A 'Remote Distribution Panel' because it would not comply to 310.15(B)(6) and the allowance.....you would need to use 310.16 and column 75 degrees because it is 100A panel and while some SE or SER can be rated for 90 degrees....guess what the terminals are probably NOT...so you would be only good for 90A and protect at that rating.

Now...copper....2-2-2-4 in copper...no problem as it is good for 115A.....but more expensive than AL....but you already know that...:)

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Comments (9)

petey_racer
18 years ago
Larger AL wiring is no problem. The issues with AL wiring is in the #14-#10 sizes.

You just need to use antioxidant past on the terminations. I coat the threads of lugs and breakers as well.
Follow the instructions on the paste container.

Like you said, I can't even get copper SEU & SER cable in my area.
normel
18 years ago
Spencer, make sure the AHJ in your jurisdiction will allow 2-2-2-4 Al to be used on a subpanel protected by a 100A breaker. Some will pass this, some will not. You may have to downsize the breaker to comply.
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mikie_gw
18 years ago
I live on salt water. #6 is or used to be the smallest alum size allowed. Most of the quality guys would try to clean off the alum connection of alum-oxidation thats on the new wire and use liberal amounts of no-alox.

Some make a point to go back a while after the jobs completion to re-tighten alum connections after it had a chance to cycle through some heat/cool expansion/contractions.

Really became a bit unusual to see burnt connections on larger wires.
petey_racer
18 years ago
When I lived on Long Island (obviously very salty air) I had never even seen aluminum cable, even SE.
I could only get SE in copper.

I moved upstate and can only get SE and URD in aluminum.
petey_racer
17 years ago
Paul, I have to respectfully disagree.
This can be a huge debate whether 310.15(B)(6) can be used for all feeders. MANY Areas DO allow it. Mine most certainly does.

It becomes semantics and word play as to what allows and what denies it. The words "main feeder" and "last overcurrent device" are two of the most debated phrases.

That said, I DO use #2al for 100 amp feeders (to sub-panels) ALL the time. This is absolutely legal and common in my area.
bus_driver
17 years ago
The TABLE 310.15(B(6) plus the Article 310.15(B)B(6) indicates that the #2AL is suitable for the feeders in this case. I try to go one size larger or use the CU. The retightening mentioned earlier is a very wise move.
itsunclebill
17 years ago
The area I work in has around 30 or so jurisdictions and all of them allow 2-2-2-4 Al to be a feeder for a sub panel rated at 100 AMPs. Never even knew it was an issue till I started hitting a few of these forums.
Keeping in mind that there might be young'uns reading I did delete a fairly long tirade about the subject.

UNK
HU-607168021
2 years ago
I am wanting to run wiring from my garage panel underground to another building. I was originally going to run 2 separate 20amp circuits. I was advised to run 3-2-2-4 aluminum wiring from a 50amp breaker to a sub panel in the second building. The second building is approximately 180ft from the garage panel. Is this a good idea, it looks like the aluminum wiring is too big for a 50amp breaker.