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Old 10-09-2008, 10:02 AM   #1
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Aluminum wire from main


I am putting a sub panel in and I am running a #3 aluminum wire. Somebody mentioned to me that I need to put what I believe is called
no-locks. Can someone fill me in on this. Also the sub panel is a 100 amp panel. What is the breaker that I need to use in the main panel. Is it a single pole 100 amp or a 2 pole 50 amp. I am not sure.
Thanks in advance for the help

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Old 10-09-2008, 10:12 AM   #2
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Aluminum wire from main


Quote:
Originally Posted by chatterbass View Post
I am putting a sub panel in and I am running a #3 aluminum wire. Somebody mentioned to me that I need to put what I believe is called
no-locks. Can someone fill me in on this. Also the sub panel is a 100 amp panel. What is the breaker that I need to use in the main panel. Is it a single pole 100 amp or a 2 pole 50 amp. I am not sure.
Thanks in advance for the help
Noalox is the brand name for an oxidizing inhibitor that electricians use on aluminum wire. Some will tell you that it isn't necessary and that there is no code requirement for it, but from my own experience, you should use it. I'm on the run so I can't detail the rest of what you should do as far as grounding and breaker size. Someone will fill you in.

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Old 10-09-2008, 10:58 AM   #3
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Aluminum wire from main


Rub it in good and squirt a little into the lug before you put the wire in.

A #3 AL cable is to small for a 100 amp breaker. Depending on what type of wire or cable you are using will determine the size of your breaker. This is for the breaker that FEEDS the sub panel. The feeder. Not the one in the sub.

You can use any size breaker you want in the sub. If the sub is in the same building (attached) you do not need a main in the sub panel. There are other issues and exceptions to look at. But we need to know what type of wire or cable you are using, separate building? In conduit or not? Let us know!

You can put the 100 amp breaker in the sub, regardless of the feeder size.

Last edited by J. V.; 10-09-2008 at 11:00 AM.
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Old 10-09-2008, 11:01 AM   #4
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Aluminum wire from main


You would use a double pole if this is a 120/240 volt subpanel, or a 240 volt.
for 120 volt only, use a single. 3 awg aluminum is too small though. How big is this sub panel? You don't need a means of disconnect at the sub location when the panel has a max of 6 cbs as long as it is in the same building as the main.

There are many other things that are required. Like ground rods, separation, etc.

Last edited by rgsgww; 10-09-2008 at 11:04 AM.
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Old 10-09-2008, 11:17 AM   #5
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Aluminum wire from main


Quote:
Originally Posted by chatterbass
Is it a single pole 100 amp or a 2 pole 50 amp. I am not sure.
Assuming your subpanel is 2 phase (which it probably is), and your main panel/service is 2 phase, then you would use a 2-pole 100 Amp breaker if you wanted to reach the full capacity of your panel. However...

Quote:
Originally Posted by chatterbass
I am running a #3 aluminum wire.
#3 CU wire would most likely be acceptable for 100A. #3 AL is undersized, so you would most likely have to go with #1 AL for the full 100A. You would probably have to use a 70A 2-pole breaker at the main panel with #3 AL.

I say "probably" and "most likely" because it depends on your answers to the following:

- How far is the main panel from the sub panel?

- What kind of #3 AL wire did you buy? Or is it a cable? (If you're not sure, then what's printed on the outside of the cable/wire?)

- Where are you running the feeder? (Underground, through conduit, stapled to framing, etc)

- If you're going through conduit, are the wires for your new feeder going to be in there with existing wires, and what is the size of the conduit?)

Do a search for "sub panel" on this forum too.. I haven't been on here long, but I know these issues with subs come up a lot.

Edit: I walked away in the middle of replying.. So my post crossed with rg and JV, didn't mean to repeat them.

Last edited by ScottR; 10-09-2008 at 11:19 AM. Reason: Inline above.
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Old 10-09-2008, 12:04 PM   #6
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Aluminum wire from main


Quote:
Originally Posted by J. V. View Post
Rub it in good and squirt a little into the lug before you put the wire in.

A #3 AL cable is to small for a 100 amp breaker. Depending on what type of wire or cable you are using will determine the size of your breaker. This is for the breaker that FEEDS the sub panel. The feeder. Not the one in the sub.

You can use any size breaker you want in the sub. If the sub is in the same building (attached) you do not need a main in the sub panel. There are other issues and exceptions to look at. But we need to know what type of wire or cable you are using, separate building? In conduit or not? Let us know!

You can put the 100 amp breaker in the sub, regardless of the feeder size.
sorry, its a number 2. I checked with my local inspector and he said the number 2 is fine.
the sub panel is 40' away and it is a single phase main lug panel.

Last edited by chatterbass; 10-09-2008 at 12:07 PM.
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Old 10-09-2008, 06:52 PM   #7
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Aluminum wire from main


2 awg should be fine. So this is a 120/240 volt panel right? Your going to need 4 wires (if your state says different, 4 wire is still safer in my opinion).
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Old 10-09-2008, 08:11 PM   #8
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Aluminum wire from main


Quote:
Originally Posted by chatterbass
it is a single phase main lug panel
I think rg misread.. You'll need 3 wire (hot/neut/ground), and a single pole breaker. (Unless I'm missing something?) In my last post I "ass"umed that you had a 2 phase panel.
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Old 10-09-2008, 08:15 PM   #9
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Aluminum wire from main


Scott, your terminology is off.

Pretty much all residential services are 120/240v SINGLE phase. There is NO "two-phase". There is single phase and three phase.
Panels are the same. Single phase; two busses. Three phase; three busses.

I know it is confusing but trust me.

Two hots and a neutral is single phase.

rgsgww is correct.
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Old 10-09-2008, 08:20 PM   #10
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Aluminum wire from main


Quote:
Originally Posted by Speedy Petey View Post
Scott, your terminology is off.

Pretty much all residential services are 120/240v SINGLE phase. There is NO "two-phase". There is single phase and three phase.
Panels are the same. Single phase; two busses. Three phase; three busses.

I know it is confusing but trust me.

Two hots and a neutral is single phase.

rgsgww is correct.
You were a little too nice.
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Old 10-09-2008, 08:25 PM   #11
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Aluminum wire from main


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Originally Posted by jerryh3 View Post
You were a little too nice.
I'll try harder next time.
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Old 10-09-2008, 08:34 PM   #12
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Aluminum wire from main


Quote:
Pretty much all residential services are 120/240v SINGLE phase. There is NO "two-phase". There is single phase and three phase.
Panels are the same. Single phase; two busses. Three phase; three busses.
I was the one guilty of mis-reading, b/c I read it as single lug.. (My face is a little red right now.. sorry rg..)

I'm clear on the terminology; I've heard 120/240 residential service referred to as "split phase", but I know that the 2 hots running into a (average) house are from a single utility phase, and the xformer is tapped so that phase is delivered to the home on 2 legs that are phased 180deg to each other. (Right?)

I've always hated the terminology though. I mean, (and I'm really wondering here, not trying to be difficult), from the customer's POV, is there any difference between split phase and 2-phases that are 180deg from each other?
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Old 10-09-2008, 08:35 PM   #13
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Aluminum wire from main


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You were a little too nice.
Don't see why he should be mean. If I'm wrong, I'm wrong..
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Old 10-09-2008, 08:49 PM   #14
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Aluminum wire from main


Quote:
Originally Posted by ScottR View Post
I was the one guilty of mis-reading, b/c I read it as single lug.. (My face is a little red right now.. sorry rg..)

I'm clear on the terminology; I've heard 120/240 residential service referred to as "split phase", but I know that the 2 hots running into a (average) house are from a single utility phase, and the xformer is tapped so that phase is delivered to the home on 2 legs that are phased 180deg to each other. (Right?)
Mostly right. Split phase is more properly applied to induction motors, but that's splitting hairs. It is a single phase at 240 V. Then it is center tapped to provide a neutral at half the voltage. The thing about phasing as applied here is kinda meaningless, because it's kind of obvious that they are 180 degrees from each other. When one side swings to peak positive, the other side is negative. Its like saying the poles of a battery are 180 degrees "out of phase" with each other.

Quote:
I've always hated the terminology though. I mean, (and I'm really wondering here, not trying to be difficult), from the customer's POV, is there any difference between split phase and 2-phases that are 180deg from each other?
Maybe not from a customer's POV, but 2 phase is an actual system. I should say was. 2 phase power was used in the early 1900s and stayed pretty common until the 20s or 30s. But 3 phase just proved to be better. I believe there may still be small pockets of 2 phase power distribution in some cities, but I'm not totally sure. At any rate, while you could call your home service two phase, it simply isn't. Hell for that matter, you could call it three phase, because the neutral is as "hot" as the other two legs, except it's grounded.
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Old 10-09-2008, 09:37 PM   #15
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Aluminum wire from main


Single phase and three phase are applied to the power BEFORE your transformer.
Check your power pole outside. If it only has one "hot" feed. it is single phase. If it has THREE feeds, it is three phase.

Look at the pole if there is any question.

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