Sub-panel question

[rbahr]

Hi All,

I am running a 100amp sub-panel in my basement, 2-2-2-4 AL wire as the feed from the main to the sub-pane. The feed is fused at the main panel with just lugs at the sub-panel.

My main is a SquareD box QO (NOT the Homelite version).

The question is: I don't have any connection points in the Main box to hook up 2Ga wire - what do I use?

Thanks

Ray

 

[79mudbugg]

so how is the feed fused? with a breaker ? then the sub panel has main lugs

 

[mrb]

I am very confused. You say the feed is fused at the main panel. What feed, the feeder to the subpanel?

FYI you have to protect #2 AL at 90 amps, not 100. (unless the #2 AL is supplying the entire load of a dwelling unit)

You should have a 90 amp breaker installed in your main panel and your #2 AL goes into it. For the neutral if you dont have an open lug that will take #2 there is a lug that has a fork that goes into two holes on the neutral bar and allows you to land a larger wire. Make sure you get the proper one for whatever panel you have (QO?) dont use one from another mfgr or cobble something together.

 

[Aceman]

I am very confused. You say the feed is fused at the main panel. What feed, the feeder to the subpanel?

FYI you have to protect #2 AL at 90 amps, not 100. (unless the #2 AL is supplying the entire load of a dwelling unit)

You should have a 90 amp breaker installed in your main panel and your #2 AL goes into it. For the neutral if you dont have an open lug that will take #2 there is a lug that has a fork that goes into two holes on the neutral bar and allows you to land a larger wire. Make sure you get the proper one for whatever panel you have (QO?) dont use one from another mfgr or cobble something together.

He's inside, that most likely means SER cable. I don't have the book in front of me, but I believe it's rated 75 amps on the 60 degree column. That means 70 or 80 amp breaker, at the most.

I'd really like to know who's telling all these diy'ers to put 100 amp breakers on #2 aluminum...?

Are you guys reading it off a chart on the internet, is it something your grandpappy told you or what....?

 

[mrb]

He's inside, that most likely means SER cable. I don't have the book in front of me, but I believe it's rated 75 amps on the 60 degree column. That means 70 or 80 amp breaker, at the most.

I'd really like to know who's telling all these diy'ers to put 100 amp breakers on #2 aluminum...?

Are you guys reading it off a chart on the internet, is it something your grandpappy told you or what....?

ah good point.

i wonder that too. I think they look at charts on the internet, find one that has the number they want and call it ok.

 

[walrus]

In Maine you can protect #2 SER at 90 amps, they never adopted that code. There are millions of installs with #2 SE or SER at 90 amps with no issues so why was the code changed? for someone to make make money with no basis in safety

 

[ForceFed70]

Your 2 hot wires go into the breaker for the sub-panel.

The neutral and ground are likely your problem. They sell larger neutral lugs that connect to the existing neutral "Bar". For the ground, you can buy a lug that you screw to the panel enclosure using a sheet metal screw.

 

[mrb]

Your 2 hot wires go into the breaker for the sub-panel.

The neutral and ground are likely your problem. They sell larger neutral lugs that connect to the existing neutral "Bar". For the ground, you can buy a lug that you screw to the panel enclosure using a sheet metal screw.

BAD advice. you absolutely cannot (in the USA at least) use a sheetmetal screw for a ground connection.

 

[ForceFed70]

BAD advice. you absolutely cannot (in the USA at least) use a sheetmetal screw for a ground connection.

Weird. My electrical inspector was the one who told me to use a "self-tapping screw" to install the ground lug.

 

[Aceman]

Weird. My electrical inspector was the one who told me to use a "self-tapping screw" to install the ground lug.

Sweet baby jesus....your inspector has NO CLUE!! Your only allowed to use screws with machine threads, not the typical coarse thread sheet metal screws. I have some special 12-24 self drilling machine screws I use just for this...

Greenlee sells a combination drill/tap kit that works wonders for tapping machine screw holes.

 

[mrb]

Sweet baby jesus....your inspector has NO CLUE!! Your only allowed to use screws with machine threads, not the typical coarse thread sheet metal screws. I have some special 12-24 self drilling machine screws I use just for this...

Greenlee sells a combination drill/tap kit that works wonders for tapping machine screw holes.

should also mention you cant always tap a hole -there has to be X number of threads engaged. Most panels have an embossed (dont know if thats the right term) hole where ground screws go which gives them more thread engagement.

 

[Charles (in GA)]

The "self threading screw" he is probably talking about is a MACHINE screw that has a V shaped cut along the side of it, that allows it to cut threads as it goes. This saves having to first tap the hole.

I think the code says you have to have two full threads engaged.

Charles

 

[rbahr]

Hi All,

Wow - thanks for the replies. OK to clarify:

79mudbugg & mrb: Yep fused in the main panel, lugs in the SUB - I was trying to find the part number or at least the real name for "lug that has a fork that goes into two holes on the neutral bar and allows you to land a larger wire."

Aceman & mrb: Yep did some research and found this number - actually I looked up the 100A breaker and saw that this is what several folks recommended. I also asked at the 'big box store' who sold me the wire.

If 60 or 70 amp is the correct size breaker than just tell me - I am looking for advice from folks who know what they are doing, not "they look at charts on the internet, find one that has the number they want and call it ok."

Thanks again

Ray

 

[cj7jeep81]

He's inside, that most likely means SER cable. I don't have the book in front of me, but I believe it's rated 75 amps on the 60 degree column. That means 70 or 80 amp breaker, at the most.

I'd really like to know who's telling all these diy'ers to put 100 amp breakers on #2 aluminum...?

Are you guys reading it off a chart on the internet, is it something your grandpappy told you or what....?

I had to get a new sump pump the other day, and was getting a price on wire to run to my shed. Went to a plumbing/electrical supply store, and the guy there said I'd be able to run 60 amps on 6 gauge aluminum wire to my shed, as long as it wasn't too far. So I wouldn't blame it all on the internet