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Old 01-04-2010, 08:42 PM   #31
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Quote:
Originally Posted by Kurt1968 View Post
What happened to my post? Now I'm really lost.
Just some discussion..............sorry...it happens

Are these newer breaker panels ?
I've run #3 wire for (2) 100a subs in my house - new panels rated for 75 degree column when chossing size of wire needed

Older panels may only be rated at 60c & then you would need #2

Is it hot up in the attic ?
Heat causes capacity to be derated, so a bigger wire would be needed

I guess we should also ask run distance

Actually we needed to know how big of a sub you wanted



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Old 01-04-2010, 08:43 PM   #32
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Originally Posted by Kurt1968 View Post
What happened to my post? This has nothing to do with what i asked.
Im sorry My appologies to you.

Your load for that panel would be just over 55A. So you could actually use 60 Amp wire with a 60 Amp breaker protecting your line to the subpanel,unless you wanted to have more room for expansion.

If you stick with 60 Amp you could use #4 SER copper cable or #3 SER alum. cable.
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Old 01-04-2010, 08:51 PM   #33
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Quote:
Originally Posted by codeone View Post
Im sorry My appologies to you.

Your load for that panel would be just over 55A. So you could actually use 60 Amp wire with a 60 Amp breaker protecting your line to the subpanel,unless you wanted to have more room for expansion.

If you stick with 60 Amp you could use #4 SER copper cable or #3 SER alum. cable.
Codeone .,

Sorry to bring up one question how you came up 55 amp I came up 42 amps if I used the standard sq footage count due the OP did not stated how big the area it will serve so that kinda leave me a good question to ask you.

Plus what more I do not know if he going run 15 amp or 20 amp genral circuit for receptales et lights as well.

Merci,Marc
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Old 01-04-2010, 08:54 PM   #34
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Quote:
Originally Posted by Kurt1968 View Post
What happened to my post? Now I'm really lost. My service is a 100 amps now. Can my subpanel be 100 amps? Like I said 1-750 watt heater and 1-1500 watt heater both 120v. And about 7 lights and 10-12 outlets. And what size wire from the main to the sub? I'm going to finish the attic for a little home theater. And rewire the rest of the up stairs also. I still have some knob and spool.
Again my appologies. Your load is approx 55A. So if you use a true 100A

For 100A using SER cable you would need a #1 cable for copper if you are using alumn it would need to be a 1/0.

You would need to run pipe to use the #3
You could also run #2 SER copper and install a 90A breaker to have room for your expansion.
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Old 01-04-2010, 09:04 PM   #35
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The 100 amp panel in the basement in brand new. Attic is not finished yet it is going to be though . Want to get this figured out first. The run is probably 40 to 45 feet maybe less. Was going to use the 100 amp so I could add more if needed.
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Old 01-04-2010, 09:04 PM   #36
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Quote:
Originally Posted by frenchelectrican View Post
Codeone .,

Sorry to bring up one question how you came up 55 amp I came up 42 amps if I used the standard sq footage count due the OP did not stated how big the area it will serve so that kinda leave me a good question to ask you.

Plus what more I do not know if he going run 15 amp or 20 amp genral circuit for receptales et lights as well.

Merci,Marc
Marc, I try to err on the side of safety. Used his largest heater at 125% then added 1.5a for each outlet either rec or lighting. Not necessarily the best way. Mel

Last edited by codeone; 01-04-2010 at 09:23 PM.
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Old 01-04-2010, 09:06 PM   #37
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Originally Posted by Kurt1968 View Post
What happened to my post? Now I'm really lost. My service is a 100 amps now. Can my subpanel be 100 amps? Like I said 1-750 watt heater and 1-1500 watt heater both 120v. And about 7 lights and 10-12 outlets. And what size wire from the main to the sub? I'm going to finish the attic for a little home theater. And rewire the rest of the up stairs also. I still have some knob and spool.
750w = 6.25a
1500w = 12.5a
7 lights x 60w/75w ...or ?? 7*60 = 3.5a

So you are up to 22.25a @ 120v without anything else

A LCD TV can use around 110-250w or more depending upoin size
A Plasma TV can use between 300-500w or MORE depending upon size
Evenly (perfectly) balanced a 60a 240v panel gives you 120a @ 120v

So you would have plenty of power with a 60a 240v panel

BUT, it all depends upon what other power requirements you will have
I used #6 wire hots & neutrals & a #8 ground for my 60a sub



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Old 01-04-2010, 09:07 PM   #38
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Originally Posted by Kurt1968 View Post
The 100 amp panel in the basement in brand new. Attic is not finished yet it is going to be though . Want to get this figured out first. The run is probably 40 to 45 feet maybe less. Was going to use the 100 amp so I could add more if needed.
How big is your main service? And is this panel in the basement already a sub panel? What is fed out of it already?
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Old 01-04-2010, 09:08 PM   #39
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So should i make it a 240 panel or make it a 120 panel? Main service is 100 amp. The whole house is feed out of it.
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Old 01-04-2010, 09:09 PM   #40
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So should i make it a 240 panel or make it a 120 panel? Main service is 100 amp.
Dont understand this question
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Old 01-04-2010, 09:10 PM   #41
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Scratch that question.
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Old 01-04-2010, 09:12 PM   #42
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You almost always setup a 240v panel
I have heard of people setting up a 120v panel for lower power use

I was merely trying to show you the total power available using both hots with only 120v loads

Sorry if we are confusing you



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Old 01-04-2010, 09:15 PM   #43
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Originally Posted by Kurt1968 View Post
Main service is 100 amp. The whole house is feed out of it.
We need alot more info now. What is the load already on this 100A main service? What kind of heat do you have in the main house? What is the square footage of the house? What kind of water heat do you have? Do you have a Washer and dryer? Is your Range gas or electric? Do you have air conditioning? Do you have a dish washer, disposal? ETC.?
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Old 01-04-2010, 09:28 PM   #44
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With the last question I know it complicated it more however we need to make sure you dont overload your existing service. You may depending on the answers to these questions.
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Old 01-04-2010, 10:27 PM   #45
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Some Inspectors do not like a 100a Main panel & a 100a sub off the Main panel

My last house I switched my electric stove over to gas to free up enough electric for a 30a 240v AC & a 50a 240v hot tub
I never tripped the Main breaker

With a 100a service the concern is that you may exceed the service & trip the breaker

So if you have other electric heat, AC, dryer, stove, etc your service may be close to being overloaded
Then the recomendation might be to install a 200a main panel & a 100a sub
Hate to tell you to do one thing & then you would be back after its finished & the Main is tripping



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