sub panel question

[neo1013]

I am going to be adding a 100 amp 6 space sub panel to my main panel. does anyone know how big the feed breaker needs to be? you know the breaker in the main panel that feeds the sub panel.

 

[kurtg]

100 amps? I have the same setup although an electrition isn't that expensive and I'd recommend using one.

My meter also has a 100 amp breaker so there are 3 100 amp breakers before the subpanel. Usually, the meter circuit breaker is the first to trip (which happened when a stove decided to short).

 

[Icefire]

Depend on how much you plan to load it.

6x15A = 90A
If you won't load it at full capacity, you can downgrade the breaker.

50A would be enought, give you 6000W of power.

 

[oldsaltman]

Re: sub panel question

<a href=showthread.php?s=&postid=9314305#post9314305 target=_blank>Originally posted</a> by neo1013
I am going to be adding a 100 amp 6 space sub panel to my main panel. does anyone know how big the feed breaker needs to be? you know the breaker in the main panel that feeds the sub panel.

FWIW I just did this too and I used 100a for mine.

 

[neo1013]

I just plan on running a few power tools off it, one at a time of course. right now the string of outlets i use for the tools are on with a freezer and blows halfway through a rip cut. i will be putting them on their own 20 amp circuit.

 

[Conesus_Kid]

I would just make sure you use the appropriate gauge wire from your feed to the subpanel.

http://www.xtronics.com/reference/wire_gauge-ampacity.htm

 

[neo1013]

I will be usine 6-3 wire

 

[Icefire]

50Amp max

 

[BeanAnimal]

<a href=showthread.php?s=&postid=9314617#post9314617 target=_blank>Originally posted</a> by Icefire
Depend on how much you plan to load it.

6x15A = 90A
If you won't load it at full capacity, you can downgrade the breaker.

50A would be enought, give you 6000W of power.

Why in the world would you downgrade the breaker?

If you have a 100A sub panel, then you feed it with a 100A breaker. There is not much cost difference between a double pole 100 and a double pole 50.

The breaker size is dictated by the feeder wire size, NOT the size of the branch circuit breakers in the sub panel. A 6 space panel can easily and legaly hold several hundred amps worth of breakers. One of my 100A subs has a double pole 50A breaker for the SPA and 12 other 15A-20A breakers.

 

[BeanAnimal]

<a href=showthread.php?s=&postid=9319629#post9319629 target=_blank>Originally posted</a> by neo1013
I will be usine 6-3 wire

If it is 6-3 Romex you can use 50A if you used #6 SEER cable you could bump it up to a 60A main. In any case I would just go ahead and get the 100A rated cable.

You will need to check with your local inspector. #4cu or #2al is usually the bare min for 100A. However 2-2-2 aluminum is actually only rated at 90A and some local codes or inspectors will not allow it on a 100A panel. Local codes may then requires #2cu or #1/0al (actually then rated for 125A).

You do understand that you MUST have 4 wires running to the panel. (2) HOT wires, (1) Neutral, (1) Ground. The sub panel must NOT allow the NEUTRAL and GROUND to be bonded.

If you are not 100% sure what you are getting into, please solicit the help of an informed friend or professional.

 

[Icefire]

Why would he feed a 100A sub panel with a 100A breaker if he will probably never use more than 30A.

Also, he can't use a 100A breaker on 6-3 cable, and it's not worth it to pass a #1/3 wire which cost a fortune compared to 6/3.

6/3 @ 220v with 50A per hot wire @ 110v, 11kW, enought for many power tools.

 

[BeanAnimal]

If I am going to go though the trouble of pulling wire to a 100A rated sub, then I am going to pull a 100A feeder to it. The wire is not that much more expensive, nor is the breaker.

We are just looking at it differently, thats all.

 

[Icefire]

Yeah, both would work, unless you have 100' between, 1/3 will cost a fortune.

My parents build a big garage years ago next to the home, 200A pannel in both house/Garage, the garage is feeded by a 50A double breaker.

It's enought for 2x 4800W heater, 8x 8' double strip fluo, some fan, etc.

There is just no use to feed the panel for 200A, as if you use it at max, the house breaker will trip since the house use 30A+