Can main breakers be replaced?

[cj7jeep81]

I'm wanting to install a sub panel in the 16x16 shed I built last spring. Panel is about 50-60 feet away from my house panel, so I'm just going to feed it off that. However, I just want to run a 30 amp panel to keep costs down (just want to wire up some lights and a few outlets).

I would like to have a panel with a main breaker, but so far haven't been able to find any smaller than 100 amps. I know I don't need that much, and don't want to spend that much on wire. So would it be possible to buy the 100amp panel, and then replace the main with a 30 amp breaker?

 

[walrus]

I'm wanting to install a sub panel in the 16x16 shed I built last spring. Panel is about 50-60 feet away from my house panel, so I'm just going to feed it off that. However, I just want to run a 30 amp panel to keep costs down (just want to wire up some lights and a few outlets).

I would like to have a panel with a main breaker, but so far haven't been able to find any smaller than 100 amps. I know I don't need that much, and don't want to spend that much on wire. So would it be possible to buy the 100amp panel, and then replace the main with a 30 amp breaker?

Why do you need a main breaker? Install a 30 amp breaker in your main panel and get a small 2 or 4 circuit panel and be done with it.

 

[chevyoneton]

Get a small mainbreaker-less 6 or 8 space panel and back-feed a regular 30 amp double pole breaker to supply the panel. Identify it as the main (black magic marker). As posted above you don't really need a main at the sub but if you desire one this would be the cheapest and easiest way to go.

 

[cj7jeep81]

i probably don't need one, but just like having them in case i need to quickly turn off power.

chevyoneton, not understanding what you mean with "back-feed a regular 30 amp double pole breaker to supply the panel". are you basically saying the same as walrus in that use the 30amp breaker in my house panel as the main for this one?

 

[Ezzie]

Nope - by "back feed" he means install a double 30A breaker in two of the regular branch circuit breaker slots in the sub panel and feed the incoming power from the house into the sub panel through that breaker rather than the main lugs.

Might be against code - I dunno - but it would work. The 30A double breaker would be your disconnect in the garage then.

Might be better to use a seperate 30A disconnect DPST box and feed power from the house through it to the subpanel.

 

[walrus]

i probably don't need one, but just like having them in case i need to quickly turn off power.

chevyoneton, not understanding what you mean with "back-feed a regular 30 amp double pole breaker to supply the panel". are you basically saying the same as walrus in that use the 30amp breaker in my house panel as the main for this one?

He is saying install a 30 amp 2 pole breaker in a small panel, bring your feeder(from the main panel) into the panel and attach the 2 hots to this breaker. It "back feeds" the buss.

 

[mrb]

when using a backfed breaker as the main in the panel, it has to be secured to the panel. Make sure the panel you are using can accomodate a holdhown kit. I know the 6/12 homeline does and the panel is like $16.

 

[mrb]

also, you need to (or should even if your area hasnt caught up to current codes) run a 4 wire feeder, 2 hots a neutral, and a ground, plus you will need a ground rod at the detached structure. In your sub panel, you will need a seperate grounding bar, and make sure the neutral bar isnt bonded to the panel.

 

[cj7jeep81]

ok, the back feeding makes sense now, but i really don't like the idea of it. i'd rather keep it straightforward. I do like the idea of feeding a disconnect first, then feeding the panel from that.

to make sure i have it straight, i could run a 30 amp breaker in my main panel to something like this
http://contractorservices.homedepot...2922&pid=3de628dd-134e-4b56-9e80-2458817bab3c
then just go from there to this?
http://contractorservices.homedepot...1951&pid=4d1a2e5d-8c52-4512-94ea-c49ac4d36f8a

i know i don't need 125, but i've already got that panel at home from an older project that didn't materialize.

 

[cj7jeep81]

one other question while i'm thinking about it. when my house was build, i had them install a 400amp meter base, and the electrician ran that to two seperate boxes. one has a 200amp breaker that is feeding the house, the other box has its own 200 amp breaker to feed my future shop. any problems with me putting the 30 amp breaker to feed my shed in the same panel with the 200 amp breaker to feed my shop? or should i just tie it into my house panel?

i have enough room inside the panel in the house, but that would add an extra 20-30 feet of wire to the equation.

 

[walrus]

one other question while i'm thinking about it. when my house was build, i had them install a 400amp meter base, and the electrician ran that to two seperate boxes. one has a 200amp breaker that is feeding the house, the other box has its own 200 amp breaker to feed my future shop. any problems with me putting the 30 amp breaker to feed my shed in the same panel with the 200 amp breaker to feed my shop? or should i just tie it into my house panel?

i have enough room inside the panel in the house, but that would add an extra 20-30 feet of wire to the equation.

Run it out of either one

 

[Gary S]

Since you want the main breaker only as a shutoff, just keep the 100A breaker. The wire feeding this panel must be fused properly at the main panel supplying the power. The size of the breaker at the sub panel doesn't really matter as it serves only as a shutoff.

 

[cj7jeep81]

thanks for all the replied. i'll probably just go with feeding a disconnect, and then feeding the panel i have. i'm much more used to using panels with main breakers thank panels with just the main lugs. how do these panels work? i know mine is rated for 125amps, and I've seen other ratings. without a main breaker, what happens if that 125 amps is exceeded? a main breaker would simply trip, what does a panel with main lugs do?

i have no intentions of overloading the panel, just curious as to how these work. thanks again for all the help!

 

[Charles (in GA)]

Backfeeding is common on small panels. As others have noted, you must use an approved hold down for the breaker in the panel that is used as a main. This is usually a clip or screw, but must be the proper, approved device for the panel. You simply mark that breaker as the MAIN.

The 200 amp disconnect boxes you mentioned probably do not have any provision for installing small breakers in them. If you have to run cable from the 200 amp disconnect, then the cable must be rated for the 200 amps. Using smaller cable will mean replacing the breaker with something sized for it.

Charles

 

[Terry Kennedy]

I would like to have a panel with a main breaker, but so far haven't been able to find any smaller than 100 amps. I know I don't need that much, and don't want to spend that much on wire. So would it be possible to buy the 100amp panel, and then replace the main with a 30 amp breaker?

The smallest Square D QO main breaker is the 50A QOM50VH at $93 list. I'd go with one of your other solutions.

 

[go4dave]

first,,, are you going to pull the standard household 240V to the garage "sub-panel"??? Next, the easy way,, and keeping with code. Put a 240V/30amp breaker in the main. Install a sub-panel in the garage. between the 30amp breaker run 6 gauge wire to the garage panel. You can put a disconnect inline,, before the subpanel,, that can shut down all power running through it. Either way, from the sub-panel run 14/3 for 15amp circuits,, or 12/3 for 20amp circuits.. Each circuit get a HOT, a GROUND, and every 2 circuits can share a NEUTRAL. This keeps everything to code. The only MAIN you have,, is the one,, were power comes from the power to your house,, or the pole to your house,, or the transformer to your house. Everything else is a sub-panel or disconnect. or both if used together.

 

[cj7jeep81]

Backfeeding is common on small panels. As others have noted, you must use an approved hold down for the breaker in the panel that is used as a main. This is usually a clip or screw, but must be the proper, approved device for the panel. You simply mark that breaker as the MAIN.

The 200 amp disconnect boxes you mentioned probably do not have any provision for installing small breakers in them. If you have to run cable from the 200 amp disconnect, then the cable must be rated for the 200 amps. Using smaller cable will mean replacing the breaker with something sized for it.

Charles

maybe i will consider backfeeding then. would save me $30 or $40 on a disconnect. i'll probably end up feeding it with 40amps, which should be way overkill for what I need. the 200 amp disconnect boxes just look to me like standard main lug panels, and take ge breakers that are available at home depot. i know they sell 200 amp and 100 amp breakers, but haven't looked for smaller. i'm pretty sure this breaker would work, but would have to double check.
http://contractorservices.homedepot...2291&pid=b2e264e0-cd51-4474-8188-d4a056e75ea3

I'll have to see which panel I have, but looks like this is what I would need to use a backfed breaker, correct?
http://contractorservices.homedepot...1997&pid=dc5057b6-b84a-4d95-84b5-f1e93994e112