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Author Topic: what have you used for a main disconnect box?  (Read 1561 times)
John Z
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« on: September 14, 2008, 06:44:57 PM »

I am redoing my electric, putting in new circuit panel, changing from 30 amp to 50 amp, and cleaning up lots of wiring sins made by prior owners. What have you guys used for the main disconnect? What is in there now is a small box with two 30 amp breakers. Could that be used? Would i want to switch to two 50 amp breakers. Tell me what you decided on and why? TIA
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Jerry Liebler
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« Reply #1 on: September 14, 2008, 07:03:23 PM »

John,
     First, the function of the circuit breakers is to protect the wires, so the breaker rating must be less than the wires, to and from the breaker, can safely handle.  This means you'll not want to change from 30 amp breakers to 50 amp until you've verified that the wires into and out of that box are at least 6 AWG.
I have two boxes that could be called main breaker boxes which it is depends on the power source.  In both cases they are about 6" x 8" boxes that house a single 2 pole Square D breaker.  One houses a 50 amp 2 pole breaker and is located where my shore cord enters the bus in the left rear bay, it is the main when on shore power.  The other is in the compartment where my generator is located and is a 60 amp 2 pole breaker, it is after the transfer switch and ahead of the distribution panel, it serves as main on either inverter or generator power.  Since the 50 amp shore cord is supplied with 120/240 the breaker that protects it MUST be a 2 pole breaker, not 2 separate single pole units.
Regards
Jerry 4107 1120
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belfert
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« Reply #2 on: September 14, 2008, 07:09:00 PM »

If you are going to fifty amp you'll need 50 amp breakers for sure.  I used a regular 50 amp 220/240 volt double pole breaker in my load center.  I am assuming here you are doing the regular 50 amp service with two legs that should equal 240 volt across if the RV park is wired right.  If doing a single 50 amp leg ignore my post.

I don't have a seperate disconnect for my 110 volt.  I just feed right into my load center.  I couldn't find any load centers with a 50 amp main breaker so I just used a main lug load center and don't use the main lugs.  I feed the power through a regular 50 amp breaker.

I decided to go with standard household type load centers.  I know others have used marine load centers, but I found them to be very expensive and not as flexible.  Household load centers are not designed to be bouncing around down the road, but I have not heard of any problems.  The cover should hold the breakers in place.

My generator already has integrated breakers so I did not but a breaker at the transfer switch.  The main 50 amp breaker in the load center will protect the shore power cord.
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John Z
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« Reply #3 on: September 15, 2008, 05:14:30 AM »

Thanks guys! I am running new 6-3G cable between the main disconnect and the new circuit panel. And yes, i am doing the usual split of the 2 legs, i will not have any 240 circuits anywhere. The old system did not use a double pole breaker, so i am off to do my shopping for that this morning. I too am using household panels etc since they will be tucked away upstairs in the bus, except for the main disconnect. I do not plan on having a transfer switch, i will just plug my shore cord into the generator outlet and feed the rest of the system that way. My present inverter is only 1000 watts, and i control it manually. Thanks again for the input,,, back to work for me.
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« Reply #4 on: September 15, 2008, 07:56:35 AM »

John,

When I redid my electrical this summer I put in a main disconnect switch in the front bay on the incoming shore line, before it goes into the transfer switch and inverter. It wasn't necessary, as the power pole typically has a breaker, and/or the shore cable plug can be used to disconnect. I wanted one in the coach, though, as I intend to connect up a simple tester setup on the incoming power with a couple of the inexpensive 120v plug-in circuit testers, to give me a warm fuzzy about the incoming power before I send it on to my expensive transfer switch and inverter equipment.

I used a small Square D box which is rated for, I think, 60 amps, and comes without the breaker. Basically a panel with 2 slots in it. I installed a 50 amp 240 volt breaker in it on the two hot lines. I passed the neutral and ground on through.

My distribution panel also has a similar 50 amp 240V breaker in the number 1 and 2 positions which functions as the main for the panel.

I can show you this in a couple weeks. I'm planning on coming to your gathering in Moose Lake, unless something changes.

craig
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Craig Shepard
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John Z
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« Reply #5 on: September 16, 2008, 04:25:56 AM »

Craig, i wondered too about needing a disconnect there, but i did need a junction box to tie the shore cord to the 6-3g that runs to the circuit panel. As it turned out, i came home with what i think is the same box and breaker as you used. Are you going to have your tester working when you come up to Moose Lake?
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« Reply #6 on: September 16, 2008, 04:39:32 AM »

Craig, i wondered too about needing a disconnect there, but i did need a junction box to tie the shore cord to the 6-3g that runs to the circuit panel. As it turned out, i came home with what i think is the same box and breaker as you used. Are you going to have your tester working when you come up to Moose Lake?

Not sure. I haven't been able to get my motivation up and get to work on the bus. It's supposed to be nice all week, so maybe I'll get going on it. I need to pull the generator and put some other material under it, hook up the tester, and wire the gen starter to the bus batteries, plus about 400 other items.

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Craig Shepard
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John Z
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« Reply #7 on: September 16, 2008, 04:44:27 AM »

LOL, yep, it seems the list of chores never gets any shorter, does it?
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