Posted: 11/15/2009 8:07:22 AM EDT
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I originally put this in the survival forum but got no takers so hopefully more electricians will be here.
I've recently bought a 6kW 220V 30 amp generator. I've been looking for transfer switches and this one catches my eye. 
My problem is that I have two 50 amp breakers (1 for the stove and 1 for the dryer, each has a 20 amp and 30 amp tied together) then the rest of the breakers are 20 amp ones. Am I correct in assuming that the above transfer switch won't work well for me? This model has six 15 amp breakers and four 20 amp breakers. I didn't plan on running the electric range or dryer during an outage so it's kind of a moot point that those two 50 amp breakers for the house don't match the transfer panel. My bigger concern is all the 20 amp breakers for the house not matching the 15 amp breakers on the transfer switch. I could use 4 of the 20 amp breakers in that 10 circuit panel but then I'm wasting 6 circuits unless I tie two 15 amp breaker together to get three 30 amp breakers. That would give me 7 circuits from a 10 circuit transfer switch. Should I buy the transfer switch then change out the six 15 amp breakers and just make sure I keep the internal wiring straight? An interlock kit is pretty much out of the question since I'll have to hire someone to upgrade the load center; first to accommodate a generator breaker and second to accept an interlock device. |
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This forum is a fantastic resource for questions like yours.
http://zillerelectric.com/forums/index.php |
I'm wasting 6 circuits unless I tie two 15 amp breaker together to get three 30 amp breakers.
 It doesn't work that way (IF I understand you correctly)
"Tying two 15 amp CBs together ... in any recognizeable way ... does not give you a 30 amp breaker. Maybe I'm missing something, though. FWIW ... there is zero wrong with protecting a 20 amp circuit with a 15 amp breaker if you're not planning to load it up to 14 or 15 amps. Forgive me if you knew that. Stay safe |
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Quoted:
I'm wasting 6 circuits unless I tie two 15 amp breaker together to get three 30 amp breakers. It doesn't work that way (IF I understand you correctly)
"Tying two 15 amp CBs together ... in any recognizeable way ... does not give you a 30 amp breaker. Maybe I'm missing something, though. FWIW ... there is zero wrong with protecting a 20 amp circuit with a 15 amp breaker if you're not planning to load it up to 14 or 15 amps. Forgive me if you knew that. Stay safe That's what my question was about. Every breaker on my load center is 20 amp or greater. Six of the breakers in the transfer switch are 15 amp, four are 20 amp. So, say my bedroom outlets and lights are on circuit #12. Circuit #12 has a 20 amp breaker protecting it in the load center. You're saying it's OK for me to use switch "A" on the transfer switch, which has a 15 amp breaker, to allow me to run my bedroom lights from a generator? I want to use the 20 amp transfer switch breakers for other high priority areas like the furnace circuit , refrigerator and freezer circuit, etc. The max wattage I'd be using in the bedroom is ~200 watts for lights and a 1500 watt space heater. If I figure I'll use 1700 watts and divide watts by 120 volts I get 14.17 amps. Is that the right calculation to be doing? Is that cutting it too close? Thanks. |
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Quoted:
What exactly are the circuits that you want on the generator? how mant 15a & 20a circuits do you have? The transfer switch is a 10 circuit model. I don't plan to run my 40 amp range from the generator so I'll have all 10 circuits available. My home load center has a 20 amp and 30 amp tied together which runs the range. I have another 20+30 for the electric dryer. Again, I'm not wanting to power either from a generator. All of the remaining circuits for the home load center have 20 amp breakers. The transfer switch has four circuits with 20 amp breakers available. For those I was going to have: 1) Furnace with a 1/2 HP motor. 2) Fridge and freezer which are on the same single circuit. 3) Dining room outlet and lights + attached garage outlet, lights, and door motor all on the same circuit. 4) Kitchen lights and outlets. Kitchen has a 1500 watt microwave, coffee maker, and toaster in it all on the same circuit but not all run at the same time. For the six 15 amp breakers on the transfer switch I'd like to run bedroom lights and outlets. I have three bedroom upstairs and I don't care to power the downstairs bedrooms. I have a three 1500 watt electric heaters I'd like to be able to run in each bedroom in case the natural gas gets shut off. For one of the 15 amp breakers I'd like to run my natural gas fireplace blower. The fireplace blower is low wattage but it's on its own circuit in the house. So the circuits with 15 amp breakers for the transfer switch I'm thinking about are: 1) Kids bedroom #1 - has three 60 watt bulbs and nothing in the outlets. I want the potential to run a 1500 watt space heater. 2) Kids bedroom #2 - has three 60 watt bulbs and nothing in the outlets. I want the potential to run a 1500 watt space heater. 3) Master bedroom - has three 60 watt bulbs and phone chargers in the outlets. I want the potential to run a 1500 watt space heater. 4) Fireplace blower 5) Whatever lights the wife might want; probably the primary bathroom which would run fluorescent lights and the wife's blow dryer, and flat iron. 6) Whatever lights the wife might want; probably the family room lights and outlets so a 37" LCD TV and a fluorescent light. I haven't typed the above things broken down as far as load balancing but I've done the math and know how I want it arranged. |
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o.k. I'm trying to follow your first pot where you said that the dryer is on a 50a circuit. This can't be right, A dryer will only pull 20 somthing amps & allways is on a 30 amp circuit, Rarely, but I have seen them on a 20a circuit, but never on a 50a. Are you sure this breaker isn't a quad breaker, maybe a 30 for a dryer & the 20 for maybe a hot water tank or something else?
Either way it won't matter because you said that you don't want them on the generator anyways. So, with that being said it sounds like you have your load configured and should be good to go. Thier isn't anything that looks out of the ordinary with what you have going on. |
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Quoted:
I originally put this in the survival forum but got no takers so hopefully more electricians will be here. I've recently bought a 6kW 220V 30 amp generator. I've been looking for transfer switches and this one catches my eye. http://www.electricgeneratorsdirect.com/images/R30310B_200.jpg My problem is that I have two 50 amp breakers (1 for the stove and 1 for the dryer, each has a 20 amp and 30 amp tied together) then the rest of the breakers are 20 amp ones. Am I correct in assuming that the above transfer switch won't work well for me? This model has six 15 amp breakers and four 20 amp breakers. I didn't plan on running the electric range or dryer during an outage so it's kind of a moot point that those two 50 amp breakers for the house don't match the transfer panel. My bigger concern is all the 20 amp breakers for the house not matching the 15 amp breakers on the transfer switch. I could use 4 of the 20 amp breakers in that 10 circuit panel but then I'm wasting 6 circuits unless I tie two 15 amp breaker together to get three 30 amp breakers. That would give me 7 circuits from a 10 circuit transfer switch. Should I buy the transfer switch then change out the six 15 amp breakers and just make sure I keep the internal wiring straight? An interlock kit is pretty much out of the question since I'll have to hire someone to upgrade the load center; first to accommodate a generator breaker and second to accept an interlock device. You said that you have quote "My problem is that I have two 50 amp breakers (1 for the stove and 1 for the dryer, each has a 20 amp and 30 amp tied together) ". If you have have a 20 amp and a 30 amp breaker tied together to make 50 amps for your stove and dryer you have some major wiring problems that need to be fix BEFORE you add a transfer switch or any thing else to your electrical system. A dryer should be wired with 10 gauge wire and be hooked to a double pole 30 amp breaker. a stove should use 6 gauge wire and be hooked to a double pole 50 breaker. You cannot hook up a 20 and a 30 to get 50 if you house is wired this way call an electrican frist thing tomorrow to have this fix. Remember ELECTRICITY CAN AND WILL KILL YOU if you don't know what your doing and can BURN YOUR HOUSE DOWN if it is not wire correctly. You also made this comment "I could use 4 of the 20 amp breakers in that 10 circuit panel but then I'm wasting 6 circuits unless I tie two 15 amp breaker together to get three 30 amp breakers". Again you cannot repeat CANNOT tie two 15 amp breakers together to get 30 amps . As to your question yes you can put a circuit wired for 20 amps on a 15 amp breaker but you CANNOT put a circuit wired for 15 amps on a 20 amp breaker. |
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So, say my bedroom outlets and lights are on circuit #12. Circuit #12 has a 20 amp breaker protecting it in the load center. You're saying it's OK for me to use switch "A" on the transfer switch, which has a 15 amp breaker, to allow me to run my bedroom lights from a generator?
Yes. You would be using a breaker that would trip before the maximum rated current for the wiring. Generally, you can always "over-protect". What you must avoid is using a breaker (or any over-current device) that has a higher rating than the wiring, device, or equipment. I want to use the 20 amp transfer switch breakers for other high priority areas like the furnace circuit , refrigerator and freezer circuit, etc. Good idea, but see below. The max wattage I'd be using in the bedroom is ~200 watts for lights and a 1500 watt space heater. If I figure I'll use 1700 watts and divide watts by 120 volts I get 14.17 amps. Is that the right calculation to be doing? Is that cutting it too close? That is pushing a 15 amp breaker. FWIW, breakers are not supposed to be tripped a bunch of times ... they do weaken. The heater is the problem. If you plug it into a receptacle, I wouldn't put anything else on that circuit. If your frig worked on its own 15amp circuit you might consider leaving it on one. Google "Kill-A-Watt" ... a wattage meter. Amazon sells them. Very handy for what you're trying to do. Stay safe |