Wiring a manual xfer switch


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Old 07-22-06, 06:11 PM
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Wiring a manual xfer switch

I am installing a manual transfer switch for a generator. The switch has 8 15-amp breakers and 2 20-amp breakers. Can the 15-amp transfer switch breakers be wired to circuits with 20-amp breakers from the house breaker box?
 
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Old 07-22-06, 06:18 PM
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That would depend on what the circuit are for. If the circuit can be a 15 amp circuit, then yews. If it must be a 20 amp circuit (small appliance circuit, bathroom circuit, laundry circuit) then no.

The proper solution is to replace the two 15 amp breakers in the transfer switch with 20 amp ones if you need 20 amp breakers.
 
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Old 07-22-06, 06:49 PM
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Originally Posted by racraft
That would depend on what the circuit are for. If the circuit can be a 15 amp circuit, then yews. If it must be a 20 amp circuit (small appliance circuit, bathroom circuit, laundry circuit) then no.

The proper solution is to replace the two 15 amp breakers in the transfer switch with 20 amp ones if you need 20 amp breakers.
Good question.
Even with a temporary situation as a power outage? Typicaly you would still have the GFCI protection. What if they were to power a bedroom? Just a practical look at it.
(Agreed they should remain 20A.)All wireing in any event must be #12 between ckts.. The GEN-Tran breakers, I don't know how available they are.

I have added a sub panel before with the critical loads on it, With a manual transfer between the main and sub so as to isolate the sub during an outage.
 
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Old 07-23-06, 03:15 AM
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FYI, I just found this in the manual for a different transfer switch: "The tranfer switch circuits for 15 amp breakers can be connected to branch circuits with either 15 or 20 amp breakers in the load center."

Also, according to the manuals for both transfer switches, GFCIs will be disabled when using generator power.
 
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Old 07-24-06, 05:21 PM
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If I understand how breakers work, they trip if too much current is going through. Therefore there should be no hazard in using a 15-amp since it will only trip lower, not higher, than the circuit is designed for.
 
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Old 07-24-06, 05:31 PM
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Yes, you are correct in you understanding of breakers on this point. What the other posters are saying is that there are several ciucuits in a home that are reqired to be on a 20 amp circuit and if you put them on a 15 amp circuit, this would be against code.

I understand their position but I would think there may be acceptance since this is an emergency situation and a short term solution.

Call you local electrical inspector and get his input. If he believes that the code section should be upheld regardless of the emergency situation, then that is your answer. If he says go for it, I, personally, see no problem with it. The worst you will have is breaker trips due to overloading of the breaker, but the conductor would be safe since it is rated for the 20 amps.
 
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Old 07-24-06, 05:49 PM
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Suobs,
Can I assume this is a transfer panel, and not a transfer switch? It is similar to a Gen-Tran or Reliance panel?

If so you CAN wire a 20 amp circuit to the 15 amp transfer switches. They completely bypass the 15 amp "gen" breakers when in "line" mode, so there is no code violation of limiting 20 amp branch circuits to 15a in normal use.
In an emergency situation I personally don't think it matters much that the circuit is limited to 15.
 
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Old 07-24-06, 06:03 PM
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Exactly, Speedy - it completely bypasses the house circuits, and yes it's an array of breaker switches like a Reliance (like I said, there are 10 breakers). It is called a "manual transfer switch" I guess because its function is to completely switch all wired circuits from the house panel to the generator panel. Once that's done, you are using the generator panel breakers. This is to prevent utility power from feeding into the generator or vice vice-versa if utility power comes on while the generator is operating.
 
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Old 08-07-06, 05:39 PM
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Originally Posted by Speedy Petey
Suobs,
Can I assume this is a transfer panel, and not a transfer switch? It is similar to a Gen-Tran or Reliance panel?

If so you CAN wire a 20 amp circuit to the 15 amp transfer switches. They completely bypass the 15 amp "gen" breakers when in "line" mode, so there is no code violation of limiting 20 amp branch circuits to 15a in normal use.
In an emergency situation I personally don't think it matters much that the circuit is limited to 15.
I couldn't agree more.

It's not like you would be doing something dangerous, just something that might not be perfectly inline with the code.

For what it's worth, I have a HAM radio in my emergency (SHTF) kit, but I don't have a license to use it. Don't tell anyone!
 
 

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