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Connecting portable generator to house. Why aren't transfer switches fused?

Connecting portable generator to house. Why aren't transfer switches fused?


  #1  
Old 09-17-14, 08:17 AM
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Connecting portable generator to house. Why aren't transfer switches fused?

I bought a portable generator, and wish to wire it into my house on a removable basis.

At present, I have a light meter that feeds a 100 amp switch that isolates the house from the outside world. This switch has 100 amp cartridge fuses in it.

That then feeds a trough, which feeds breaker panels for the house.

I plan on putting a DPDT, center off, manual transfer switch between the 100 amp switch and the trough. Diagrams suggest that you connect a generator socket to this transfer switch. The socket mounts on the outside of the house.

The generator is 7000 watts, so I would think that putting a 30 amp breaker between the socket and the trough would make sense. Otherwise, the only protection against a short in the generator or the socket is the 100 amp cartridge fuses in the house main switch. This seems like a bad idea.

Why don't they build a 30 amp breaker into the transfer switch to cover this? And since they don't, do I put a 30 breaker in between the generator and the trough? If so, where does it go? I'd assume that you put it as close to the trough as possible.

Thanks
 
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Old 09-17-14, 01:06 PM
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Welcome to the forums.

You don't need to install any breaker. Your generator should have its own protection breaker.

Your 100 amp cartridge fuses protect the meter source power..... nothing to do with the generator.
 
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Old 09-17-14, 06:12 PM
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I have a light meter that feeds a 100 amp switch that isolates the house from the outside world. This switch has 100 amp cartridge fuses in it.

That then feeds a trough, which feeds breaker panels for the house.

I plan on putting a DPDT, center off, manual transfer switch between the 100 amp switch and the trough.
I would think that putting a 30 amp breaker between the socket and the trough would make sense. Otherwise, the only protection against a short in the generator or the socket is the 100 amp cartridge fuses in the house main switch. This seems like a bad idea.
No, the power from the generator will never reach the 100 amp main fuses because they are ahead of the DPDT switch. When you throw the switch to get the generator feed to the trough/house, the 100A main fusible switch is out of the circuit.

Why don't they build a 30 amp breaker into the transfer switch to cover this?
You can usually buy a DPDT switch as either fusible or non-fusible. Some manufacturers may not have both.
 
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Old 09-17-14, 06:36 PM
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Don't most generators have fuses/breakers on them protecting each circuit?
 
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Old 09-17-14, 10:20 PM
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I have yet to see a portable generator that didn't have a main fuse or breaker...
 
 

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