Over sizing the breaker question?

[kenwhite]

There is no such requirement or legal implication of responsibility. For example, every furnace in the US is installed with a plug in cord. No furnace in the US has any built in breaker or fused protection. Same can be said for table saws, chop saws, corded drills, vacuum pumps, etc. Every welder does state a max fuse or breaker for the device. That transfers all responsibility to the operator.

Like I said, every branch that has a socket has its breaker sized for the cable insulation type, cable run length, # of cables bundle togther, load duty cycle, and cable AWG size to protect the wiring. It is the manufacturers responsibility to fuse/breaker if they want to protect the end user equipment from excessive damage or fire hazards.

The breaker protects the wiring between the socket(s) and panel, it is not sized or designed to protect the equipment that is plugged into the socket.

Oh, and my furnace is hard wired into a fused disconnect and not plugged into a 120 V wall socket - this is per the manufacturers recommendation, so be careful when you use the word every...

Typically the minumum fuse/breaker size is recommended for proper operation so the circuit is not being interrupted often when trying to use the device.

[A/C Guy]

Like I said, every branch that has a socket has its breaker sized for the cable insulation type, cable run length, # of cables bundle togther, load duty cycle, and cable AWG size to protect the wiring. It is the manufacturers responsibility to fuse/breaker if they want to protect the end user equipment from excessive damage or fire hazards.

The breaker protects the wiring between the socket(s) and panel, it is not sized or designed to protect the equipment that is plugged into the socket.

Oh, and my furnace is hard wired into a fused disconnect and not plugged into a 120 V wall socket - this is per the manufacturers recommendation, so be careful when you use the word every...

Typically the minumum fuse/breaker size is recommended for proper operation so the circuit is not being interrupted often when trying to use the device.

I have installed every brand of furnace sold in the US. Not one requires hard wiring and a fused disconnect per the manufacturer. If your furnace is installed that way it is because of local codes.
Very few manufacturers list a minimum fuse. Most only list a maximum fuse or breaker size.

[kenwhite]

I have installed every brand of furnace sold in the US. Not one requires hard wiring and a fused disconnect per the manufacturer. If your furnace is installed that way it is because of local codes.
Very few manufacturers list a minimum fuse. Most only list a maximum fuse or breaker size.

That is funny because every HVAC forced hot air system I have seen is hardwired, and I did a quick search and found a few product manuals that require it too. In these manuals the manufacturer typically lists what type of safety disconnect and fuse/breaker is suggested too.

I have never seen a maximum fuse size listed for a plug in device, only a mimimum size for proper operation to avoid excessive tripping.

For hard wired devices, the recommended cable size, breaker/fuse, and disconnect is listed with the caveat that each installation is different and subject to local codes.