heat pump dryer

[pj333]

I want to install a heat pump dryer . It is 240 volts , the manual requires dbl 15 amp breakers , manual says

240V, 60Hz, 4.2A (208V, 60Hz, 4.0A) It says I should use use UL (Underwriters Laboratories) listed No.-10 AWG wire (copper wire only), or as required by local codes. If over 15 ft. (4.5 m), use UL-listed No.-8 AWG wire (copper wire only), or as required by local codes. Isn't 10 or 8 overkill for 15 amp breakers. A electrician told me it's only drawing 8 amps and I could actually use 14/3 but I want to use 12/3 to be safe. any thoughts on this. I'm not a electrician

 

[ericmark]

It depends on how the refrigeration device starts, does not matter if fridge, freezer, AC or any other heat pump, they can have an inverter drive, which means very little in rush, or a capacitor or other device to get it to start, the latter has too problems, one is a high in rush on start and the other is a limited start time.

The idea is the motor should hit full speed before the compressor has built up too much pressure. If the speed is not attained in time, the motor can stall, this means it will take overrated current and the over load will trip. Once the overload has cooled, it will retry, but the overload is not designed for repeated use, so unless it starts 99% of the time without it tripping, it will burn out.

So unless an inverter start, refrigeration devices are very susceptible to damage due to volt drop, here in the UK with a 230 volt 50 Hz supply the volt drop problem is not so high, but where the supply voltage is a lot lower, say 120 volts, the current is a lot higher, and so is the volt drop.

I have a program to work it out with 230 volts, but can't really work it out with American wire sizes, and 120 volts.

 

[FrodoOne]

I suggest that you re-post on the North American site of

https://www.diychatroom.com/forums/electrical.18/

 

[Ragnar_AT]

For all I know #14 AWG is the smallest wire size allowed for socket circuits by the NEC and used for all domestic 15 A circuits.

The manufacturer states a running current of slightly over 4 A, so I have a hard time seeing why you‘d need larger wires than a standard 15 A circuit unless the run was extremely long (which isn‘t something manufacturers usually consider, that‘s an installation design issue).

We‘re also talking 240 V (derived from a 120/240 V three-wire supply) so I can’t see any particular problems with voltage drop.