Question for the electricians

[MNBobcat]

I have a 30 amp fuseable disconnect box to install on the outside of my house for a ductless mini-split air-conditioner. It looks to me like the mini-split only requires a 20 amp, 220 circuit. I got to thinking that I don't think I should use a 30 amp fuse with wire rated for only 20 amps. So is it okay to put 20 amp fuses in the 30 amp box? I'm pretty sure it is but I hate to assume so I thought I would ask.

Please let me know if you're a licensed electrician or a DIYer if you reply.

Thanks!

 

[RNeumann]

The fuse should be at the panel and the "disconnect" is located by the condenser.

 

[RNeumann]

GE 6 Amp 24-Volt Non-Fuse Metallic AC Disconnect-TFN6RCP - The Home Depot

This is all you need. It's "rated" for 60amps but all it does is disconnect power at the unit for ease of service- which is code. As stated above- the fuse/breaker that protects the line is at the panel where the 20amp wire originates.

 

[Budweiser John]

The name plate on the AC unit will call out the full load amp draw.
Do not protect a 20 amp circuit with a 30 amp breaker.
If the disconnect you intend to use is the old style plug fuse type toss it and purchase the correct amperage breaker which if used out doors must be rated for exterior use and properly grounded.
B. John
Retired licensed builder

 

[RNeumann]

GE 6 Amp 24-Volt Non-Fuse Metallic AC Disconnect-TFN6RCP - The Home Depot

This is all you need. It's "rated" for 60amps but all it does is disconnect power at the unit for ease of service- which is code. As stated above- the fuse/breaker that protects the line is at the panel where the 20amp wire originates.

Edit- the "link" above is dropping the "0"s. It is 240v and 60a- not 24 and 6

 

[MNBobcat]

I already have the fuseable disconnect bought, which I got from an HVAC supply place, and I'm not going to return it.

 

[JPRambo]

Use the disconnect as is. It only going to be used as a service disconnect. Use a 20 amp breaker in/at the beginning of the circuit and you're good to go.
Electrician 35 years.

 

[jaxs]

I think you have a handle on what can and can't be done,all info so far is correct but I will say it different. Breaker/fuse "protect's"wire and devices DOWNSTREAM. Wire rated for more amps than fuse is exceptable and safe. Your mini-split will be protected and happy as long as there is correct amp fuse ANYWHERE in circuit. One common mistake is 30amp fuse feeding 10 guage wire that has been tapped with 12 guage wire then fused with 20amp breaker at END OF 12ga wire before power enter's appliance/outlet.
Retired building maintenance engineer.

 

[Passattdi]

Yep found that many places a wanna be electrician did work at my facility. All fixed now.

 

[buickanddeere]

I have a 30 amp fuseable disconnect box to install on the outside of my house for a ductless mini-split air-conditioner. It looks to me like the mini-split only requires a 20 amp, 220 circuit. I got to thinking that I don't think I should use a 30 amp fuse with wire rated for only 20 amps. So is it okay to put 20 amp fuses in the 30 amp box? I'm pretty sure it is but I hate to assume so I thought I would ask.

Please let me know if you're a licensed electrician or a DIYer if you reply.

Thanks!

The fuses or breaker in the supply panel are only for short circuit protection of the entire circuit and system supply. thermal protection of the conductors and thermal protection of the motor is provided by the motor thermal protection/overloads.
For example . It is Perfectly fine to use a 70amp breaker on #10 R90 wire rated for 35 amps load if supplying a motor with thermal protection. 70 amp breaker prevents nuisance tripping when the motor starts with the normal inrush current of 5 to 13 times greater than normal fuel load amps.