[pjdiaz]

Installing an A/C unit.. These r electrical specs...
Electrical
• Rated Voltage Outdoor: 230/208-60-1
• Rated Voltage Indoor: 230/208-60-1
• Rated Amperage: 11.0/12.0
• Minimum Circuit Ampacity (MCA): 16.8
• Maximum Overcurrent Protection (MOP): 25
The unit is going 18 feet away from panel and not in sight of electrical panel..
What size fuses on fusible dissconnect ?
What size wire ?
What size fuses ?

[mike 165278]

I would use #10 wire and fuse it at 25 amps, the recommended max over current rating. You could probably get away with #12 at 20 amps as well. Is this a single phase or 3 phase unit?

[pjdiaz]

I would use #10 wire and fuse it at 25 amps, the recommended max over current rating. You could probably get away with #12 at 20 amps as well. Is this a single phase or 3 phase unit?

A single phase... breaker size??

[mike 165278]

A single phase...breaker size????

What are you talking about? The A/C unit doesn't need to be fused at the disconnect, so you would just use a 25 or 20 breaker as per my previous comment. I imagine this is a residential installation. I've never seen a motor that is mutli tap multi phase. If this unit is pre-wired at 208v it won't work. So my question stands, single or 3 phase?

[pjdiaz]

Read Specs I sent u...
Single Phase... 230/208-60-1 = (voltage/voltage - hertz - phase)
And if don't use a fusible disconnect your not protecting the equipment and the person who has to service the equipment in the future. I was asking this question so that I could prove a point on how many unqualified people are out there doing electrical work... You need to study the NEC code book... Start by reading Article 100 . These are basic definitions you should know... Then brush up on 310.16 ( Conductor Ampacity ). Then read to Article 440 ( Air-Conditioning and Refrigeration Equipment ). Then read Article 430 (Motors)... Maybe you should use the NEC Handbook it has pictures. I bet you can't even tell me from what book the NEC is based from??

[pjdiaz]

Just because they sell fuseless disconnects it doesn't mean its right to use them...

[hkstroud]

I was asking this question so that I could prove a point on how many unqualified people are out there doing electrical work

I think you proved your point, but not the way you think.

[stanfortyman]

I would use #10 wire and fuse it at 25 amps, the recommended max over current rating. You could probably get away with #12 at 20 amps as well. Is this a single phase or 3 phase unit?

I hesitate to reply because this threads is nothing more than a troll thread.

Why would you use #10 for a 16A A/C load??

"Probably get away with #12 at 20 amps as well"? Do you know for sure, or are you guessing?
Code would allow #14 on a 25A breaker in this case. I'd use #12 just for the hell of it.


pjdiaz, sorry, I'm not playing you game any more.

[tkrussell]

To answer these specifc questions:

What size fuses on fusible dissconnect ?
What size wire ?
What size fuses ?

If the nameplate only states MOP, as this example provided does, then either fuses or an HACR rated circuit breaker is allowed.

If the nameplate states MOP fuses, then only fuses are allowed, usually satisfied by using fuses at the disconnecting means. No matter if a HACR rated circuit breaker is used at the beginning of the circuit.

If the nameplate states "HACR rated circuit breaker", then a breaker is allowed to be used at the beginning of the circuit, and no fuses required at the disconnecting means.

If the circuit breaker is not HACR rated, then the required disconnecting means at the unit shall be a 30 amp rated fusible disconnect and with 25 amp time delay fuses.

Assuming copper wire, this unit will require minimum #10 wire. #12 is not allowed as per NEC Section 240.4 (D) (5).

If only a HACR circuit breaker is used to protect branch circuit wiring and unit, it must be 25 Amp.

If fuses are used at the disconnect, because the feeder circuit breaker is not HACR rated, then the feeder circuit breaker can be 30 amp rated, with the 25 amp fuses at the unit.


Mike is incorrect with this statement:

"You could probably get away with #12 at 20 amps as well. Is this a single phase or 3 phase unit? "

Does this answer your questions?

Reading, understanding, and following the nameplate information is critical.