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c66vet · Sep 21, 2012, 09:40 AM

I am installing a Mitsubishi Mini Split AC unit in my garage and have some AC wiring questions and clarification;

Electrical specifications;
Outdoor Unit
- power supply 208/230, Phase 1, 60 htz
- Max fuse size / circuit breaker - 20 AMP with time delay
- Min. circuit ampacity (A) - 17.1
- Fan Motor (F.L.A.) (A) - 0.93
- Compressor R.L.A. (A) - 12.9
L.R.A. (A) - 16.1
Indoor Unit
- power supply 208/230, Phase 1, 60 htz
- Min. circuit ampacity (A) - 1.0
- Fan Motor (F.L.A.) (A) - 0.76

I have a old circuit breaker panel, Federal Pacific, circuit breakers NA, NC or NAGF
- I have purchased a 20 AMP 2 pole breaker to be used Thick Series Double Pole 120/240 VAC, - replacement for Federal Pacific NA
- does this 20 AMP breaker have a time delay built in?

I plan to use 10 AWG wire from the double poled 20 amp breaker in the main circuit panel to a outside mounted AC 30 AMP Disconnect box.
- 55 ft run
I plan to use / run 3 separate AWG 10 wires in conduit;
- 2 10 AWG black wires (hot / hot) from the 2 pole circuit breaker to the 30 AMP outside mounted disconnect box
- 1 10 AWG green ground from the main circuit breaker panel to the outdoor disconnect box.

From the AC 30 AMP disconnect box to the AC condenser
- 6 ft run from the 30 AMP disconnect box to the AC condenser
- 10 AWG wire to be used, same as above in conduit
Are there any issues with the mis match between the 20 amp circuit breaker in the main AC panel and 30 amp disconnect?

The Mitsubishi mini split indoor unit is powered from the outdoor unit and requires a 3 pole disconnect. Items specified in the instructions;
- AWG 14/4 wire 600 V (Specified in the instructions, use double insulated copper wire with 600 V insulation)
- Leviton MS303-DS 3 pole disconnect switch

I want to mount the Leviton 3 pole disconnect switch at the inside entry door from the garage to the house.

- From the install location of the 3 pole disconnect switch to the outdoor unit is a 60 ft run of 14/4 wire.
- From the install location of the 3 pole disconnect switch to the indoor unit is a 50 ft run of 14/4 wire.
- 2 of the 14/4 AWG leads connected from the outdoor to the indoor unit are 208/230 V AC 1 phase, 3rd lead is used for thermostat, 4th is ground between indoor and outdoor unit. (I will use a separate dedicated ground wire between the outdoor and indoor unit. There is no ground connection on the MS303-DS 3 pole disconnect.
- will the 14/4 AWG wire support electrical requirements with a 110 / 120 ft run ? Between the indoor and outdoor units? Min. circuit ampacity (A) - 1.0, Fan Motor (F.L.A.) (A) - 0,76

- can I use the Leviton 3 pole disconnect as the on / off switch for the AC ? Instead of using the wireless remote control provided?
- could I use 4 single wires (AWG 14) run in conduit instead of 14/4 600 V double insulated copper wire i.e Honeywell TSW 14/4 as sold by mini split ac vendors at $1.65 per foot.
- or should I use a 12/4 AWG or 4 separate / single 12 AWG wire in conduit for the 120 ft run?
- how important is the double insulated copper wire with 600 V insulation?
- trying to keep costs down, price of copper wire is unbelievable.

Thanks
Bob

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