A/C Disconnect Question

Ridger

Member

Equipment
L3940 HST
Nov 26, 2014
142
5
18
North LA
I recently had some A/C repairs made on my home A/C unit (4 ton) and the repairman pointed out I did not have an A/C disconnect. It's an older home and I never thought about it. Anyway, I started looking at 60 amp A/C disconnects and installing it myself. I'm not an electrician, but it does not seem too involved. Turn the power off to the A/C off of course, splice the existing line, connect the two incoming wires to "Line" and the two outgoing wires to the A/C to "Load" with the ground connected. My question is regarding the low voltage wire. Does it need to be spliced and connected inside the A/C disconnect or do I leave it intact? Thanks for your time.
 

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85Hokie

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AS you probably understand - the disconnect is so the worker need NOT come into the house to cut the power.

AS for the low voltage wire - that should stay intact - that is part of the communication system that allows the inside "unit" to talk to the "outside" unit.

60 amp is right high.....what gauge wire is there?
Newer systems do not draw as much as the old systems.....and if you are placing a 60 amp on that system....there better be like 8 ga wire there or better!;)

Match the breaker to the wire;)
 

Stmar

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B2650HSDC
May 23, 2017
904
38
28
Buffalo, Wyoming
30 amp non fused disconnect should be fine for your unit. As stated above all it is used for is to disconnect line voltage when working on unit, there is no overload protection at this point, the overload protection is the breaker in the electrical panel. You should be able to pick up a 30 amp at most home improvement stores; ACE, Home Depot, Lowes, Minards, etc. Wiring is fairly simple; Line 1 Line 2 power wires, Load 1 Load 2 from the AC unit and the ground wires from each side will go into a common ground lug. Low voltage control wiring should be left alone, does not have anything to do with disconnect.
 

mickeyd

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bxray

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Bx25d
Dec 1, 2014
712
1
18
Cleveland, ohio
The 60a has heavy duty contacts.
Less chance of burnout.
I would use it.
It is a safety thing as well.
NEC requires a disconnect within 10***8217;.

There should be marking :
line ( from power source)
Load (the ac unit).

My dryer plug burned out so I put in a 60a plug and wire instead of a 30a.
The breaker is still 30a.

Ray
 

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Ridger

Member

Equipment
L3940 HST
Nov 26, 2014
142
5
18
North LA
Gentlemen, thanks for all your comments and help. I got the disconnect installed with no problems. The only thing I ran into was when I cut the power line to install the disconnect, I then needed a longer connection from the disconnect to the A/C unit. Not a problem, I got a longer connection at my hardware store, installed it and it seems to be working properly. The original power line from the house to the A/C unit is 10 gauge wire. My local hardware store had a 10 ft. length of 8 gauge wire that someone had cut but never picked up. He gave it to me for nothing and said it would work for what I am doing. So now I have 10 gauge wiring from the house to the disconnect and 8 gauge wiring from the disconnect to the A/C unit. It seems to be working fine. Are there any potential issues with this? As always, thanks for all your help.
 

yeehaw48

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kubota 6040 tractor, kubota utv 1100c
Apr 26, 2018
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ky
The weak link now in your system now is the 10 ga. wire. It is fine.because you have a breaker in the electrical panel hopefully 30 amp, protecting the weakest link. You are o.k.:)
 

Stmar

Active member

Equipment
B2650HSDC
May 23, 2017
904
38
28
Buffalo, Wyoming
10 ga. wire is right for a 30 amp breaker, which is the case for most AC units. The 8 ga. from disconnect to unit is fine, it is actually good up to 40 amps so should handle AC unit with no issues, will actually run cooler than 10 ga.