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Old 03-12-2013, 09:17 AM   #1
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A/C Condenser Disconnect Box


Hi,

I am relocating my outdoor A/C Condenser and currently there are no electrical issues. I am only adding about 14 feet of distance to the overall length of #10 which should be just under 50' total from circuit breaker.
The current configuration (before move) the circuit breaker is dual pole 30 AMP with #10 gauge wire. This runs to an exist disconnect box just behind the condenser but what is strange is that this disconnect has 2 60 AMP fuses.

Does this sound logical?

I will not be using the existing equipment(disconnect) and will replace with new disconnect at the new location.

Should the new disconnect box have the same amperage as the circuit breaker or not fused at all? I live in south florida.

Thanks in advance.

John

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Old 03-12-2013, 10:45 AM   #2
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Check the nameplate on the condenser or consult the literature that you saved when it was installed. The condensing unit outside needs no fuses and is protected by a breaker in the panel only. A non-fused disconnect is what is normally used outside and is required.
What size breaker feeds the unit outside? If this breaker is 30 amp, then 30 amp protection is observed and the two 60 amp fuses mean nothing. (hurt nothing) If the breaker in the panel is 60 amp, the protection is redundant and requires no further action either.
The 60 amp fuses were most likely added as they may not have had a non-fusible disconnect when it was installed. (fused disconnect is not required) As long as the breaker in the panel is correct, any size fuse can be used outside.

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Old 03-12-2013, 10:56 AM   #3
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A/C Condenser Disconnect Box


Sure hope it's not 60 amp breaker with only #10 wire. The wire would melt before the fuse triped.
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Old 03-12-2013, 10:56 AM   #4
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Check the nameplate for minimum circuit ampacity and max OCPD. The what size OCPD is in the panel?
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Old 03-12-2013, 12:05 PM   #5
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Hi All,
Thanks for the information. This is indeed a 30AMP circuit breaker and 10 gauge wire. This condenser has a builtin inverter so this should handle the OCPD question. I would guess that if I install a 30AMP fuse in the disconnect then no harm no foul. I have been looking and I can not find a 30AMP non-Fusible disconnect.
Does this sound OK?

Thanks again
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Old 03-12-2013, 01:10 PM   #6
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There is no need to do anything with the fuses unless you just wish to do so. The 30 amp OCPD at the panel is protecting the circuit. The fusing means nothing. I suspect the previous owner just didn't buy a non fused disconnect.

In fact I would leave the larger fuses in place. One less place to have to look in the event of a future issue.
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Old 03-12-2013, 04:12 PM   #7
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Quote:
Originally Posted by joecaption View Post
Sure hope it's not 60 amp breaker with only #10 wire. The wire would melt before the fuse triped.
No it wouldn't, but lets not confuse the issue.
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Old 03-19-2013, 07:37 AM   #8
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Hi All,
I am moving my A/C condenser and it is going to be further away from the circuit panel and I need to know if the existing wire will be OK with the new distance.

Condenser Spec:
Volts-Cycles-Phases - 230-60-1
Total Amps - 18.0
Delay Fuse Max - 35
Min Circuit Ampacity - 22.9

The Condenser is currently connected to a 30AMP breaker with a #10 gauge wired and current run length is ~40 feet. The condenser will be moving to a location were the total length will be at ~58 feet.

I found this table in the condenser information
Supply Wire Length-Feet | Supply Circuit Ampacity
200ft | 150ft | 100ft | 50ft |
4 | 4 | 6 | 10 | 30

So does this read @100 feet start to use 6 gauge wire or between 100 ft and 50 ft use 10 gauge wire?


Am I with acceptable limits or do I need to make changes to something?

Thanks John

Last edited by whattodo; 03-19-2013 at 07:55 AM.
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Old 03-19-2013, 08:06 AM   #9
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You are fine with the #10 wire you have.
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Old 03-19-2013, 08:37 AM   #10
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Should be fine.
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Old 03-19-2013, 12:05 PM   #11
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Thanks everyone for the feedback but I have a followup on this. The label indicates the following...

Condenser Spec:
Volts-Cycles-Phases - 230-60-1
Total Amps - 18.0
Delay Fuse Max - 35
Min Circuit Ampacity - 22.9

I currently have in the new run a 30AMP disconnect with time-delayed 30AMP fuses and I was going to put in the max of 35AMP. It turns out the 35AMP and greater are bigger fuses that fit a 60AMP disconnect box.
Should I replace the 30AMP disconnect box (with 30AMP fuses) with the 60AMP disconnect box(with 35AMP fuses)? Any advantages going with doing the later? What is best?
This feed is a #10 gauge wire to a 30AMP breaker at a run of ~58 feet.

Thanks
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Old 03-19-2013, 12:21 PM   #12
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Have you had trouble with the fusing in the past? If not, don't re-invent your own wheel. Simply leave the 30 amp fuses in place.

Remember, you don't even need fuses if the breaker at the panel is correct for the wire size (which we earlier established is the case). So if you decide you just want to change the disconnect, buy a non-fused model (30 amp) and be done with it.
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Old 03-19-2013, 12:41 PM   #13
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35 amp is the max fuse, so like al said, if you have not had any problems, leave it like it is.
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Old 03-19-2013, 12:50 PM   #14
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Hi,
I have not had any issues with the current setup (60AMP disconnect with 60AMP Fuses) but I am replacing everything with new wire/boxes/conduit since I am moving the condenser. I have not had any issues but since I am replacing everything with new stuff I want to take this opportunity and make sure everything is correct and optimal.

Thanks
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Old 03-19-2013, 04:09 PM   #15
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Quote:
Originally Posted by whattodo View Post
Thanks everyone for the feedback but I have a followup on this. The label indicates the following...

Condenser Spec:
Volts-Cycles-Phases - 230-60-1
Total Amps - 18.0
Delay Fuse Max - 35
Min Circuit Ampacity - 22.9
Seems to me since your specs do not give you a MAX breaker, you must use a fusible disconnect. You can use #12 AWG wire if you wish....

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