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Discussion Starter · #1 ·
Has anyone seen this? Working on an install and found two AC units sharing one Circuit Breaker but each unit has its own fused service disconnect.
The units sit side by side. The feed is coming to one service disconnect where it gets grouped with 2 8-3 wires. One going to the first unit and the other 8-3 goes to the service disconnect of the second unit where it leaves to the second unit. Each service disconnect is fused wit 40Amp fuses but the circuit breaker is a 50Amp breaker...
Does this look right?
 

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AlanDisaucis said:
Has anyone seen this? Working on an install and found two AC units sharing one Circuit Breaker but each unit has its own fused service disconnect. The units sit side by side. The feed is coming to one service disconnect where it gets grouped with 2 8-3 wires. One going to the first unit and the other 8-3 goes to the service disconnect of the second unit where it leaves to the second unit. Each service disconnect is fused wit 40Amp fuses but the circuit breaker is a 50Amp breaker... Does this look right?
What's the actual load on each unit?
 

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Discussion Starter · #3 ·
2 AC units one shared Cuircuit Breaker

They are both the same heat pumps rated at 40 Amps.
I forgot to mention. The main wire coming from the shared breaker is 6-3.
 

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AlanDisaucis said:
They are both the same heat pumps rated at 40 Amps. I forgot to mention. The main wire coming from the shared breaker is 6-3.
If both pull 40 amps and a 50 feeds them, I see trouble. If they are fed with romex you must use the 60 deg column to rate the wire.
 

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Discussion Starter · #5 ·
I know you can't pull a 6-3 then splice out 2 8-3s, they should all be 6-3.
Also Even if each heat pump has its own 40AMP fused service disconnect the wire as well as the circuit breaker in this scenario cannot/should not support both loads.
This setup has an electrical inspection sticker as approved!
 

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Discussion Starter · #9 ·
Nope, all NM-B. In fact they ran 6-3 and 8-3 to the heat pumps and cut the white conductors on each feed. They could've saved almost 50% on the cost of wires if they had used -2s.
Also these are 4 ton heat pumps on a 3500 sqft almost new construction (perhaps 3 years old) that already has issues... 4tons for each level! Talk about throwing money away...
I created the post to see if anyone has seen a single circuit breaker to two heat pumps...
I would've run 6-2 romex with a dedicated circuit to each fused at the service disconnect and each with a dedicated 40amp breaker at the panel.
 

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I would've run 6-2 romex with a dedicated circuit to each fused at the service disconnect and each with a dedicated 40amp breaker at the panel.
You most likely could get away with a 40 amp breaker, 10/2 and a non fused disco.
 

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Discussion Starter · #11 ·
2 AC units one shard Circuit Breaker

You might think you could but as per the manufacturer's specs the call is for the service disconnect to be fused.
 

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The entire question lies in the FLA of the units. If each unit draws 20 amps or so it may be compliant. The max overcurrent protective device does not mean anything in terms of load so yes this can be done but I agree you cannot tap the conductors as stated. There are rules for taps but it does not sound like they qualify
 

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I agree you cannot tap the conductors as stated. There are rules for taps but it does not sound like they qualify

Why don't you think they qualify?
 

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this thread is cletis
 

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Discussion Starter · #19 · (Edited)
Dennis, I take it you're not in HVAC, FLA on a heat pump is usually strictly the load on the fan. The FLA on the units in question is around 2.8A and the RLA is around 19A. I would prefer it if they would list the LRA but that's another issue. The units as I said are 4 ton each. The tag called (I say called because I turned down the job after they didn't accept my recommendations of pulling two independent circuits...) for an MCA of 26A and a maximum of 40Amps. To be honest with you, I decided to post here to see if there's a weird circus type situation where this setup has been applied. Would anyone share both loads on one breaker when it's just a matter of time this can cause a fire in a brand new over a million dollar house if these units seize up. Why not pull two separate circuits independent of each other! That's crazy! I thought it was odd that this install was approved by the township; I see you guys with thousands of posts giving the blessing to this nightmare... I already told you these are two 4 ton units you must expect a high LRA yet you're still saying it could be compliant! Like I said I told the customer I would not continue until you agree to run an additional circuit for the other heat pump and separate them. He refused. I said take care. Let some one else be blamed for your house fire.
 
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