A/C wiring manual says 14 awg & 20 amp breaker?

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  #1  
Old 06-16-11, 08:48 AM
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A/C wiring manual says 14 awg & 20 amp breaker?

Wiring a mini-split a/c and the manual says use a 14 awg & 20A breaker.

I ran about twenty feet of 14 awg exterior sheathed solid wire through conduit at the panel through the exterior wall and to the outside condenser unit.

...*then* I read "use a 20A breaker"

I thought I was going to use a 15A breaker.

Can I use a 20A breaker with this wiring?

This is the manual. See page #24 of the .pdf
http://us.lge.com/download/product/f...%29_011607.pdf

Can this unit operate on a 15A breaker?
See page #11 (first column unit LAN091CNP / LAU091CNP)
 
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Old 06-16-11, 09:06 AM
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If the instructions say number 14 wire with a 20 ampere circuit breaker then that is acceptable PROVIDING this is a circuit supplying ONLY the A/C unit. The full load amperage of the unit is less than 15 amperes but the start-up surge might trip a 15 ampere circuit breaker.

It is possible you could use a 15 ampere circuit breaker without any problems. You can always upsize the wire to number 12 if it makes you feel better but the number 14 IS the correct size.

Don't forget that you also need a convenience receptacle within 25 feet of the outside unit for servicing.
 
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Old 06-16-11, 09:14 AM
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Yes this will be a dedicated line.

There is another GFCI receptacle and line that runs elseware in the yard.

I used the same conduit that was inside the home, to run my new 14awg, and when I got to this receptacle box I branched off with another exterior conduit to the a/c unit.

Do I need a separate receptacle for this line?
 
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Old 06-16-11, 09:42 AM
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I'm confused by all your "lines" and where they start and end.

If you run additional wiring in an existing conduit you need to be aware of conduit fill requirements and also derating of multiple conductor requirements.

How many total wires are in the conduits, what type of insulation is on the wires and what sizes are the conduits?

The A/C unit does not require a receptacle but it does require a local disconnect at the outside (condensing) unit.
 
  #5  
Old 06-16-11, 10:09 AM
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Sorry if I didnt explain it well.

There was a 1" pvc electrical conduit running from the panel through the exterior wall to an exterior receptacle box. Inside that conduit was a previous 14awg exterior sheathed (gray) solid line. This line attached to a GFCI outlet in the box and then continued as a load wire through another 1" conduit to a shed.

I pulled a new 14awg exterior sheathed (gray) solid line though the same conduit running from the panel thhough the exterior wall to the exterior receptacle box.

Then I continued the pull through a new 1" conduit.

The right receptacle has the GFCI. The left side is empty.

Should I put a switch on the new line to the a/c as a "local disconnect" on the left side of the box?

The top conduit has two 14awg lines

 
  #6  
Old 06-16-11, 10:22 AM
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One problem fill wise and best practice wise is you are using cable instead of individual THWN wires. Second problem I think when you write "1" conduit" you are referring to the outside diameter not the trade size. From the picture I'd be surprised if it is more the 3/4". If your going to use cable you should really have only one in that small of a conduit.
 
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Old 06-16-11, 11:00 AM
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The incoming conduit looks to be 3/4 and the outgoing 1/2. The receptacle cover in't legal, neither.
 
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Old 06-16-11, 11:15 AM
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Originally Posted by Justin Smith View Post
The incoming conduit looks to be 3/4 and the outgoing 1/2. The receptacle cover in't legal, neither.
Agree. Didn't mention the outgoing because it probably has only one cable.
 
  #9  
Old 06-16-11, 04:24 PM
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Yep, my bad.
Home depot conduit and just relaying what the label said.
Incoming is 1" to box. Strait down from that box is also 1"
Branching to the left is 3/4"

Incoming to the box has two 14g wires & each of the lower conduits have one wire.

What type of cover should I use?
Do I need a switch to the compressor?
 
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Old 06-16-11, 04:58 PM
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each of the lower conduits have one wire.
You need a minimum of two wires to run anything. Do you mean cable.

Do I need a switch to the compressor?
Yes, unless you can see the breaker box from the compressor.

The right receptacle has the GFCI. The left side is empty.
That can be used for a switch. All grounds regardless of circuit must be tied together. Neutrals on separate circuits can not be interconnected.

What type of cover should I use?
An in-use cover.
 

Last edited by ray2047; 06-16-11 at 05:14 PM.
  #11  
Old 06-16-11, 06:43 PM
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The receptacle cover appears to be installed a while ago and may be grandfathered in.
 
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Old 06-16-11, 08:54 PM
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Wouldn't unhooking thw eires from the load of the gfi and reconnecting them to add the "T" count as modifying the circut?
 
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