Wiring for a new A/C condenser

[Junkman]

I am having a new A/C condenser, and the dealer asked if I was going to have the power from the panel to the outside unit installed by my electrician or did I want him to do it. It is a short distance, and I was thinking of doing it myself. He told me that the unit requires a 40 amp two pole breaker. The distance from the panel to the outside wall is about 10 feet, and it will be another 10 feet to the unit. I know that I will need a pullout disconnect box, and flexible liquid-tight conduit from the disconnect to the unit, along with some liquid-tight connectors. What I would like is some recommendations as to the size and type of wire to purchase, and what is a quality pullout disconnect box. He will do the connection inside the cabinet. thanks for the help, and if there is more information needed, please let me know. I am going with American Standard 3 ton 13 SEER units.

 

[Aceman]

You need the info from the nameplate to determine that.

MCA(minimum circuit ampacity) is self explanatory and is used to size the wire.

MOCP(maximum overcurrent protection), again self explanatory and is used to size the breaker/fuse size.

If it only lists fuses as the overcurrent protective device, you will need to install a fused AC disconnect. If it lists a breaker as an overcurrent device, I would purchase a nonfused AC disconnect.

You also have to remember you are required to have a 120v service receptacle within 25' of this unit. I typically buy the combination AC disconnect/GFCI recep enclosures, that way I'm only installing one exterior enclosure. If you already have a recep located within 25' than of course you don't have to worry about it.

https://www.amazon.com/dp/B0052MDMIS/?tag=atomicindus08-20

 

[mrobins297aaa]

I've never heard of that 120v service receptacle requirement for residential. At least not in the Detroit area. I know it's typical for roof mounted commercial equipment.
if so he'll have to run a neutral also.
better check that name plate 40 amp seems high for a 3 ton condenser

 

[Aceman]

I've never heard of that 120v service receptacle requirement for residential. At least not in the Detroit area. I know it's typical for roof mounted commercial equipment.

The code article is 210.63 for those with a code book. The receptacle is required and the code makes no distinction between whether it's residential, commercial, etc.

 

[Junkman]

I assume that you need to run a separate power cable for the receptacle? Can it be nonmetallic with ground sheathed cable or does it need to be encased in plastic conduit? I have seen that the disconnects are available in both 15 & 20 amp. Is there a particular reason for going for the higher amperage? There will be 2 condensers mounted side by side, and can one disconnect be with out the GFIC receptacle if the other disconnect has the GFIC receptacle, or is it a requirement to have both with the receptacles?

 

[mrobins297aaa]

I'm not saying your wrong, I'm sure it's in there. I'm not a electrician by trade but In 40 years on doing HVAC work, I've never ever seen it once on a residential AC condenser in the Detroit area.
I've been retired for 9 years, it's not something new is it?

 

[Norcal]

First required in the 1990 NEC, and in the '90 & '93 editions there was a exception for rooftop equipment on 1 & 2 family dwelling, that exception went away in 2002.


Note: It is prohibited to connect the required receptacle to the load side of the A/C disconnect.

 

[wyliesdiesels]

Its been required for a long time but I hardly ever see them...

 

[AntonLargiader]

Does through a window count as accessible and within 25'? We had new compressors installed a few years ago and there is no outdoor recep for them, but there's a window there with receps in that room. That's how you'd plug in equipment there.

 

[Norcal]

Does through a window count as accessible and within 25'? We had new compressors installed a few years ago and there is no outdoor recep for them, but there's a window there with receps in that room. That's how you'd plug in equipment there.

No, how would a service tech access it when someone is not home?

 

[rburke65]

With an inverter off the truck? Generator? There has to be lots of situations where there is no power available.

 

[Aceman]

I assume that you need to run a separate power cable for the receptacle?

Yes.

Can it be nonmetallic with ground sheathed cable or does it need to be encased in plastic conduit?

It can be NM cable assuming you're running it in a dry location where NM cable is allowed.

I have seen that the disconnects are available in both 15 & 20 amp. Is there a particular reason for going for the higher amperage?

No. The code only requires a 120v receptacle, it has no requirements regarding whether you use a 15 or 20 amp device.

There will be 2 condensers mounted side by side, and can one disconnect be with out the GFIC receptacle if the other disconnect has the GFIC receptacle, or is it a requirement to have both with the receptacles?

You are only required to have a 120v receptacle within 25' of HVAC equipment. It's perfectly acceptable to have one recep serving several pieces of HVAC equipment assuming they are all within 25' of the recep.

 

[AntonLargiader]

No, how would a service tech access it when someone is not home?

Who says anything needs to be accessible when I'm not home? J-boxes and panels need to be 'accessible', too, and they're inside. If the compressor is on my roof, it's not accessible when I'm away. If the recep is 10' away but inside a doorway, it's accessible but only when I'm home.

 

[Angelfire]

I'm not saying your wrong, I'm sure it's in there. I'm not a electrician by trade but In 40 years on doing HVAC work, I've never ever seen it once on a residential AC condenser in the Detroit area.
I've been retired for 9 years, it's not something new is it?

Been around for quite a while...I seem to remember seeing that in the 1999 code book but it may have even been earlier than that when it was introduced.

I just installed a condenser as part of my garage build and the inspector definitely verified I had a receptacle nearby (and accessible). I'm not in Detroit so it's possible it's not something they really look for there.
Cheers.

 

[Angelfire]

Who says anything needs to be accessible when I'm not home? J-boxes and panels need to be 'accessible', too, and they're inside. If the compressor is on my roof, it's not accessible when I'm away. If the recep is 10' away but inside a doorway, it's accessible but only when I'm home.

The inspector I suspect would make that determination as the code doesn't specifically say "outdoors" however, I don't think you'll win that argument. They require the disconnect outdoors essentially isolating all your indoor "accessible" panels/j-boxes/etc....and I would think they'd apply the same logic to the receptacle.

 

[alfredeneuman]

Does through a window count as accessible and within 25'?

NO

NEC 400.8 Uses Not Permitted. Unless specifically permitted in 400.7, flexible cords and cables shall not be used for the following:

(3) Where run through doorways, windows, or similar openings

 

[Junkman]

The existing service to the old condenser, they used the "Romex" pulled through the flexible liquid-tight conduit into the condenser. My thinking is that this was not proper, and that they should have used individual stranded wires from the disconnect to the condenser, inside of the flexible liquid-tight conduit. Am I correct on this, or is an acceptable method? If it isn't acceptable, is it OK to strip off the plastic covering, and use the solid wire that is inside of the Romex? Also, the original is 2 wires and a ground, and I was wondering if the code has changed on this. thanks

 

[brewchief]

Easiest way is to buy a premade A/C whip, it will have 3 thwn wires along with the liquid tite conduit and fittings all ready to go for less then you can buy everything separate, normally come in 4' or 6' lengths with 10 ga or 8 ga wire.

Sent from my XT1254 using Tapatalk

 

[zmaxmotorsports]

Who says anything needs to be accessible when I'm not home? J-boxes and panels need to be 'accessible', too, and they're inside. If the compressor is on my roof, it's not accessible when I'm away. If the recep is 10' away but inside a doorway, it's accessible but only when I'm home.

If you want somebody to work on your stuff it needs to be accessable,pretty hard to do much on your ac without access to the furnace/air handler part of system anyway.

 

[zmaxmotorsports]

Easiest way is to buy a premade A/C whip, it will have 3 thwn wires along with the liquid tite conduit and fittings all ready to go for less then you can buy everything separate, normally come in 4' or 6' lengths with 10 ga or 8 ga wire.

Sent from my XT1254 using Tapatalk

 

[ard]

...installed by my electrician or did I want him to do it.

Show of hands:

who thinks EITHER of these choices would result in a 120VAC outlet getting installed??

 

[wyliesdiesels]

The existing service to the old condenser, they used the "Romex" pulled through the flexible liquid-tight conduit into the condenser. My thinking is that this was not proper, and that they should have used individual stranded wires from the disconnect to the condenser, inside of the flexible liquid-tight conduit. Am I correct on this, or is an acceptable method? If it isn't acceptable, is it OK to strip off the plastic covering, and use the solid wire that is inside of the Romex? Also, the original is 2 wires and a ground, and I was wondering if the code has changed on this. thanks

Your thinking is correct.

NM-b is NOT rated for wet locations.

Sadly, i constantly see AC condensors wired with NM-b.

The proper method is liquid tight with 3 THWN conductors- can be solid or stranded but stranded is more flexible.

And as said above, u can buy premade AC whips.

No code change on number of wires as an ac condensor only needs 3- 2 hots and ground.

No u cannot strip the jacket off of NM-b and use the individual conductors because they are not labeled...

 

[wyliesdiesels]

Show of hands:

who thinks EITHER of these choices would result in a 120VAC outlet getting installed??

Probably neither judging by all the new AC condensors Ive seen installed WITHOUT a seevice receptacle...

 

[mobiledynamics]

Your thinking is correct.

NM-b is NOT rated for wet locations.

Sadly, i constantly see AC condensors wired with NM-b.

The proper method is liquid tight with 3 THWN conductors- can be solid or stranded but stranded is more flexible.

And as said above, u can buy premade AC whips.

No code change on number of wires as an ac condensor only needs 3- 2 hots and ground.

No u cannot strip the jacket off of NM-b and use the individual conductors because they are not labeled...

Small vibrations, but I was under the impression Stranded is always the defacto standard ?

 

[brewchief]

On a new A/C install where there was no A/C in the past we have the electrician add an outlet, when we do a replacement we only add one if there isn't one within reasonable distance. I talked to the inspector in our area and he told us he wasn't getting his tape measure out and then asked what kind of cheap *** contractor only has a 25' cord on his truck.

In the area I work in it was never enforced until 6-8 years ago, at that time they also began enforcing it for furnaces as well, we put a 4x4 box with a switch and GFCI receptacle on the side of every furnace we install now.

 

[AntonLargiader]

NO

NEC 400.8 Uses Not Permitted. Unless specifically permitted in 400.7, flexible cords and cables shall not be used for the following:

(3) Where run through doorways, windows, or similar openings

That answer makes sense to me. If extension cords are technically not permitted to be used through doorways and windows, then clearly an indoor recep of any kind does not meet the requirement.

Given that extension cords through windows and doorways are totally commonplace in the real world, it seems to me that the whole point of the HVAC recep requirement is to keep that from being necessary.

 

[Junkman]

Your thinking is correct.

NM-b is NOT rated for wet locations.

Sadly, i constantly see AC condensors wired with NM-b.

The proper method is liquid tight with 3 THWN conductors- can be solid or stranded but stranded is more flexible.

And as said above, u can buy premade AC whips.

No code change on number of wires as an ac condensor only needs 3- 2 hots and ground.

No u cannot strip the jacket off of NM-b and use the individual conductors because they are not labeled...

What size liquid tight would be required, and how do you connect the liquid tight to the NM-b cable inside of the cellar, or could I use the grey PVC on the outside to the disconnects?
I spoke to my electrician, and he told me that he was out straight, but he would come by and check my work and do the hook up inside the panel, before the A/C guy came to do the install. I want to do it correctly.
I purchased the pull disconnects (1 with a 20 amp GFIC, and one without the GFIC) and the 8 gauge whips today.

 

[mrobins297aaa]

Is this the 3 ton unit your getting? looks like a 30amp cir br

http://www.denverwinair.com/literat...onditioners/4A7A3/4A7A3036/4A7A3036B1000B.pdf

 

[Junkman]

The dealer hasn't given me the model number of the 2 units that he is installing. All that he said was that it required a 40 amp 220 breaker. I figure that if I set it up with the proper wiring for a 40 amp breaker, then if it is a smaller amperage breaker, there will be no loss, except for the possible extra cost of the size of the wire for 30 amps vs. the wire size for the 40 amp breaker.
Tonight I was thinking about using PVC piping, since it is easy to work with, and it would meet the requirement of being weather tight, and protect the wiring from damage. I was just wondering about pulling wire to the two units, can it be in the same conduit, or would I be better off using a smaller conduit, and having 2 runs, one to each disconnect? If I pull 3 #8 and 3 #12 (for the GFIC) through what size conduit would I need?

 

[mrobins297aaa]

I can't help with conduit size you need the electrical boys to help with that.
we always used the pre-wired whips like others have mentioned

 

[Norcal]

The dealer hasn't given me the model number of the 2 units that he is installing. All that he said was that it required a 40 amp 220 breaker. I figure that if I set it up with the proper wiring for a 40 amp breaker, then if it is a smaller amperage breaker, there will be no loss, except for the possible extra cost of the size of the wire for 30 amps vs. the wire size for the 40 amp breaker.
Tonight I was thinking about using PVC piping, since it is easy to work with, and it would meet the requirement of being weather tight, and protect the wiring from damage. I was just wondering about pulling wire to the two units, can it be in the same conduit, or would I be better off using a smaller conduit, and having 2 runs, one to each disconnect? If I pull 3 #8 and 3 #12 (for the GFIC) through what size conduit would I need?

The dealer needs to give you the information that Aceman mentioned in post number 2, that tells everything needed to wire the unit properly.

 

[ard]

I would run one PVC run to the units- just cleaner.

 

[Junkman]

Show of hands:

who thinks EITHER of these choices would result in a 120VAC outlet getting installed??

A/C contractor and the electrician both said that it was necessary.

What size conduit do I need for the 3 #8 wires, and the 3#12 wires going to the pull disconnect? I already have a 1 1/2" conduit from the cellar to the outside that isn't being used. Can I use this for the 6 #8 wires and the 3 #12 wires? Does the low voltage wires need to be in conduit also? I assume that they are not allowed in the same conduit as the #8 wires. thanks

 

[ard]

A/C contractor and the electrician both said that it was necessary.

Because you specifically asked, or it was in their proposals, unbidden by you?

Either way, the point is clear- many installs do not include an outlet....

What size conduit do I need for the 3 #8 wires, and the 3#12 wires going to the pull disconnect? I already have a 1 1/2" conduit from the cellar to the outside that isn't being used. Can I use this for the 6 #8 wires and the 3 #12 wires? Does the low voltage wires need to be in conduit also? I assume that they are not allowed in the same conduit as the #8 wires. thanks

The 1.5" is plenty. You could use 3/4". Wanna save the 1.5"? Depends on how easy a new run out of the basement would be...

http://conduitfillcalculator.com/



Low voltage does not 'require' conduit, but personally I run all LV in pvc. You can use PVC flex too. Just too easy for a lawn tool or aggressive weeder to yank on it. You CANNOT run it in the conduit with the 120/240V stuff

 

[Norcal]

Is 8 AWG necessary? With A/C equipment just because a 40A is called for does not mean * AWG is required, a smaller conductor may be just fine, example: a 3 ton packaged air conditioner calls for 18.3 A MCA, minimum circuit ampacity, and a 30A MOCP maximum over current protection means that it could be wired with 14 AWG on a 30A breaker, because the rules do allow it, but in no way is it allowed to use that for branch circuit wiring.

 

[wyliesdiesels]

A/C contractor and the electrician both said that it was necessary.

What size conduit do I need for the 3 #8 wires, and the 3#12 wires going to the pull disconnect? I already have a 1 1/2" conduit from the cellar to the outside that isn't being used. Can I use this for the 6 #8 wires and the 3 #12 wires? Does the low voltage wires need to be in conduit also? I assume that they are not allowed in the same conduit as the #8 wires. thanks

Im guessing that #8 is way overkill for your unit.

But there is no point in you or any of us making WAGs.

Get the needed info and then post it here. Otherwise youre wasting time...

 

[Junkman]

this is the unit...



http://redirect.viglink.com/?format...d1879ea4db6639656bbe1af129db4fc&libId=j3g...

 

[Norcal]

Minimum ampacity 18A, max overcurrent device, 30A, if THWN conductors are used then 14 AWG & a 30A circuit breaker is code compliant.

 

[wyliesdiesels]

what he said

 

[Junkman]

I don't know enough to disagree, and I would like to learn. I know that the breaker is designed to protect the wiring, and that a 20 amp GFIC requires a 12 gauge wire, so what I don't understand, is why the A/C unit that has a 30 amp breaker because of higher starting current draw, can use a 14 gauge stranded copper wire. I also understand that stranded wire can carry a larger amount of current than a solid wire, but I didn't think that it was that great of an amount, that you could reduce the wire size to that degree. I will accept that you folks understand this code requirement better than most, and I will follow your advise. Now, I have a couple of additional questions. The gauge of the feeder wire from the 30 amp breaker in the panel to the junction box where the stranded copper wire will be joined, is that 14 gauge nonmetallic sheathed wire, or does it need to be larger? Same question for the 20 amp GFIC line, what size stranded, and what about the feeder wire?