"Thin" DP circuit breaker for 5hp compressor?

[ScaldedDog]

My new Eaton 5HP 80g compressor arrives next week, and I have some questions as I plan the wiring. Chief among them are if the thin "single slot" circuit breakers are OK to use for a 5hp compressor? I'm thinking of using this one:

https://www.homedepot.com/p/GE-Q-Line-50-Amp-1-in-Double-Pole-Circuit-Breaker-THQP250/100356520

As you can see from the photos, I need something that will fit in the space I have, or I'll have to use the spot on the upper left where the existing compressor is serviced with a wide 40a breaker. (The existing one is a "5hp" Craftsman that's wired to a dryer outlet. That compressor will be going away, but I'd like to keep the outlet useful.)



Second, my run from the panel is very short - less than 4ft - so I'm planning to use 10g THHN. Solid, stranded, or does it matter?

I'm installing a disconnect, even though not required that close to the panel, for my own convenience. Thinking of using this:

https://www.homedepot.com/p/Square-...kW-Non-Fuse-AC-Disconnect-QO200TRCP/202353314

And wiring up the compressor with this whip:

https://www.homedepot.com/p/Southwi...lic-PVC-Conduit-Cable-Whip-55189307/203373118

Do any of the experts who help us out so much on this forum see any issues with my plan?

Thanks!

Mark

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[Bert_]

Move the bottom right single pole breaker up to the empty space. Put a 40A thqp on the bottom right.

#10 thhn is the perfect size for this. The whip can be #10 also

 

[sberry]

I would cut a slot in the bottom of the sheet metal and run the whip right in to the bottom of the panel and wire to a breaker. It dont get any better than that.

 

[nadogail]

I would cut a slot in the bottom of the sheet metal and run the whip right in to the bottom of the panel and wire to a breaker. It dont get any better than that.

What he said.

 

[sberry]

My Bud had a gig similar for 30 yrs. Comp was near the panel and he had a ball valve on it and turned it off when he left for a while. He didnt have the level of connected equipment we got but his didnt leak and hadnt ran for year after he died. If its working correctly is only on when you are using it. I am not sure the breaker started it under load since we first threw it. It might have been off once when I fixxed the motor a few years in and ran every day since.
My 3 has a starter and switch.

 

[sberry]

It was in a small garage, 28A 5 hp and while it wasnt super quiet it was plenty, short recovery running mechanic tools. 3/8 air ratchet and 1/2 impact. As I can recall bought it used for 400$. Changed the oil once about 10 yrs in when I did the motor repair, tightened the belts and not sure if they are still original? He might have replaced them. Other than the belt tension never needed any additional service in the next 20 yrs.

 

[sberry]

If I was gonna mess with a disconnect might likely stick on another 6 space panel and put it on a 60. Only slightly more work and cost than a ****** disconnect and could mount a 120 or 2 to it for power tools if a guy needed a little bit more? It would let him add a modern welder local.

 

[sberry]

I am a bit with function before form and some soesnt look too bad, might whip right out the bottom with a 6 and surface a 6 space or if I 3wanted to blow the budget they make an 8 in the same box just for this. The 6 is super common though and stocked everywhere. Whip your comp on to it. tailor the breaker there. I would do it if I thought I wanted a welder.
Cheap and in a hurry and wanted to work right now would whip it to that box.

 

[wyliesdiesels]

That breaker will not fit there in the empty space. its a single space for a single pole breaker.

notice how you have a single breaker at the bottom?

twist the bottom knockout and put the breaker there.

a 50a is probably overkill. a 30a or 40a should work.

 

[ScaldedDog]

That breaker will not fit there in the empty space. its a single space for a single pole breaker.

notice how you have a single breaker at the bottom?

twist the bottom knockout and put the breaker there.

a 50a is probably overkill. a 30a or 40a should work.

Thanks man. I wasn't clear originally, but that is what I was thinking, as those bottom locations are the only space I have that'll take a 1" breaker. So the 1" breakers are fine to use for this application?

Thanks all!!

Mark

 

[Bert_]

All you gotta do is move the single pole on the bottom right up to the empty space. Then you have room for the double pole thqp

 

[ScaldedDog]

I may move the one single pole, but I have room in either of the bottom knockout locations as is, no?

Mark

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[1Garageman]

Question, if he is going to go to 40 or 50 amps, how can he only use a 10 amp wire? Because it is a short distance?

 

[sparky 1971]

No. The breaker has to be on both legs in order to have 240 volt. It is going to have to be on the the top half of the bottom space and the bottom half of the space above (where the thin breaker Bert told you to move is located now). Look at the breaker below the empty slot. See how it's positioned in two spaces,? Copy that.

 

[alfredeneuman]

Question, if he is going to go to 40 or 50 amps, how can he only use a 10 amp wire? Because it is a short distance?

Circuits for motors and AC units don't follow the same ampacity rules as general circuits.
Don't you mean #10 wire instead of 10 amp wire?

 

[Bert_]

I may move the one single pole, but I have room in either of the bottom knockout locations as is, no?

Mark

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Almost, what you don't have is both phases. You can't get 240v in that spot.

 

[Bert_]

Question, if he is going to go to 40 or 50 amps, how can he only use a 10 amp wire? Because it is a short distance?

Because motors.

It only needs the big breaker for starting. Once running it draws less amps. The motor will have some sort of overload protection that will also protect the wire.

 

[ScaldedDog]

Thanks guys. Perhaps another dumb question:

Assuming I could shorten the conduit part of one of them, is there any reason I couln't use two of these whips:

https://www.homedepot.com/p/Southwi...lic-PVC-Conduit-Cable-Whip-55189407/202210500

One (that I'd have to shorten) to connect in the wall from the panel to the disconnect, and one to connect the disconnect to the compressor motor? The only reason I'd do it would be to not have so much wire and conduit left over, so it's not a big deal, either way. I wouldn't have thought of it, save for some suggestions above about using a single whip to connect the panel directly to the disconnect.

Mark

 

[sberry]

If you are going to wire it to this panel skip the disconnect. Be simple, run the whip from the comp to the panel, wire to the breaker. Code doesn't call for it.
It doesn't help to double do it. Only calls for it under certain circumstances.

 

[wyliesdiesels]

Actually a disconnect is required for a motor if it is not within 50’ of and not within sight of the breaker panel.

 

[brewchief]

I can't get the link to the whip to work but every one I have seen can be shortened, most come with a straight and a 90 fitting, sometimes it's worth picking up an extra fitting if those won't work out.

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[ScaldedDog]

The disconnect in this case is just for my convenience, to let me wire the part behind the wall, put the metal wall back together, then move the compressor to its final position and wire that part. Though not required, given that the compressor will be right beside the panel, it's cheap enough to do this way to make it worthwhile for me.

Mark

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[ScaldedDog]

I can't get the link to the whip to work but every one I have seen can be shortened, most come with a straight and a 90 fitting, sometimes it's worth picking up an extra fitting if those won't work out.

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Thanks. That's what I found when I looked at them, so I just picked up a couple.

Mark

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[1Garageman]

Circuits for motors and AC units don't follow the same ampacity rules as general circuits.
Don't you mean #10 wire instead of 10 amp wire?

Yes, I did, sorry. That amazes me that motors and AC units don't have the same "ampacity rules" as general circuits.

 

[wyliesdiesels]

Yes, I did, sorry. That amazes me that motors and AC units don't have the same "ampacity rules" as general circuits.

well you have to understand the reasoning behind it

The motor starter or integral overload protection, protects the wire and the motor from overload. The breaker cannot be used for overload protection because if it was sized for that, it may trip due to inrush currents. So the breaker only provides line and ground fault protection.

The wire is still protected from overload. just not with the breaker.

 

[sberry]

It may only be protected from calculated load, doesnt always have additional internal. May not even protect the line in all cases for thermal, only if it has a recept on it. Protects the line for fault.

 

[sberry]

The wire is still protected from overload. just not with the breaker.

Doubling down on that, we kind of come to the same point, a bit different route. Never know how someone understands it, I say it and it doesnt make any sense, Wylie says it then it might.

 

[Bert_]

Yes, I did, sorry. That amazes me that motors and AC units don't have the same "ampacity rules" as general circuits.

It does have the same ampacity rules as everything else. #12 NM is still good for 20A just like always. With compressors and motor we can put a bigger breaker on but the running current is still under the limit of the wire.

An A/C unit might pull 14A. #12 will run it fine. But on start up the compressor will pull 6-7 times it's running current. It would often trip a 20 breaker. So we are allowed to use a bigger breaker to allow for one or two seconds of start up current.

 

[sberry]

That is some good simple wording. The exception may be some welder wiring.

 

[ScaldedDog]

So, my compressor arrived today, with this sign on it:



Other than an abundance of caution, why else might the manufacturer require this?

I'll probably swap my #10 whips for #8 ones, but is that likely to cause any other problems? (e.g. Will #8 wire fit in the panel?)

Thanks,

Mark

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[wyliesdiesels]

Manufacturer is full of it.

#10 THWN is fine.

 

[Bert_]

That's hilarious. I wire 10hp single phase motors with #6 all the time. No need for that big of wire for 5 hp.

 

[ScaldedDog]

Any issue with me using #8 whips? The cost for me, other than the 1000th Home Depot trip of the year, is the same.

Mark

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[ScaldedDog]

The wiring inside the pressure switch is the same #10 THHN they are telling me not to use...

Mark

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[wyliesdiesels]

Now thats funny

 

[Norcal]

It does have the same ampacity rules as everything else. #12 NM is still good for 20A just like always. With compressors and motor we can put a bigger breaker on but the running current is still under the limit of the wire.

An A/C unit might pull 14A. #12 will run it fine. But on start up the compressor will pull 6-7 times it's running current. It would often trip a 20 breaker. So we are allowed to use a bigger breaker to allow for one or two seconds of start up current.

For motors and A/C’s it is allowed to use 14 AWG for 20A, 12 AWG for 25A, and 10 AWG for 25A. Just not allowed for branch circuits or NM cable.

 

[sberry]

yes thats the listing on ACond type things today which is where most hometime types might find it wired like that. There are a couple conditions that 12 can be used on 50 and although it is special wire lots of appliances have internal wire protected for fault with the 50 breaker. Common ****** buzzer welder, comes 12 cord. Listed and recommended circuit is 50A

 

[Bert_]

For motors and A/C’s it is allowed to use 14 AWG for 20A, 12 AWG for 25A, and 10 AWG for 25A. Just not allowed for branch circuits or NM cable.

If you're using thhn or similar wire in conduit then yes you can use the 75* ampacity. I thought it was easiest to keep it simple since many on this forum would be using NM.

 

[wyliesdiesels]

For motors and A/C’s it is allowed to use 14 AWG for 20A, 12 AWG for 25A, and 10 AWG for 35A. Just not allowed for branch circuits or NM cable.

fixed it for you

 

[ScaldedDog]

Thanks for your help, guys. All done, though I still have to plumb the air lines. I won't ask folks on the internet to approve the work, but if you see that I did anything dumb, let me know.

BTW, these Eaton Quiet Air compressors really are quiet, even out in the open in a metal building.

Mark

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