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Compressor wiring question.

Sticks McGee

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Trail Creek, IN
I got this compressor given to me. Tank has a pin hole on the bottom so I got another tank the same size. Once I swap the motor and pump over I have to run a 220 v circuit to it. I attached some pics of the motor plate. Curious to breaker and wire size. I will be using Romex ( I know that's not the actual name for that kind of wire).

Thanks in advance.
 

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wyliesdiesels

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Thats a funky rating.

Says 5HP but also SPL which is special and FLA is 15a which is about 3HP. 5HP would be in the mid 20s...

Id have to think about that one for a minute as the HP and FLA conflict with each other.

but if wiring for 3HP then you need #12 THHN in pipe or 10/2 NM-b aka Romex.
 

pattenp

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I'd just put it on a 30A circuit breaker using #10 Cu. Also hardwire it, no plug and cord. Use Romex for wire from panel to wall box, then an A/C flex whip with THHN wire from wall box to compressor.
 
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05wrangler

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you need to size off of 5hp. the 5hp SPL does mean special. But what it really means is this motor has the ability to develop 5hp. the FLA amps (15) is only to be used for your overloads. So here we go, let the arguments begin if they must, that's not what I here for-

(2014 NEC code)
step 1-
5 hp motor is rated for 28 amps. per the code

step 2
28x125%=35 amps....please move on to step 3 unless you question this step-------- if you want to have the convocation about being continuous vs non continuous lets have this convocation now. if you say its non then lets look at that code. 430.22E. now lets look at T430.22E. you tell me where you fall at with and please explain why you think it does. keep in mind the columns say " 5-minute RATED motor, 15 minute RATED motor, 30-60 minute RATED motor, and continuous RATED motor. again I'm not hear to argue I'm here to have an educated convocation about the code.

step 3
now we need to select wire.
35 amp at the 75 degree C column gets you #10s. I know your using "romex" so now we look at the 60 column you need #8 AWG.

step 4
if your breaker is like everyone else home breaker then it is sized like so, 28x250%=70 this is the LARGEST your breaker can if you don't have any problems starting. I would run a 60. if you have the paper work to this motor it might tell you a smaller size. if not then you default to this code)

step 5 overloads.
I'm assuming that motor has internal overloads. this is when you would use the FLA.


fun fact- your 230 volt motor is rated to run at either 240 OR 208. (I assume your running on 240 volts.) keep in mind if you run a 230 volt motor at 208 it wont last as long as it would in a 240 volt situation. 208 is right at the bottom of your 10% drop.

let talk ladies and gentlemen
 

Norcal

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you need to size off of 5hp. the 5hp SPL does mean special. But what it really means is this motor has the ability to develop 5hp. the FLA amps (15) is only to be used for your overloads. So here we go, let the arguments begin if they must, that's not what I here for-

(2014 NEC code)
step 1-
5 hp motor is rated for 28 amps. per the code

step 2
28x125%=35 amps....please move on to step 3 unless you question this step-------- if you want to have the convocation about being continuous vs non continuous lets have this convocation now. if you say its non then lets look at that code. 430.22E. now lets look at T430.22E. you tell me where you fall at with and please explain why you think it does. keep in mind the columns say " 5-minute RATED motor, 15 minute RATED motor, 30-60 minute RATED motor, and continuous RATED motor. again I'm not hear to argue I'm here to have an educated convocation about the code.

step 3
now we need to select wire.
35 amp at the 75 degree C column gets you #10s. I know your using "romex" so now we look at the 60 column you need #8 AWG.

step 4
if your breaker is like everyone else home breaker then it is sized like so, 28x250%=70 this is the LARGEST your breaker can if you don't have any problems starting. I would run a 60. if you have the paper work to this motor it might tell you a smaller size. if not then you default to this code)

step 5 overloads.
I'm assuming that motor has internal overloads. this is when you would use the FLA.


fun fact- your 230 volt motor is rated to run at either 240 OR 208. (I assume your running on 240 volts.) keep in mind if you run a 230 volt motor at 208 it wont last as long as it would in a 240 volt situation. 208 is right at the bottom of your 10% drop.

let talk ladies and gentlemen

A motor would need to be rated 208-230V although the current rated voltage is 200-230V, in order to be supplied at 208V, but 208V is rare in a residential situation.
 

05wrangler

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A motor would need to be rated 208-230V although the current rated voltage is 200-230V, in order to be supplied at 208V, but 208V is rare in a residential situation.

This would make since, but if it where then why would it be ok to us 240 but not 208? 240 is Is 4.3% over volt and 208 is 8% under. I have hooked up many of motors in a 208v system that where 230 volt. These motors where provided and spec per the job.:beer:
 
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Sticks McGee

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Trail Creek, IN
So if I run from my panel up into the attic then over to the compressor area then come thru the ceiling and down to a box can I remove this plug end and run this cable into the box? Romex would come into the box from the panel. Wire nut the connections in the box. Is this suitable?
 

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Gummi Bear

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Sunset, Texas
Sure, you can use a cord and receptacle

It is a disconnect





I went to the woods because I wished to live deliberately...

Henry David Thoreau
 
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Sticks McGee

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Trail Creek, IN
Question. If I run conduit I will use THHN. Wyliesdiesels said earlier to use #12. Is that correct? Do I use a 30 amp breaker with that? I'm thinking of using that instead of Romex. What's the best way to get the wire from the box (flush mounted in the wall) to outside the wall to use conduit? Also stranded or solid?

Thanks.
 

sberry

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There is probably good reason the code is what it is here, I have heard it. But more of these are wired 10 cable 30 breaker than not.
I actually feel better about that than 70.
I got a 3 and a 5 on 30, they don't trip. Got several buds run them on 30's for decades when we didn't know any better than to use 125 percent and put a 30 on a 10 wire when we were kids.
You woulda think we would have burned them all up?
I recall one from this forum, the guys dad had the "electrician" from work wire it up 18 years ago, 12 cable on a 7.5.
Probably sized the wire for 480.
 

pbon

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I have a 60 gallon CH 3.7hp 230V compressor rated at 15.7 amps. I wired a 30 amp 230v capable switch, light switch style, to turn it on and off sincebit is upstairs. I could use the breaker but I had read breakers are not made for every day use. I see no issue. My compressor drain is extended downstairs as well with a ball valve to discharge it outside.
 

wyliesdiesels

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I have a 60 gallon CH 3.7hp 230V compressor rated at 15.7 amps. I wired a 30 amp 230v capable switch, light switch style, to turn it on and off sincebit is upstairs. I could use the breaker but I had read breakers are not made for every day use. I see no issue. My compressor drain is extended downstairs as well with a ball valve to discharge it outside.

Unless the switch you used is HP rated for 3.7HP or more, it is not permissable to use that switch.
 
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Sticks McGee

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Trail Creek, IN
So. The question is: 12 ga THHN? Solid or stranded? 30a breaker? How best to get the wires from the box knockout (in the wall) to outside the drywall to run into conduit?

Thanks.
 
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