Hooking up 220 compressor

[cplnorton]

Guys forgive me. I'm great at 110. I **** at 220. I have never really messed around with it much.

But anyways, I bought a harbor freight compressor. Looks like 5HP, 22Amp peak.

I have an existing 220 in my Garage that I would like to hook it too. I think the one in my Garage is more than enough to support it.

It looks like the box in the Garage is on a 50amp breaker. The wire looks heavy enough. I think I'm good on just buying a 50amp range cord and installing it on my compressor and plugging it in. But I want a second opinion by you guys that know what you are doing.

But here is my plug in, in my Garage. It's on a 50 amp breaker. It has a cover I just removed it.

My compressor is 5HP, 22Amp. So I think I can just buy a 50 amp cord like this and wire it to my compressor correct?

 

[pattenp]

If it's a true 5HP motor on the compressor then it should be hardwired. No plug because the plug does not have the proper HP rating, most likely plug only has 3HP rating. Does the motor data plate actually show 5HP? Not the label on the tank.

 

[casmurbax]

pattenp beat me to it

not seeing any pictures
If it is a true 5hp motor it will need to be hard wired.
See if you can get a picture of the motor plate and post that as well.

 

[cplnorton]

Here is the info that I see on the compressor. thanks guys for responding!

 

[yatg]

But here is my plug in, in my Garage. It's on a 50 amp breaker. It has a cover I just removed it.

What size cable is feeding this?
Maybe a picture of the receptacle itself.

waiting for for voltage correction 3 ... 2 ... 1 ...

 

[cplnorton]

What size cable is feeding this?
Maybe a picture of the receptacle itself.

waiting for for voltage correction 3 ... 2 ... 1 ...

The receptacle? You mean like this?

 

[pattenp]

You are making comments like there something to see but there no pictures. ???

 

[The Cobbler]

for imgur pictures to show up on here, you need to remove the "S" from the "HTTPS" in your links

 

[95vette]

The receptacle looks like it will handle it, but look at the plug that goes into it and see if it say it will handle five horsepower.

 

[wyliesdiesels]

OP your pictures arent loading

 

[wyliesdiesels]

The receptacle looks like it will handle it, but look at the plug that goes into it and see if it say it will handle five horsepower.

There isnt a NEMA 6-50 receptacle that is rated for 5HP so thats a no go.

 

[BD1]

There isnt a NEMA 6-50 receptacle that is rated for 5HP so thats a no go.

Huh?? His 5 HP motor is rated at 22 amps.
What does 5 horse have to do with it ??
As long as his wire size is rated to match breaker, his 5 HP motor wouldn't care.




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[wyliesdiesels]

Huh?? His 5 HP motor is rated at 22 amps.
What does 5 horse have to do with it ??
As long as his wire size is rated to match breaker, his 5 HP motor wouldn't care.




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Totally Incorrect.

With motor circuits, devices are required to be rated for same or higher HP as what the motor is rated at.

An example is Motor starters which are sized based on HP NOT amps.

The same goes for a receptacle. The receptacle is required to be rated for the same or higher HP as the motor.

Also, the wires for motor circuits are sized based on HP and FLC tables NOT breaker size.

 

[BD1]

Totally Incorrect.

With motor circuits, devices are required to be rated for same or higher HP as what the motor is rated at.

An example is Motor starters which are sized based on HP NOT amps.

The same goes for a receptacle. The receptacle is required to be rated for the same or higher HP as the motor.

Also, the wires for motor circuits are sized based on HP and FLC tables NOT breaker size.

HF states 5 HP motor needs to be connected to at least 25 amp source.
Add a box and direct wire.
Motor data plate has FLA which would be followed . Wire size is based on amps and breaker required.
I can't see anyone looking at FLC tables when motor data is on motor.


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[bubinga]

for imgur pictures to show up on here, you need to remove the "S" from the "HTTPS" in your links

Why not just host them here?

 

[u2slow]

HF states 5 HP motor needs to be connected to at least 25 amp source.
Add a box and direct wire.
Motor data plate has FLA which would be followed . Wire size is based on amps and breaker required.
I can't see anyone looking at FLC tables when motor data is on motor.

An electrician pulling a permit and putting his ticket on the line, would check the tables. Its the liability game.

It should do fine on a 6-50R. Its just not code compliant.

 

[casmurbax]

Here are their images

 

[Norcal]

Here are his images

It is a 50A 125/250V range receptacle & is non grounding dual voltage it not suitable for anything other then cooking equipment.

 

[pattenp]

......
I can't see anyone looking at FLC tables when motor data is on motor.

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Those who don't look at the nec flc table don't care about following the nec. NEC says not to use FLC on motor if HP is listed, you use the table to determine amps.

 

[BD1]

Those who don't look at the nec flc table don't care about following the nec. NEC says not to use FLC on motor if HP is listed, you use the table to determine amps.

Who would buy a motor and look at any table or chart when there's a nameplate on motor. IF it was that important the motor manufacturer would include it with motor.
Motor nameplate provides info.


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[pattenp]

Who would buy a motor and look at any table or chart when there's a nameplate on motor. IF it was that important the motor manufacturer would include it with motor.
Motor nameplate provides info.


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You can pound sand all you want. I'm just saying what's required to wire motor circuits to be NEC compliant.

 

[u2slow]

Who would buy a motor and look at any table or chart when there's a nameplate on motor. IF it was that important the motor manufacturer would include it with motor.
Motor nameplate provides info.

That funny... because CEC (Canadian) says go by the nameplate; unless its not given, then use the table.

 

[BD1]

You pound sand all you want. I'm just saying what's required to wire motor circuits to be NEC compliant.

Code? So all these motor manufacturers that supply a motor name plate with info is wrong and non compliant ? I never read in any installation manual provided that stated refer to NEC code.


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[wyliesdiesels]

Who would buy a motor and look at any table or chart when there's a nameplate on motor. IF it was that important the motor manufacturer would include it with motor.
Motor nameplate provides info.

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Who would do that? An electrician would, if they want to follow code.

Motor manufacturers say to follow NEC code when hooking up the circuit for the motor, so your statement is illogical.

Using the nameplate data only, will cause several code issues.

How could you even properly size the wire if you only used the nameplate data? Wire is to be sized based on HP and the NEC FLC chart. If one took your advice, using the nameplate FLA to size the wire, the wire would be sized incorrectly.

For a 5HP motor, the wire needs to be rated for 35a, which means #10 in pipe or #8 NM-b.

If one used the FLA on the nameplate, then they would use #10 in pipe or #10 NM-b and the nm-b would be the Incorrect size...

Furthermore, if one uses a 6-50p to disconnect a motor, it is not rated for 5HP and can cause issues if the motor is running, such as arcs, that the plug and receptacle are not rated for.

But if you dont care about following code, then by all means, do whatever you want. Size the wire incorrectly. Obviously you dont care...

 

[wyliesdiesels]

Code? So all these motor manufacturers that supply a motor name plate with info is wrong and non compliant ? I never read in any installation manual provided that stated refer to NEC code.


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So tell me. How you would size the wire for the circuit if you only used the nameplate data?

 

[pattenp]

Code? So all these motor manufacturers that supply a motor name plate with info is wrong and non compliant ? I never read in any installation manual provided that stated refer to NEC code.


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Who said the manufacturer is wrong and non compliant? Nobody. You are mixing apples and oranges. The NEC applies to the supply circuit. If the manufacturer specifies the circuit size then you go by what the manufacturer specifies. The motor data plate alone is not the specified instructions for supplying the proper circuit size.

 

[wyliesdiesels]

Here are their images

Those are wrong. there is no ground on that plug or outlet.

It is 10-50 for use with old stove circuits.

 

[cplnorton]

sorry guys I was hosting them thru imgur.

So I need to run a whole new wire then. Correct?

 

[^&right]

My .02. I ran (I believe) 6 gauge to 3 different 240v outlets in my shop when it was done. my compressor is a true 5hp motor industrial unit. Used the thickest pigtail I could find and outlet to match on a 50 amp breaker. 6 years now, now issues. YMMV

 

[pattenp]

sorry guys I was hosting them thru imgur.

So I need to run a whole new wire then. Correct?

That's the best thing to do.

 

[sberry]

It is a 50A 125/250V range receptacle & is non grounding dual voltage it not suitable for anything other then cooking equipment.

It really aint even good for that anymore,,,

 

[mm08822]

sorry guys I was hosting them thru imgur.

So I need to run a whole new wire then. Correct?

The existing cable should fine for the compressor.

Remove the existing receptacle and replace it with a 5hp rated service disconnect.

The disconnect will also provide a convenient splice point for the final wiring to connect to the compressor.

 

[mm08822]

My .02. I ran (I believe) 6 gauge to 3 different 240v outlets in my shop when it was done. my compressor is a true 5hp motor industrial unit. Used the thickest pigtail I could find and outlet to match on a 50 amp breaker. 6 years now, now issues. YMMV

If the plug is not disconnected under load (many times) it should in reality not be a problem.

Plugs and recepts have to be hp rated for motor loads. If you were in business doing this work and had to have an inspection for this installation, your method would not be used b/c it would fail.

You are 6 years being non-code compliant.

 

[Norcal]

That funny... because CEC (Canadian) says go by the nameplate; unless its not given, then use the table.

The CEC has the same value as used toilet paper in the US, the NEC has the same value in Canada. One can only follow the requirements of the code in force, not other codes, they are not relevant.

 

[Norcal]

It really aint even good for that anymore,,,

It is in existing range installations prior to the adoption of the 1996 NEC.

 

[mm08822]

HF states 5 HP motor needs to be connected to at least 25 amp source.
Add a box and direct wire.
Motor data plate has FLA which would be followed . Wire size is based on amps and breaker required.
I can't see anyone looking at FLC tables when motor data is on motor.

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Motor n/p's tell you what the specs are only for the motor. It does not specify what the fixed building wiring requirements are.

NEC code has changed several cycles ago. For the longest time it used to be the n/p FLA's were used as input to size the minimum wire size required.
Using the old method, it would have been 125% of FLA's = 1.25 x 22 =27.5A.

Under today's NEC requirement, you have to lookup the FLC in the NEC table.

For a 5 hp motor, the FLC =28a. @125% of that value, wire needs a minimum ampacity of 35A.

The maximum cb is not sized according to the wire size in a motor ckt as you stated. It is sized off of the motor FLA's. Typically up to 250% of motor FLA. In this case 55A. Since a 55a cb does not exist, it could go to the next size 60A. Since the OP already has a 50a in place, use it. If it were to trip on startups(unlikely), he has the option to change it out to 60a.

 

[mm08822]

That funny... because CEC (Canadian) says go by the nameplate; unless its not given, then use the table.

A prior NEC code change ended that practice for those in US following NEC.

 

[u2slow]

The CEC has the same value as used toilet paper in the US, the NEC has the same value in Canada. One can only follow the requirements of the code in force, not other codes, they are not relevant.

Jurisdictionally, yes.

However, there is value in learning the reasoning in other Codes, especially when they have different or conflicting rules for the same situations.

IMO, a DIY-oriented forum like this could be a little more practical about electrical advice, while still pointing out applicable Code details.

 

[LS6 Tommy]

Who would buy a motor and look at any table or chart when there's a nameplate on motor. IF it was that important the motor manufacturer would include it with motor.
Motor nameplate provides info.


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"Motor nameplate provides info". Yes, for troubleshooting and motor replacement, not wiring.

Tommy

 

[yatg]

Quite a few conflicting opinions. Decided to do some research for my own install.

NEC Article 430, deals with motors.

430.6(A)(1)
Exception 3 - (paraphrased) If the motor is marked with both HP and FLC
(aka FLA), use the FLC to determine the ampacity of the conductors.

430.22 Single Motor. Conductors that supply a single motor
used in a continuous duty application shall have an ampacity of
not less than 125 percent of the motor full-load current rating,
as determined by 430.6(A)(1), or not less than specified in
430.22(A) through (G)

In the OPs case, FLC = 22A * 1.25 = 27.5A conductors.

Misc:
Compressors are not covered by the NEC Appliances article.
Compressors are considered continuous duty motors.
The nameplate contains a lot of info that could be used in sizing, SF, Time, Temp, Code.