Plasma/compressor outlet/disconnect

[REKIII]

I'm having some trouble figuring out what I need. I've read through some other threads and have learned I will need a disconnect on this equipment. I've always known about disconnects on AC condensers, but am new to it otherwise. From what I read, it seems I will need a disconnect on 50amp things when there is not a line of sight to the panel.

I'm replacing a small compressor with a large single phase Campbell hausfield unit. I was told I need a 50amp breaker. I'm running 6GA. It seems that a disconnect box would work best, but I can only find 60 amp disconnects, or 50amp spa panels. What do I need?

The same goes for my plasma cutter. I'm setting up a CNC plasma table with a Powemax85 Hypertherm cutter.....they said I will need a 50 amp for this as well. I was hoping to put this one on an outlet, so I can take the cutter to other locations if necessary. Do I still need a disconnect with an outlet? I will be running a second set of 6GA for this.

Thanks for any help.

 

[pattenp]

Compressor with motor larger than 3hp should be hardwired and if you need a disconnect because of distance from panel a 60A A/C disconnect works well. Welder and plasma cutter does not need a separate disconnect, the plug is the disconnect.

This is a cheap solution for a disconnect... http://www.lowes.com/pd_95578-82364..._clickID=34342d68-f7da-44ac-b97c-7e61c304e440

Edit: your compressor may not need a 50A circuit. Circuit is sized based on motor HP unless the manufacturer specifies the circuit size..

 

[REKIII]

Can I put a 60amp disconnect on a 50amp breaker? I intend to hardwire the compressor.

Thanks!!

 

[REKIII]

I looked at your link, I would assume then that a 60amp is OK to run on a 50 amp breaker.

 

[CNGsaves]

OP . . . . post up picture of motor plate on compressor. The HP (horsepower) determines wire size and breaker.

Also, what is distance for wiring from subpanel to compressor ??

GJ Sparky's will be able to give you best advice with that information.

 

[pattenp]

Can I put a 60amp disconnect on a 50amp breaker? I intend to hardwire the compressor.

Thanks!!

The disconnect is just a switch. It needs to be rated at as much or more than the circuit size, not less. Also the A/C disconnects are motor HP rated and I believe it's good to up to 10HP.

 

[sberry]

The welders may not need 6 wire either.

 

[wyliesdiesels]

I'm having some trouble figuring out what I need. I've read through some other threads and have learned I will need a disconnect on this equipment. I've always known about disconnects on AC condensers, but am new to it otherwise. From what I read, it seems I will need a disconnect on 50amp things when there is not a line of sight to the panel.

I'm replacing a small compressor with a large single phase Campbell hausfield unit. I was told I need a 50amp breaker. I'm running 6GA. It seems that a disconnect box would work best, but I can only find 60 amp disconnects, or 50amp spa panels. What do I need?

The same goes for my plasma cutter. I'm setting up a CNC plasma table with a Powemax85 Hypertherm cutter.....they said I will need a 50 amp for this as well. I was hoping to put this one on an outlet, so I can take the cutter to other locations if necessary. Do I still need a disconnect with an outlet? I will be running a second set of 6GA for this.

Thanks for any help.

u got some things mixed up here.

The disconnect requirement applies only if the motor is more than 50' from and not within sight of the breaker panel. This requirement has nothing to do with 50amps.

What is the motor HP rating?

 

[Norcal]

Safety switches, A/C discos come in 30A, or 60A, and safety switches go from 60 to 100, then 200,400, ampere ratings, you may use larger but not smaller, & if a fusible type is used there is a range of fuse ratings that may be used, for example 60A fuse clips accept 35,40,45,50,60 amp fuses.

 

[REKIII]

OK, All that makes sense.

I will get the HP on the motor, but the place I bought it from said 50amp.....and from what I read, you need 6GA for 50amp, but tell me if I'm wrong.

I grabbed a normal non-fused 60amp disconnect. The compressor and plasma will have 50' of wiring between them and the panel, but the panel is in a room.

There are no welders, only plasma and compressor.

Really appreciate the help guys. Great forum, great guys.

 

[pattenp]

OK, All that makes sense.

.....and from what I read, you need 6GA for 50amp, but tell me if I'm wrong.

For a general purpose single 50A outlet circuit that is correct. But for motor circuits and welder circuits there are allowances for larger breakers than what the amp size of the wire would normally call for.

 

[REKIII]

7.5HP Single Phase

 

[pattenp]

That 7.5 HP motor should be hardwired using #6 NM-b or (#8 THHN in conduit) on at least a 50A breaker. The breaker size can be increased if you have nuisance tripping on startup. The motor should have it's own overload protection.

 

[REKIII]

That is the plan. Thank you for verifying!

 

[bobmulry]

7.5HP Single Phase

Hi,

I am confused about this info plate.....

7.5 HP @ 230 volts and it draws 31 amps??????????????????

What ever happen to the 12 amps per HP @ 120 volts?????

I would think that a 7.5 HP motor at 230 volts would be rated at 45 FLA?????

What happened????

I am so confused.......

Bob

 

[pattenp]

Hi,

I am confused about this info plate.....

7.5 HP @ 230 volts and it draws 31 amps??????????????????

What ever happen to the 12 amps per HP @ 120 volts?????

I would think that a 7.5 HP motor at 230 volts would be rated at 45 FLA?????

What happened????

I am so confused.......

Bob

Where did you get 12A @ 120V per HP?

 

[REKIII]

Hi,

I am confused about this info plate.....

7.5 HP @ 230 volts and it draws 31 amps??????????????????

What ever happen to the 12 amps per HP @ 120 volts?????

I would think that a 7.5 HP motor at 230 volts would be rated at 45 FLA?????

What happened????

I am so confused.......

Bob

I really don't know a lot about....well anything. I can't tell you why it is what it is, but it's the way it came. Is the motor Junk?

 

[CNGsaves]

^ ^ ^ You're fine OP. PattenP is getting you all the CORRECT information.

That 7.5 HP Baldor is an AWESOME motor . . . one of the best. Post up PIC's of the rest of compressor. That has to be a very impressive setup that you DO want to hard wire up properly as PattenP as detailed.

 

[Aceman]

That is a large single phase motor for a residential application. Most utilities want to be notified first before you try to run anything larger than a 3-5HP single phase motor.

That 7.5 HP motor should be hardwired using #6 NM-b or (#8 THHN in conduit) on at least a 50A breaker. The breaker size can be increased if you have nuisance tripping on startup. The motor should have it's own overload protection.

The Baldor's that I've wired have stated right on the nameplate "thermally protected", I don't see that on his. Since this is a new compressor, I'd assume it came with it's own combination starter??

I would also start with a 60 amp breaker as well. I don't like to start at the NEC minimum for motor breaker sizes. Especially for loads that start hard. NEC allows a 50-100 amp breaker to start with.

 

[wyliesdiesels]

OP did your compressor come with a starter?

 

[REKIII]

Here is the compressor in all it's glory

Here is what I think is the starter, or at least the contactors:

Here is the whole motor