Wiring Air compressor

[medic502]

Harbor Freight 93274 Compressor.

Honestly I have never ran 220V but have installed 110V circuits and I have a question concerning wire size.
The manual says 40 amp breaker...This should require 8 gauge wire from what I have read.
My question is will 8 gauge wire fit in these connections?
Also my box already has a 50 amp breaker that came with it... Could I use this 50 amp breaker instead of the 40?

Thanks for the Help.

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[sberry]

Doesnt look like any reason that the 50 wouldnt work. The breaker isnt really per wire size like it would be for a general circuit with multiple recepts on it. In some cases a 50 breaker could be used with 12 wire.
I will have to give HF a couple of points here for trying to be helpful for including some general wiring instructions. They gave a lay version, there is a range of breakers that would work. It needs 8 wire if its cable, 10 individual conductors in pipe.

 

[pattenp]

I assume you know the compressor needs to be hardwired? No cord and plug.

 

[medic502]

Yes... I do understand it needs to be hard wired... Just wasn't sure if the 8 gauge wire would fit but in the connection to the compressor.

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[wyliesdiesels]

Thats a 5HP compressor so you need #8/2 NM-b or #10 THWN in pipe.

If compressor is not within sight of and further than 50' away from breaker panel then you need a disconnect.

Breaker can be max 250% of FLC which is 35a for 5HP but 50a breaker should be fine if you already have that.

 

[medic502]

Thank you for the response concerning the breaker size.

The compressor is 15 feet from the breaker box.

My concern is looking at the connections would size 8 wire fit in these openings indicated in the inserted picture or would I need to attach a spade connector (if that is an option) like in the factory connections also in the picture.

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[Habrot]

Without seeing the inside of the motor, and tracing the wires from the coils and switches, etc, it's at best difficult to guess about the terminals; there's no convention that I know of.

 

[sberry]

Stick a little piece in and see.

 

[pattenp]

You need to use flex conduit to the compressor from the wall. Should not use NM-b. You can use #8/2 NM-b from panel to box on wall and step down in size to a #10 A/C whip from box to compressor.

I think this is convenient to use as a jbox plus it gives you a switch at the compressor,
https://www.homedepot.com/p/Square-...kW-Non-Fuse-AC-Disconnect-QO200TRCP/202353314

here's a A/C whip.. https://www.homedepot.com/p/Southwi...lic-PVC-Conduit-Cable-Whip-55189407/202210500



*

 

[sberry]

That is really the ideal way to do it.

 

[Norcal]

You need to use flex conduit to the compressor from the wall. Should not use NM-b. You can use #8/2 NM-b from panel to box on wall and step down in size to a #10 A/C whip from box to compressor.

I think this is convenient to use as a jbox plus it gives you a switch at the compressor,
https://www.homedepot.com/p/Square-...kW-Non-Fuse-AC-Disconnect-QO200TRCP/202353314

here's a A/C whip.. https://www.homedepot.com/p/Southwi...t A/C disco, much cheaper and easier to wire.

 

[sberry]

I am a wire nut fan, not adding a piece more than I need in this type of circuit.

 

[Norcal]

I am a wire nut fan, not adding a piece more than I need in this type of circuit.

The NEC is a minimum standard and I would rather have the disco close then walk some distance to shut it off when servicing it, and pullout type discos are cheap.

 

[sberry]

You get no argument from me that they are cheap.

 

[sberry]

In my case the breaker box is within reach, the op is 15 ft. There has literally been times its been years since the comp was off.

 

[pattenp]

Buy a non fusible 60A pullout A/C disco, much cheaper and easier to wire.

How do you figure a pullout A/C disconnect is easier to wire? Yes, you can save about $6-$7 using a non-fused pullout, but I just like the switch.

 

[Citation]

This compressor's pressure switch appears to include an on/off function like many 120v compressors. Assuming the circuit panel was say more than 50ft away does it still need a local wall switch/disconnect? I had always assumed that rule applied to compressors that had no built in power switch (ie no power switch as part of the pressure switch or mag starter).

 

[wyliesdiesels]

This compressor's pressure switch appears to include an on/off function like many 120v compressors. Assuming the circuit panel was say more than 50ft away does it still need a local wall switch/disconnect? I had always assumed that rule applied to compressors that had no built in power switch (ie no power switch as part of the pressure switch or mag starter).

a pressure switch with on/auto-off function does not count as a disconnect. nor does a switch that is part of the mag starter relay wiring.

And if its more than 50' away it needs a disconnect. The disconnect is for servicing.

 

[Citation]

a pressure switch with on/auto-off function does not count as a disconnect. nor does a switch that is part of the mag starter relay wiring.

And if its more than 50' away it needs a disconnect. The disconnect is for servicing.

I didn't realize that. The two hardwired compressors I've helped with were both within feet of the panel so this wasn't an issue.

What counts as a disconnect? I'm assuming it must disconnect both L1 and L2. Does it need to have a positive disconnection? For example, when I look on HD's website I see things like a 30 A double pole "light switch"
https://www.homedepot.com/p/Leviton...ble-Pole-Switch-White-R62-03032-2WS/100356941

Assuming the 30A rating was sufficient for a 15A motor, would that count or does it need some way to prevent easy reactivation? How does the code view that switch vs this pull type disconnect
https://www.homedepot.com/p/GE-60-A...on-Metallic-AC-Disconnect-TPN60R1CP/100569466

or this safety switch?
https://www.homedepot.com/p/GE-30-A...PIPHorizontal3_rr-_-305904198-_-202978650-_-N

I'm asking out of interest. I've done a decent amount of electrical work but most at the electronics level where a mistake burns of a micro or shorts your power supply. Less in the CAT 3 and above land hence why I ask.


What are the rules for the disconnect? Does it have to be a double throw? I don't know if that is the correct electricians term but I'm thinking like a double pole switch where both L1 and L2 would be disconnected at the same time. From a pure schematic POV I would consider a disconnect like this a STDP switch since it opens/closes two connections at once.
https://www.homedepot.com/p/GE-60-A...on-Metallic-AC-Disconnect-TPN60R1CP/100569466

 

[PT Doc]

I didn't realize that. The two hardwired compressors I've helped with were both within feet of the panel so this wasn't an issue.

What counts as a disconnect? I'm assuming it must disconnect both L1 and L2. Does it need to have a positive disconnection? For example, when I look on HD's website I see things like a 30 A double pole "light switch"
https://www.homedepot.com/p/Leviton...ble-Pole-Switch-White-R62-03032-2WS/100356941

Assuming the 30A rating was sufficient for a 15A motor, would that count or does it need some way to prevent easy reactivation? How does the code view that switch vs this pull type disconnect
https://www.homedepot.com/p/GE-60-A...on-Metallic-AC-Disconnect-TPN60R1CP/100569466

or this safety switch?
https://www.homedepot.com/p/GE-30-A...PIPHorizontal3_rr-_-305904198-_-202978650-_-N

I'm asking out of interest. I've done a decent amount of electrical work but most at the electronics level where a mistake burns of a micro or shorts your power supply. Less in the CAT 3 and above land hence why I ask.


What are the rules for the disconnect? Does it have to be a double throw? I don't know if that is the correct electricians term but I'm thinking like a double pole switch where both L1 and L2 would be disconnected at the same time. From a pure schematic POV I would consider a disconnect like this a STDP switch since it opens/closes two connections at once.
https://www.homedepot.com/p/GE-60-A...on-Metallic-AC-Disconnect-TPN60R1CP/100569466

Disconnects must be motor rated. If you go by amps only then you can have issues. Similarly a 50 amp plug is not rated for a 5 hp motor but the 50 amp breaker would cover amp requirements of the 5 hp motor.

 

[PT Doc]

Look at Leviton motor rated disconnects. For example, MS602 is a single phase 60 amp disconnect. MS603 is a three phase 60 amp disconnect.