Help me wire in a air compressor!

[swampthang]

Ok I"ve made my mind up this is the compressor I'm going to buy. http://www.northerntool.com/shop/tools/product_200350477_200350477 What gauge of wire and breaker do I need to run this? I read on another site that it needs an 80 amp breaker. That seems kind of big to me. Does anyone have any experience with this? I plan on putting the compressor about 25ft from my breaker box but the wires would need to be ran up the wall along the ceiling and back down the wall to a junction box where I can run it into a flex line to the compressor.

 

[DBendr]

Nah. 40 amp @ 230 will work but 50 is a better bet.I have an Atlas 7.5 on 50. Never had a problem. Put a box with a disconnect switch to wire into.You want it right there for maintainence.

 

[DBendr]

Run your 3 wires in 1/2" or 3/4" gray electric PVC.
Here's a wire chart
http://www.amplepower.com/primer/gauge/

 

[2Big2Ride]

Run your 3 wires in 1/2" or 3/4" gray electric PVC.
Here's a wire chart
http://www.amplepower.com/primer/gauge/

That chart looks like it is for 12VDC, not for 240/120VAC.

 

[wyliesdiesels]

Ok I"ve made my mind up this is the compressor I'm going to buy. http://www.northerntool.com/shop/tools/product_200350477_200350477 What gauge of wire and breaker do I need to run this? I read on another site that it needs an 80 amp breaker. That seems kind of big to me. Does anyone have any experience with this? I plan on putting the compressor about 25ft from my breaker box but the wires would need to be ran up the wall along the ceiling and back down the wall to a junction box where I can run it into a flex line to the compressor.

First off what size service do u have? Any other large electric loads? 7.5HP is a good sized load on startup.

U said it will be 25' from the panel? Is it within sight of the panel? If so then u dont need a disconnect.

U will need 50a rated wire. This is because wire for motor circuits is sized @ 125% of NEC table FLC. 7.5hp is 40a FLC.

So use #6/2 NM-b or #8 THHN in pipe. If u use THHN in pipe u will need 2 #8 and a #10 for the EGC.

U cant use an outlet and plug unless u can find one rated for 7.5HP or more. So it will need to be hardwired.

Breaker can be max 250% of NEC table FLC.

Nah. 40 amp @ 230 will work but 50 is a better bet.I have an Atlas 7.5 on 50. Never had a problem. Put a box with a disconnect switch to wire into.You want it right there for maintainence.

Breaker size depends on motor.

Disconnect isnt required if within 50' of and within sight of the panel.

Run your 3 wires in 1/2" or 3/4" gray electric PVC.
Here's a wire chart
http://www.amplepower.com/primer/gauge/

Wrong chart. Thats for DC 12v....

 

[Aceman]

The very first thing you need to do is contact your power company and let them know you plan on installing a 7.5HP compressor. I'd see if they give you the green light before you start discussing wire/breaker sizes.

 

[swampthang]

I have 200amp service to the property. 200 panel in house and 200 panel in shop. Its split so if one is using little power the other can draw the majority of the 200 amp. I just built the shop so the only power consumption I have in it are led shop lights and one 20 amp outlet as of now. Future plans include a propane radiant tube heater, exhaust fan, 220 mig welder. I havent made my mind up on location of compressor but at the farthest i'd consider would be 25ft from the service panel eye sight. This means running inside the wall up from panel 5ft into attic acrossed 25ft then down inside wall about 6ft to a junction box where I could switch to flex line to compressor.

 

[Norcal]

Aceman's advice is spot on, the PoCo needs to be consulted BEFORE buying a 7.5 HP compressor, they will take a dim view if the compressor causes problems on their end.

 

[Stuart in MN]

The very first thing you need to do is contact your power company and let them know you plan on installing a 7.5HP compressor. I'd see if they give you the green light before you start discussing wire/breaker sizes.

This is a good point. Electric utilities will often have limits on how big an electric motor you can have at a residential service (assuming this is in your home shop) so you don't make all your neighbor's lights dim every time the motor starts.

 

[swampthang]

I live in the country. No neighbors within sight. Power company told me they take care of the power to the meter on the pole thats it, whatever else happens is all on me. I called them and asked when I had power ran to the shed from the pole. They told me I could wire everything myself or hire someone. Sounded like dont bother the power company unless theres a problem with the meter lol.

 

[wyliesdiesels]

Do u have your own trany?

Even if u do, it could still cause a drop on the primary side.

 

[swampthang]

Do u have your own trany?

Even if u do, it could still cause a drop on the primary side.

I guess your talking transformer? The line of power poles along the road stop infront of my house. The last pole along the road before it goes to the pole in my yard has a transformer on it.

 

[Pwrgeek]

Yeah 7.5 HP isn't going to touch the utility primary. If there are other people on the same transformer (unlikely since they aren't in sight) it could affect them. On your stuff if the lights may dim a bit when the compressor kicks on depending on the transformer size.


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[Junkman]

Ok I"ve made my mind up this is the compressor I'm going to buy. http://www.northerntool.com/shop/tools/product_200350477_200350477 What gauge of wire and breaker do I need to run this? I read on another site that it needs an 80 amp breaker. That seems kind of big to me. Does anyone have any experience with this? I plan on putting the compressor about 25ft from my breaker box but the wires would need to be ran up the wall along the ceiling and back down the wall to a junction box where I can run it into a flex line to the compressor.

I like your choice in brand, however, I personally, don't care for splash lubricated compressors, and others might disagree. If you are going to go for a Quincy, then consider purchasing a pressure lubricated compressor. I also don't think that you need to have a 7.5 HP compressor, but that is an individual choice. I have a 5 HP Quincy with the Quincy 325 two stage pressure lubricated head, and it has served me well for 20 years. Here is a Quincy 7.5-HP 80-Gallon Pressure Lubricated Two-Stage QP Pro Air Compressor (230V 1-Phase) that is a more money than the one that you have chosen, however, a pressure lubricated compressor head will outlast your lifetime.

 

[swampthang]

Im not opposed to upgrading to the pressure lube Quincy. This will be used for auto body work and hopefully someday my own home business. I dont want to spend the $ for a rotary screw or 3 phase.