Help with new air compressor

[gapfast]

I just picked up a devilbiss 432.
Baldor 5hp motor.
Volts:208-230
Amps:25.5-24.
This compressor will be outside, under my covered back porch. There is some type of breaker box with the compressor.
-30amp breaker ok?
-10-2 wire ok?
-ok to mount box outside to brick wall?
-plug ok outside?
As you can tell I know nothing bout power.
My worries are if the house burned down, I don't want them to blame it on my wiring work.

 

[47p2]

My worries are if the house burned down, I don't want them to blame it on my wiring work.

If you don't know what you are doing then why not call in the professionals!!!

 

[Tim The Tool Man]

As you can tell I know nothing bout power.
My worries are if the house burned down, I don't want them to blame it on my wiring work.

If you indeed know nothing about power/electric then you should hire an electrician.

None the less to answer your questions:
-30amp breaker ok? NO 40 or 50 amp
-10-2 wire ok? NO 8-2 (or 8-3)
-ok to mount box outside to brick wall? YES
-plug ok outside? I WOULD RECOMMEND YOU HAVE IT HARD WIRED

"There is some type of breaker box with the compressor." That is probably a magnetic switch.

 

[e-tek]

If you don't know what you are doing then why not call in the professionals!!!

Because he's a REAL man with an interest in DIY that's why! What kind of an answer is yours for someone on GarageJournal? Get with the program.

To the OP - probably best not to advertise your lack of knowledge to avoid the above happening - lol! ....but looks like you've got the basics down. 30A for sure but I would wire it direct - no plugs.

 

[pattenp]

Here's some info to educate yourself.

Info from: http://www.jcrproductions.com/

Basic Motor Overcurrent Selections Using An Inverse Time Breaker On A 5 h.p., 230 Volt, Single Phase Motor.

When it comes to overcurrent protection for motors, the rules for sizing the protective device as stated in Article 240 are not applicable. When you are working with motors and motor circuits you are dealing with a "different animal" as compared to other resistive loads and their supply circuits. Motors do not always draw a constant or steady amperage as resistive loads normally do. Therefore, with the exception of torque motors, (as given in 430.52(D)) overcurrent protective devices are rated or set according to the values given in Table 430.52 for the device to be used.

For our single phase motor rated 5 h.p. and 230 volts, Table 430-248 states that the amperage to be considered for this motor is to be 28 FLA (full load amperes). Having determined the FLA, it is now time to follow the requirements of section 430.52(C)(1). This section tells us that when sizing our overcurrent device for our motor, we are not to exceed the values as given in Table 430.52. When using an inverse time breaker for the overcurrent protective device, the value given in the table to be used is not to exceed 250% of the motors full load current rating. In order to size the overcurrent device, this percentage is to be simply multiplied by the motor's full load current rating or FLA as shown in the following calculation:
The current rating of our motor is 28 amperes. Therefore, 28 amperes X 250% = 70 amperes
Based on this calculation, an inverse time breaker would be installed in this motor circuit at a maximum initial rating of 70 amperes.

Earlier in this article, motor circuit calculations were referred to as a "different animal". We will now expose the reason for this descriptive statement. We have determined by calculation that the inverse time breaker used for this motor, and its condition of use, is to be rated at 70 amperes. Using the branch circuit calculation requirements of 430.22(A), we find that our minimum permitted branch circuit conductor size (using 430.22(A), Table 310.16, and 110.14(C)(1)(a)(4)) is a #10 THW. Some contractors and inspectors who are operating within the general overcurrent guidelines of Article 240 find a #10 THW supplied by a 70 ampere breaker to be Unacceptable, Incorrect, or just plain SCARY! This can only be due to a lack of understanding with respect to the relationship between overload and overcurrent devices and their respective duties.

Just to set the record straight, in this motor circuit, not only is a 70 ampere breaker supplying the #10 THW conductor acceptable code, IT IS PERFECT CODE!

In closing, the relationship between overload and overcurrent protection in motor and motor compressor applications will be presented in a separate article in the near future. For those who may want an advance peek into this future article please review section 430.31 and remember.... there is more here than meets the eye!

Relax and have fun with your new motor overcurrent knowledge, and in your motor and motor compressor circuits STOP protecting your conductors in accordance with their ampacities as stated in section 240.4. IT DOES NOT APPLY TO MOTOR APPLICATIONS!

 

[gapfast]

If you don't know what you are doing then why not call in the professionals!!!

I did. Me posting is calling in the professionals!

 

[gapfast]

Because he's a REAL man with an interest in DIY that's why! What kind of an answer is yours for someone on GarageJournal? Get with the program.

To the OP - probably best not to advertise your lack of knowledge to avoid the above happening - lol! ....but looks like you've got the basics down. 30A for sure but I would wire it direct - no plugs.

Thanks for the tip!
Y no plug? That might be a good thing. I won't have to worry about a plug outside.

 

[gapfast]

Pattenp: thanks for your reply, good read, over my head, but good read.
Here's a few pics.
Whats the box?
Is it ok to use the breaker as on off switch?

 

[pattenp]

Not sure what the box is, but it looks like overload protection with the red reset button. I'm sure someone will chime in with what it exactly is. As far as using the breaker as an on off switch, that's okay but not the ideal use of a breaker. Also if the servicing breaker is in the house you need to add a disconnect switch box near the compressor.

 

[Zeke]

Your box with the reset button doesn't appear to me to be rated for exterior use. I don't think you'll be using it anyway. Get a good push button switch with a water proof box and cover.

What's the skinny on the go-kart? Looks like it might be an old Bug Kart. They have "historic" races for karts now.

 

[Charles (in GA)]

The box is most likely the magnetic motor starter. I'll bet that 5hp Baldor does not have an overheat reset in the end of the motor. A motor starter serves two purposes, it provides a relay to make and break the power to the motor, without having to run the full load of the motor thru the pressure switch. Instead, the pressure switch only operates the coil of the starter to move the starter's contacts. It is nothing more than a relay. The second purpose of it is that there is probably an overheat sensor in it that will interrupt the coil circuit and cause the motor to shut off. It won't start up again till you push the reset button. The thermal overload simulates the load of the motor with a heater coil. Should the motor begin to draw more than the normal amount of current, the heater element will get hotter, and a thermal switch will interrupt the circuit to the coil and pressure switch.

With a motor of this size, it is best to not use a plug and cord setup as the plug, while capable of handling the motor's normal running amperage, will not easily handle the high loads of starting, which can run as high as 200 amps for this motor, for a split second. Anytime you use plugs or switches on motors, make sure that along with the amperage rating, that the device is "motor rated" for the horsepower you intend to run.

Install a disconnect on the outside, it is required, and hardwire the compressor to it. You must have some sort of disconnect within 50 ft and within line of sight from the panel that supplies the compressor. Being outside, you do not have line of sight, so you have to have a disconnect. A plug and receptacle is a legal disconnect, but with a 5 hp motor, it is not a good thing to use, especially since the compressor is not portable and you won't be taking it anywhere.

You can buy a 60 amp outdoor rated disconnect like that used for the compressor/condenser units of a central A/C for about $10 to $15 at Lowes or Home Depot.

Do yourself and the motor another favor and install heavier wire, use #8, and you won't see voltage losses during startup like you would see with #10.

Zeke is very likely correct, the box is probably not listed as raintite and you may need to mount it on the inside of the wall and run the wires thru the wall to the compressor. Again, the disconnect needs to be on the outside, adjacent to the compressor.

Charles

 

[gapfast]

Your box with the reset button doesn't appear to me to be rated for exterior use. I don't think you'll be using it anyway. Get a good push button switch with a water proof box and cover.

What's the skinny on the go-kart? Looks like it might be an old Bug Kart. They have "historic" races for karts now.

Kart was given to me. Gonna get it goin for the youngen. Streaker brand.

 

[gapfast]

Charles, thanks for the wisdom.
I will include a picture of inside the box to help clear it up.
-gonna run #8 now
-gonna get a outdoor rated disconect and hardwire now
-gonna relocate mystery box to inside now

-

 

[47p2]

Because he's a REAL man with an interest in DIY that's why! What kind of an answer is yours for someone on GarageJournal? Get with the program.

To the OP - probably best not to advertise your lack of knowledge to avoid the above happening - lol! ....but looks like you've got the basics down. 30A for sure but I would wire it direct - no plugs.

Well since you guys only have 120-240- volts I guess you can't really do much harm other than give yourself a slight jolt

 

[ForceFed70]

To elaborate on the outside stuff - It's OK provided:
1) You use outdoor rated boxes along with covers, etc
2) I think you are required to add GFCI protection

 

[hidollartoys]

Charles, thanks for the wisdom.
I will include a picture of inside the box to help clear it up.
-gonna run #8 now
-gonna get a outdoor rated disconect and hardwire now
-gonna relocate mystery box to inside now

-

Charles and pattenp are both mostly correct but failed to mention that for motors the conductors are required to be rated for the "table amps" X 125%. In your case the conductors will need to be rated for 35 amps. Your choice of #8 will meet these requirements.

 

[Charles (in GA)]

If you have to disconnect anything to run the wires thru the wall, or replace the wires with longer ones, be sure and take lots of close up pics and make notation of where each wires comes from and goes to. Much easier to do this before hand than to try and figure it out afterward. That is a very old starter and I would have to see it in person to figure it out.

Put the disconnect outside, and run wires thru the wall to it, and then from it back inside to the starter box. Mount the starter box, and run its wires outside to the motor, and the pressure switch. It will be very easy to disconnect the wires at the motor and pressure switch, as this is straight forward with a minimum of terminals per wire (BX, MC or whatever it is). Putting that starter inside will make it last for years, leaving it outside, even under a roof, will shorten its life considerably.

Charles

 

[pattenp]

Charles and pattenp are both mostly correct but failed to mention that for motors the conductors are required to be rated for the "table amps" X 125%. In your case the conductors will need to be rated for 35 amps. Your choice of #8 will meet these requirements.

The 125% factor X table amps is for continuous duty application, motors that run continuously for 3 or more hours. So is the 125% factoring required in this case?

Edit: Or, should you use the factors for periodic or varying duty application?

 

[Charles (in GA)]

Motors over 1/8 hp always require the 125% factoring, unless the manufacturer of the equipment specifies otherwise.

Charles

 

[pattenp]

Motors over 1/8 hp always require the 125% factoring, unless the manufacturer of the equipment specifies otherwise.

Charles

I was uncertain of the constant use of the 125% when the NEC has a section for "Other Than Continuous Duty", when the motor is used in a varying duty or periodic application. The table 430.22(e) is to be used and the factors are to be applied to the name plate amps. The table gives as an example 140% for periodic, intermittent etc. I was wondering if an air compressor could be considered a non continuous duty application.

 

[Zeke]

If you have to disconnect anything to run the wires thru the wall, or replace the wires with longer ones, be sure and take lots of close up pics and make notation of where each wires comes from and goes to. Much easier to do this before hand than to try and figure it out afterward. That is a very old starter and I would have to see it in person to figure it out.

Put the disconnect outside, and run wires thru the wall to it, and then from it back inside to the starter box. Mount the starter box, and run its wires outside to the motor, and the pressure switch. It will be very easy to disconnect the wires at the motor and pressure switch, as this is straight forward with a minimum of terminals per wire (BX, MC or whatever it is). Putting that starter inside will make it last for years, leaving it outside, even under a roof, will shorten its life considerably.

Charles

That is a lot of trouble for the OP. Is there a waterproof utility box that he can mount on the exterior wall and place the starter/reset and his disconnect all in one? Going inside to reset the starter would be inconvenient at best. Also, he could lock it up as well if he so desired.

Here is a Hoffman # A12R1210HCR

Application

These enclosures have a size range of 6 x 4 x 4-in. to 12 x 12 x 10-in. and meet basic functionality requirements for applications that require protection from rain, sleet, snow or dripping water.

Features

• Drip-shield top and seam-free sides, front and back
• Plated steel hinge has stainless steel pin
• Weldnuts provided for mounting optional panels
• Provisions for padlocking on zinc-plated draw-pull catch
• Knockouts on bottom of enclosure
• No gasketing

Specifications

• 16 gauge galvanized steel.

 

[hidollartoys]

I was uncertain of the constant use of the 125% when the NEC has a section for "Other Than Continuous Duty", when the motor is used in a varying duty or periodic application. The table 430.22(e) is to be used and the factors are to be applied to the name plate amps. The table gives as an example 140% for periodic, intermittent etc. I was wondering if an air compressor could be considered a non continuous duty application.

You are referring to motors per Table 430.22E (2005 code, sorry dont have later versions here at home)which pertains to duty cycle service and does not pertain to this application.

All motors that are not specifically addressed in the table or those allowed by the AHJ are to have conductors rated at 125% of table amps.

 

[gapfast]

Charles and pattenp are both mostly correct but failed to mention that for motors the conductors are required to be rated for the "table amps" X 125%. In your case the conductors will need to be rated for 35 amps. Your choice of #8 will meet these requirements.

Ok if I run#8. I still only have a 30amp breaker. Do I need a 40?

 

[gapfast]

That is a lot of trouble for the OP. Is there a waterproof utility box that he can mount on the exterior wall and place the starter/reset and his disconnect all in one? Going inside to reset the starter would be inconvenient at best. Also, he could lock it up as well if he so desired.

Here is a Hoffman # A12R1210HCR

Application

These enclosures have a size range of 6 x 4 x 4-in. to 12 x 12 x 10-in. and meet basic functionality requirements for applications that require protection from rain, sleet, snow or dripping water.

Features

• Drip-shield top and seam-free sides, front and back
• Plated steel hinge has stainless steel pin
• Weldnuts provided for mounting optional panels
• Provisions for padlocking on zinc-plated draw-pull catch
• Knockouts on bottom of enclosure
• No gasketing

Specifications

• 16 gauge galvanized steel.

I'm liking thia idea... what say ye?

 

[pattenp]

Ok if I run#8. I still only have a 30amp breaker. Do I need a 40?

Since you're using #8 just go ahead and use a 40A. Shouldn't cost you any more. If you already have the 30A, just use it. If the 30A trips then you know you need a 40A.

 

[bsaint]

Of everything, I would run 10-3 for a ground.

 

[pattenp]

Of everything, I would run 10-3 for a ground.

Say again? 10-2 is 2 conductors plus a ground. 10-3 is 3 conductors plus a ground. Unless you are talking flex cord. I was assuming the OP was using NM terms.

 

[hidollartoys]

Since you're using #8 just go ahead and use a 40A. Shouldn't cost you any more.

If you experience nusiance trips at start-up you can upsize the breaker up to 250% of the table amps, which in this case is 28 amps. So per code you could use a breaker rated up to 70 amps.

 

[Charles (in GA)]

I was uncertain of the constant use of the 125% when the NEC has a section for "Other Than Continuous Duty", when the motor is used in a varying duty or periodic application. The table 430.22(e) is to be used and the factors are to be applied to the name plate amps. The table gives as an example 140% for periodic, intermittent etc. I was wondering if an air compressor could be considered a non continuous duty application.

I just saw that myself and was going back to correct my post. Generally there is no argument that "bigger is better" and #8 will prevent potential problems from cropping up. It is one of those arguments of discussion not worth it as the difference in the price of wire is minimal vs the problems that could arise from minimal or undersize wiring.

My 7.5 hp compressor peaks at about 190 amps on startup.

Charles

 

[Charles (in GA)]

I tend to run a neutral even if I don't need it, and end up capping it off. Makes for less hassles later if the wire/circuit gets re purposed later or the neutral is found to be needed on a new compressor or other device.

Charles

 

[bsaint]

Say again? 10-2 is 2 conductors plus a ground. 10-3 is 3 conductors plus a ground. Unless you are talking flex cord. I was assuming the OP was using NM terms.

meant neutral.

 

[gapfast]

Lowes didn't have one of those big boxes to put the starter in. Ill check home depot

 

[Zeke]

No, empty equipment boxes are going to have to come from an electrical supply house. Or, you can get one online easily. But don't forget your local salvage place. We have a couple in SoCal (that I know of) that carry all kinds of military and manufacturing surplus items and some are really cheap.

I bought some really cool old style aircraft toggle switches that are on the dash of my '44 Jeep. They are so cool that most of them are just filling holes and don't do anything. They had miles of wire cable from a few conductors to dozens. Just goes to show you that you can buy almost anything used if you look.

 

[Charles (in GA)]

Ok if I run#8. I still only have a 30amp breaker. Do I need a 40?

I would seriously consider a 40. You stand a good chance of blowing the 30 on startup, and the 40 would be quite legal.

Charles

 

[ddawg16]

Just run an extension cord like everyone else does....one of those 22awg HF cords should do the trick.....


Now that I have my funny out of the way.....

Find a local electrcal supply....they will have a good selection of Hoffman, Weidmeirer, etc boxes that will work. Don't be afraid to by a bigger one. I personally would want a NEMA 4X with a disconnect. That way you can turn off power there at the compressor.

No need for a plug.....just use seal tight (flexible plastic conduit) or regular conduit from the compressor to the box. Hardwire that baby....no plugs needed. In fact, I would move the contactor you have to the new box....put all of it on one place.

Note....you need to confirm the voltage on your contactor coil. This is the coil that actually pulls in the contactor. This allows the pressure switch to work on low voltage & current.....you do NOT want to put 30+ amps through a pressure switch. If you contactor coil is 120Vac, then you will need a neutral out to your box. One leg of your 240Vac and the neutral will go to the contactor/pressure switch wiring.

 

[Norcal]

Just run an extension cord like everyone else does....one of those 22awg HF cords should do the trick.....


Now that I have my funny out of the way.....

Find a local electrcal supply....they will have a good selection of Hoffman, Weidmeirer, etc boxes that will work. Don't be afraid to by a bigger one. I personally would want a NEMA 4X with a disconnect. That way you can turn off power there at the compressor.

Have you priced NEMA 4X enclosures? If, or when, I suggest some adult diapers , 'cause when you do your going to need them. NEMA 3R is fine.
NEMA 4X is watertight, corrosion resistant & in most but not all cases, $tainless $teel.
A cheap pullout A/C disco is also fine, they can be bought at a big box store for less then $10, 30A,60A, or 60A non-fusible.

Now a combonation starter would be nice, like in the photo below, it's one of the only two single phase combo starters that have ever seen, a combo starter has the disconnect switch or circuit breaker & motor starter in one enclosure.

Back part of that building no longer exists, but was rebuilt in 2011.

 

[gapfast]

Wow!! The boxes are more than I expected. I think that it would be better than relocating the starter or whatever it is though.
I will pull the cover off and check voltage...

 

[Charles (in GA)]

If the existing starter unit is still connected to the compressor by the MC/BX that we see in the pics, the OP could easily mark the wires and disconnect from the pressure switch (two wires and a ground) and the motor (another two wires and a ground) and then pass the disconnected wires thru the wall from the inside and reconnect them to the compressor. This will leave the MC/BX exposed but under the roof... could be covered with some sort of sleeving........ or if the wires are not long enough, they could, one at a time, be replaced with something longer and then reconnected. None of this is difficult for even someone new to electrical work.

You just don't want the stuff in that motor starter to get wet or damp, too expensive to replace.

Charles

 

[ddawg16]

Norcal...your right....4x would be pricey....I take it for granted...I just spec it but never see the invoice....3r would be fine....just not a NEMA 1

Personally, I'd be scouring CL or fleabay for a used one. Disconnects don't really wear out...unless someone is using it as an on/off switch every day

 

[Norcal]

Norcal...your right....4x would be pricey....I take it for granted...I just spec it but never see the invoice....3r would be fine....just not a NEMA 1

Personally, I'd be scouring CL or fleabay for a used one. Disconnects don't really wear out...unless someone is using it as an on/off switch every day

Not just pricey, really really pricey for 4X. Let the buyer beware on CL or Ebay.