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Air compressor question


BeemerBerg

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I have this little jewel of a compressor in my garage: https://m.harborfreight.com/8-gal-2-hp-125-psi-oil-lube-air-compressor-68740.html

A basic 2 HP, 110 volt, 8 gallon unit. I've plumbed it to an overhead retractable hose reel at the other end of the garage. It's mostly used intermittently: to air up tires, blow dust off, air ratchet, etc., nothing heavy duty.

I've parked the compressor in an inconvenient location—It's a PITA to turn the unit on/off from the ‘unloader swithch' on the compressor. I often forget to turn the darn thing off or pull it's plug when I'm done tinkering, resulting in wifey asking “honey, did you remember to turn off the compressor” as the little guy ‘cycles on' in the middle of the night.

 

Question for electricians: would it be OK to wire a light switch to the compressors dedicated outlet to turn it off/on?

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I'm not an electrician but I do most of my home wiring and I don't see why not. You could always single out that outlet and run the wiring for the switch to a more convenient location. Simple in concept but could be difficult depending on how your wiring is run.

 

You would have to pull that outlet to see if it's in the middle of a chain or the last in line. If the last in line easier to wire the switch, if the middle, you have to fork off the power for the follow on outlets.

 

Make sure your amperage on the switch matches the capability of the amperage on the compressor.

 

Also, I'm not a by the code type wiring guy, I'm a make-it-work guy, so my advice should be taken at your own peril, if you burn your house down, it's not my fault ;)

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Danny caddyshack Noonan

Also not an electrician, but agree with Richard. I would use a 20A rated switch minimum for CYA, they don't cost much more than lower rated. If not at the end of the chain, I would cut the jumpers on the outlet and have the switch only operate one of the sockets. That does two things for you: 1. the other socket is always hot (you always seem to need the socket that you thought you wouldn't need). 2. it removes any concern over switched chained outlet strings as they remain hot too.

Pull the wires, run the hot into the switch, extend the hot back out of the inlet into the other socket and then off to the remaining outlets, then run the switched hot to the compressor socket with nothing coming out. I'm assuming it's ok to switch hot and not neutral here! I don't know, but I've wired my basement that way. I would not use any wire smaller than 12ga since compressors tend to pull a lot of inrush current, especially when cold. I actually have an incomplete 10ga 20A wired circuit in my garage for a future dedicated compressor/car charging/gutter ice melt type things because I've had such bad luck with garage compressors blowing circuits on startup.

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I have this little jewel of a compressor in my garage: https://m.harborfreight.com/8-gal-2-hp-125-psi-oil-lube-air-compressor-68740.html

A basic 2 HP, 110 volt, ..........

 

Question for electricians: would it be OK to wire a light switch to the compressors dedicated outlet to turn it off/on?

 

 

Sure as long as the switch is rated for the load (2HP motor @ 110v) & the associated wiring/installation is to code.

NOTE: I'm not an electrician so take this advise with a grain of sand.

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Also, not an electrician......but I'd do it.

 

I always hate forgetting to turn my compressor off. I swear it never decides to cycle at 2pm, its gotta be 2am. The biggest PITA with mine is that I had my breaker panel replaced this past summer and now it trips the breaker every time it attempts to cycle on the first time. Once the piston is broken loose, it will cycle fine while I'm using it. The fun part is that it is on the same circuit as our large freezer in the garage. So if I forget, it will kick on in the middle of the night, trip the breaker, and begin to thaw out the freezer.....awesome. They really shouldn't be on the same circuit, but it was never an issue with the old panel......which is honestly part of the reason it was replaced in first place (google Federal Pacific if you are interested or have one of their panels). Anyway, my current use pattern is now, plug in the compressor, flip the switch, go reset the breaker, use the compressor, flip the switch off, and then unplug it. I'll most likely forget one of these days, lose a freezer full of food, then I'll wire in that dedicated circuit that it should have.

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  • 3 weeks later...

Bingo! Perfect idea!! Plug the compressor into a TIMER!

 

But not this type:

 

Intermatic-timer-001-450-S.jpg

 

The compressor is always "turned on" -- i.e. the unloader switch is always ON. If the air pressure in the system drops below X[PSI], the motor will cycle on. And since there are leaks in my airline, the darn compressor would automatically turn on at Y[time of day] EVERYDAY with this type of timer. Not good.

 

But I remembered that whenever I stay at the finer hotels [Motel 6], I always take advantage of their hot tubs to bubble my troubles away. There is a wind-up timer nearby that turns on the bubble jets for up to 30 minutes-- just choose how long you want:

 

gray-intermatic-timers-ff60mc-64_1000-S.jpg

 

The compressor is wired to its own outlet branch. So I will simply get one of these jewels that can handle a 2 HP motor, and wire it in-line.

 

Whenever I need air, I just wind it up, fill my tyres, and forget it. If I need more air, just drop in another nickle.

 

Problem solved.

 

Thanks all.

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Bud -

I see your switch is rated 1 HP while the compressor runs at 2. I'd be interested to know how significant is the difference.

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Ya know Lee, since it can take 20 amps and it only takes 14, I'm not sure. But I wouldn't be afraid to try it. After all, what's the worst that can happen? Breaker trips??????

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Ya know Lee, since it can take 20 amps and it only takes 14, I'm not sure. But I wouldn't be afraid to try it. After all, what's the worst that can happen? Breaker trips??????

 

Sorry to single you out Bud but thought processing like this is why codes exist.

 

When a motor starts it draws LRA (Locked Rotor Amperage) until it gets up to speed.

LRA is approx 600% of FLA (Full Load Amperage).

14x6=84 amps.

 

That's why I seriously doubt a spring wound in the wall timer is made to handle the 2HP@120V load.

 

These devices are designed to handle three types of loads, Resistive, Tungsten, & Inductive.

Each of the three loads has different electrical characteristics that are factored into the maximum allowed rating of such a device.

 

Ratings

 

Resistive:

20 Amp, 125 VAC, 50/60 Hz

10 Amp, 250 VAC, 50/60 Hz

10 Amp, 277 VAC, 50/60 Hz

 

Tungsten:

7 Amp, 125 VAC

 

Motor:

1 HP, 120 VAC, 50/60 Hz

2 HP, 240 VAC, 50/60 Hz

 

As far as your question of "what's the worst that can happen?"

A lot more harm then tripping a cuircuit breaker.

 

Again, there's a good reason why we have codes.

 

 

 

 

Edited by ESokoloff
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No problem Eric. Obviously you know a lot more about this issue than I do. I just a country boy from Southern Illinois so you can't always depend on what I say to be accurate. :wave:

 

In the interest of continuing my electrical education, how can a wall outlet wired to a 20 amp circuit run with a switch handle the load and the timer can not? Inquiring minds want to know.

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No problem Eric. Obviously you know a lot more about this issue than I do. I just a country boy from Southern Illinois so you can't always depend on what I say to be accurate. :wave:

 

In the interest of continuing my electrical education, how can a wall outlet wired to a 20 amp circuit run with a switch handle the load and the timer can not? Inquiring minds want to know.

 

 

zactly,...as I said, I'm not a code follower and in this application, the rarity of use would allow, to me, for the mitigation of any risks involved. If the switch blew, I'd get a new one, if anything further happened, I'm well insured ;)

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No problem Eric. Obviously you know a lot more about this issue than I do. I just a country boy from Southern Illinois so you can't always depend on what I say to be accurate. :wave:

 

In the interest of continuing my electrical education, how can a wall outlet wired to a 20 amp circuit run with a switch handle the load and the timer can not? Inquiring minds want to know.

 

 

zactly,...as I said, I'm not a code follower and in this application, the rarity of use would allow, to me, for the mitigation of any risks involved. If the switch blew, I'd get a new one, if anything further happened, I'm well insured ;)

 

Ignorance is bliss, but, once informed, it is just ignorance.

 

A friend of mine in the insurance business says that insurance companies are using social media to gather information in some cases where there is a question of policy holders culpability in a loss.

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No problem Eric. Obviously you know a lot more about this issue than I do. I just a country boy from Southern Illinois so you can't always depend on what I say to be accurate. :wave:

Bud, I'm sure you've forgotten hundreds of times more of your profession then I'll ever know.

 

I'm not an electriction by trade but being in the HVAC trade I've become a Jack of all trades out of nessesity.

 

 

In the interest of continuing my electrical education, how can a wall outlet wired to a 20 amp circuit run with a switch handle the load and the timer can not? Inquiring minds want to know.

Apples vs Oranges.

 

If a switch is rated for 1hp@120v then it will be rated for 20a resistive load.

If a switch is rated for 2hp@120v then it will be rated for 30amp resistive load.

 

Resistive loads (incandescent lights, strip heaters) do not have rotors & thus no LRA when the switch contacts close.

 

As to why there are no in the wall spring wound timers with a 2hp@120v load rating I would have to guess that there is not enough demand but again, that's just a guess.

 

 

To the OP, how about a 2hp/30a@120v rated switch that has a pilot indicator light the eliminates when the contacts are closed (switched on)?

see page 12 of 36

Also consider plugging in to the switched socket, a radio or perhaps a device that will make noise after a pre determined time to remind you to turn off the switch?

 

 

Edited by ESokoloff
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No problem Eric. Obviously you know a lot more about this issue than I do. I just a country boy from Southern Illinois so you can't always depend on what I say to be accurate. :wave:

 

In the interest of continuing my electrical education, how can a wall outlet wired to a 20 amp circuit run with a switch handle the load and the timer can not? Inquiring minds want to know.

 

 

zactly,...as I said, I'm not a code follower and in this application, the rarity of use would allow, to me, for the mitigation of any risks involved. If the switch blew, I'd get a new one, if anything further happened, I'm well insured ;)

 

Ignorance is bliss, but, once informed, it is just ignorance.

 

A friend of mine in the insurance business says that insurance companies are using social media to gather information in some cases where there is a question of policy holders culpability in a loss.

 

Again, I'll mitigate the risks compared to the requirements. No addition to my house has ever been inspected nor permitted. I just completed a bathroom remodel (complete gut job) and a basement bathroom addition (from scratch). My previous house was completely remodeled in every room, no inspections, no permits and sold just fine with no issues. We even threw in a wood stove from scratch, not inspected/permitted.

 

Ignorance by definition is simply lacking of information/knowledge. I'm not ignorant of the requirements/information/knowledge, I just choose to ignore them at times.

 

 

 

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zactly,...as I said, I'm not a code follower and in this application, the rarity of use would allow, to me, for the mitigation of any risks involved. If the switch blew, I'd get a new one, if anything further happened, I'm well insured ;)

 

 

Have you ever placed a claim on your homeowners insurance?

 

I have & there was a very thorough investigation into the cause of the incident including the confiscation of the item that caused it.

Fortinitly I was not at fault & the claim was paid.

 

Insurance company's don't stay in business handing out money that they don't have to.

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Thanks Eric for the explanation. I'm still not sure if you answered my question as to how that 2 HP compressor can work with a 20 amp wall switch but won't work with a 20 amp timer. The compressor has the same LRA plugged into a wall outlet as it would plugged into a timer. I must be missing something.

 

I have a woodworking shop in my basement. I know that when I start up my table saw, 120V, that it takes a while to come up to speed. For some reason, I thought there were some capacitors involved somewhere along the line that helped with the starting load, but I may be mistaken. I know my geothermal system is 220 V. 11 degrees now with wind chill of -11. Resistance backup has not come on yet so I guess the system was properly sized. There are three 750 loops in our buried in our back yard. When I spoke to the dealer, I told him I wanted the system to be able to bring the house temp down to 60 degrees when it was 100 degrees outside. We have a very well insulated house which helps a lot. I've never turned it down to 60 in the summer time, but it is usually set for 72.

 

 

 

 

 

 

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zactly,...as I said, I'm not a code follower and in this application, the rarity of use would allow, to me, for the mitigation of any risks involved. If the switch blew, I'd get a new one, if anything further happened, I'm well insured ;)

 

 

Have you ever placed a claim on your homeowners insurance?

 

I have & there was a very thorough investigation into the cause of the incident including the confiscation of the item that caused it.

Fortinitly I was not at fault & the claim was paid.

 

Insurance company's don't stay in business handing out money that they don't have to.

 

Yep, and I had no issues getting it paid. Two claims on the house, one from a leak over a year after an upstairs bathroom gut job. The other was clearly my fault, but they paid anyway (ran the jeep through the wall, garage to living room), homeowers paid for the repair to the house, auto claim was cancelled by us because no damage to the jeep.

 

 

 

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Thanks Eric for the explanation. I'm still not sure if you answered my question as to how that 2 HP compressor can work with a 20 amp wall switch but won't work with a 20 amp timer. The compressor has the same LRA plugged into a wall outlet as it would plugged into a timer. I must be missing something.

 

What your missing is that a switch rated @ 20amps @ 120v Resistive load is only rated for 1hp@120v Motor load.

If you want to switch a 2hp@120v Motor, the switch you need will be Resistaint Load rated @ 30amps@120v.

 

In other words you can not switch a 2hp @ 120v motor with a switch only resistive load rated @ 20a@120v. Such a switch doesn't/can't exist.

 

I have a woodworking shop in my basement. I know that when I start up my table saw, 120V, that it takes a while to come up to speed. For some reason, I thought there were some capacitors involved somewhere along the line that helped with the starting load, but I may be mistaken.

All single phase AC motors need a way to create an electrical imbalance in the winding(s) in order to cause the rotor to start to turn.

Likely your motor is a CSCR (Capacitor Start, Capacitor Run [look for two humps/capacitors]) or CSIR (Capacitor Start, Induction Run[Only one hump]).

 

 

I know my geothermal system is 220 V. 11 degrees now with wind chill of -11. Resistance backup has not come on yet so I guess the system was properly sized. There are three 750 loops in our buried in our back yard. When I spoke to the dealer, I told him I wanted the system to be able to bring the house temp down to 60 degrees when it was 100 degrees outside. We have a very well insulated house which helps a lot. I've never turned it down to 60 in the summer time, but it is usually set for 72.

 

For the most part inanimate objects aren't effected by wind chill/heat once they are at the same temperature as the ambient.

Furthermore Geothermal systems don't feel the ambient (air temperature) as the outdoor heat exchanger is generally located in a region that maintains a fairly constraint temperature year round.

 

72°?????!!!!

I'm MUCH to cheep for that :dopeslap:

77° is about the lowest I'll go in in the Simmer time (but perhaps the humidity is not as bad here?).

Edited by ESokoloff
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I'm wondering the rating of the switch on the HB compressor? From you explanation it would have to be a 30 amp Resistive load switch.

 

June, July and August are HHH. Hot, Hazy and Humid. My friend in Punta Gorda often pokes fun at me when we are at 95/95 temp/humidity and they are cooler and much less humid.

 

I have developed adult onset asthma which is triggered by exercise. I try not to be outside a lot in the summer unless on the bike.

 

Was Simmer time a pun or a typo. I think it is a great term for summer. :grin:

 

Riding season in the midwurst is a few weeks away, but I'm getting the itch for one more long ride. A few years back I rode to Nova Scotia, over three weeks of fun. Last year I told Nancy and most likely didn't have one more trip in me, but as I'm starting to return to feeling better, a trip out west or maybe to the Icefield Parkway seems to be attracting me in that direction. Other than a trip to Redmond for a MOA rally, I've not ridden in the PNW and never ridden in N. California so there is a lot from which to choose.

 

The house is currently 72, outside -1, wind chill -11. When you come in the house it feels warm. In the summer, when you come into the house, still set at 72, it feels cold. Nancy would love it warmer in the simmer.

 

Hope you are getting a chance to enjoy your balmy weather in sunny S Cal. I've been amusing my self with reading ride reports on ADV.

 

 

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No typo, just the truth.

Simmer kicks in after June Gloom (coastal fog) usualy by the first part of July.

Then comes Augggst followed by Sweatember & then sometime in October it's still warm by day but the nights cool off.

Novemburrrr is the start of the long awaited cool off.

We don't get much annual precipitation (12") as it's a desert.

For the most part run-off is not collected/stored so precipitation is of little benefit other then to reduce irrigation.

We steal.... um obtain our water from other areas.

 

 

I worked yesterday (@2.5xpay) and on my commute home along PCH I was reminded of how fortunate I am as the road was extra busy with many vehicals with out of state license plates.

Here were people spending their hard earned dollars just for the opertunity to share my commute :P

I took a side road up & over the hill (Santa Monica mountains) thus avoiding the worst of it (downtown Malibu).

 

 

Many fabulous roads to ride out this way but SoCal has a lot of shorter but more technical routes were as Central & NorCal will tend to have longer meandering routes (less development).

 

It's been dryer then a popcorn fart thus far here.

Yesterday (early AM) was the first sighting of dew (headlight reflecting off the sides of vehicles).

December & January are the coldest.

A few weeks back my TPM system indicated 27° on my morning commute.

That's almost too cold to be riding my non-faired duel purpuse Zero.

The wettest months are February & March.

I'm a year round rider so I'm not looking forward to that time.

 

-11°?

At work we have a walk-in freezer that will do that.

What's the big deal??? :dopeslap:

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-11°?

At work we have a walk-in freezer that will do that.

What's the big deal??? :dopeslap:

 

That's what I say, commute this morning for the hour ride to work was 7*,.......I sure do get the crazy-eyed looks during my inclement weather rides.

 

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