I need a time-delay Square D breaker for a new air compressor.

SITUATION I have a 200 Amp electrical panel in my home. It's says QO Combination Load Center Cat QO-40M Ser T4.

I built a garage a few years ago and brought a 12/3 wire to it which I had connected to a 20 Amp SquareD circuit breaker I bought.

I have the following in my garage

- garage door opener, 8 x 100Watt light bulbs, Table saw, Old Shop Vac, etc...

I just bought a Delta Air Compressor but it popped my 20Amp breaker. Nothing else in the garage was on, except maybe the 60Watt light bulb in the garage door opener.

So then I read in the compressor manual where I found the following specifications:

- Voltage-Single Phase 120V/60Hz/1Ph

- Minimum Branch Circuit Requirement 15 amps

- Fuse Type Time Delay (circuit breaker is preffered)

QUESTION How can I differentiate from a reqular SquareD circuit breaker and a Time Delay SquareD circuit breaker. There doesn't appear to be any indications on the breaker itself.

Thanks for any and all information.

G Doucet

Reply to
Guy Doucet
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Sounds like you should take a look at the motor amp rating and horsepower on that new compressor of yours.

A compressor motor will draw up to three times its rated running amperage to start up. Could be up to 45 amps in your case depending on the motor horsepower.

Have never heard of a "time-delay" circuit breaker???

Fred

Reply to
Fred

"Guy Doucet" wrote

Always check the specks before buying. I am a mech. engineer, not an electrician, but I think all breakers are time delay. Some are GFCI, or arc fault, leading to other things to check for.You do not give much information as to the event, but it sounds to me like a wiring, or compressor problem not a breaker problem. How far does the wire run from the main panel to the garage (voltage drops under load at the outlet)? Is this a plug in compressor or a hard wired one? Did the motor start up then blow the breaker, or did the breaker trip without the motor turning? With the compressor disconnected from the power and the air lines open, assuming it is accessible can you turn the motor by hand? Did you remove all the shipping materials?

Reply to
Stephen B.

About how long is the run from the breaker panel to the garage?

If all 8 light bulbs are on then you probably will pop the breaker if you try to run the compressor.

The terseness of the label is a bit confusing. "Time delay" refers to the fuse type, not the breaker type. A better way to put it would be:

Reply to
mroberds

indications

- The circuit breaker popped as soon as I turned on the power switch of the compressor - the compressor itself didn't come on at all.

- It's a plug in compressor, it's not hard wired. I plugged it into the outlet in my garage.

- The specifications in the manual says that I need a time-delay fuse but a circuit breaker would be better.

- "Perhaps circuit breakers are all time delay".

Anyway, I reset the breaker and decideed to try it again - and it actually works now, HURRAAAAYYYYY!!! :-)

Perhaps the compressor popped the breaker the first time because it was new and had not been turned on before???

Besides that, the 12/3 wire that I have running to the garage is about 40 feet long. I think I'm gonna try to get 10/3 or bigger, and perhaps even I'll try to install a sub electric panel in the garage!

Thanks for all.

Guy Doucet

Reply to
Guy Doucet

- The circuit breaker popped as soon as I turned on the power switch of the compressor - the compressor itself didn't come on at all.

- It's a plug in compressor, it's not hard wired. I plugged it into the outlet in my garage.

- The specifications in the manual says that I need a time-delay fuse but a circuit breaker would be better.

- "Perhaps circuit breakers are all time delay".

Anyway, I reset the breaker and decideed to try it again - and it actually works now, HURRAAAAYYYYY!!! :-)

Perhaps the compressor popped the breaker the first time because it was new and had not been turned on before???

Besides that, the 12/3 wire that I have running to the garage is about 40 feet long. I think I'm gonna try to get 10/3 or bigger, and perhaps even I'll try to install a sub electric panel in the garage!

Thanks for all.

Guy Doucet

Reply to
Guy Doucet

| QUESTION | How can I differentiate from a reqular SquareD circuit breaker and a Time | Delay SquareD circuit breaker. There doesn't appear to be any indications on | the breaker itself.

The standard breakers have a combination magnetic trip and thermal trip. The magnetic trip is generally set at a few times the breaker rating. That should trip in the case of a short circuit. The thermal trip would be close to accurate, and this is the time delay part.

Apparently the starting current for your compressor is pulling quite a lot of current. How fast does your breaker trip? If immediate, then it is the magentic element doing the job. Increasing the breaker rating would not generally help because that element is usually around the same rating for breaker from 15 to 60 amps.

If there is any delay from compressor start to breaker trip, it could be that the compressor is pulling locked rotor amps for too long of a period. Maybe it needs some appropriate maintainance, lubrication, etc.

Breakers that can be adjusted for magnetic trip point and time delay do exist, but they are expensive (well over $1000).

Reply to
phil-news-nospam

They're standard in Europe. Breakers are rated Type B, Type C, or Type D. Type B will allow through 3-5 times the rating for a short time without tripping, type C is

5-10 times, and type D is 10-50 times.

Type B is the standard breaker used in the home. Type C is normally used for things like aircon and other large motors. Type D is specialist use and not found in the home. Square D manufacture this range for Europe (might not go up to Type D -- generally only industrial breaker ranges do).

(In the UK, we used to have Type 1, 2, 3, and 4 with similar meanings, but have switched over to the common EU types now.)

Reply to
Andrew Gabriel

Update the wiring to your garage. Run a dedicated line for the compressor for starters. Or put a sub panel in the garage. Or call a qualified electrician before your house burns down.

| QUESTION | How can I differentiate from a reqular SquareD circuit breaker and a Time | Delay SquareD circuit breaker. There doesn't appear to be any indications on | the breaker itself.

The standard breakers have a combination magnetic trip and thermal trip. The magnetic trip is generally set at a few times the breaker rating. That should trip in the case of a short circuit. The thermal trip would be close to accurate, and this is the time delay part.

Apparently the starting current for your compressor is pulling quite a lot of current. How fast does your breaker trip? If immediate, then it is the magentic element doing the job. Increasing the breaker rating would not generally help because that element is usually around the same rating for breaker from 15 to 60 amps.

If there is any delay from compressor start to breaker trip, it could be that the compressor is pulling locked rotor amps for too long of a period. Maybe it needs some appropriate maintainance, lubrication, etc.

Breakers that can be adjusted for magnetic trip point and time delay do exist, but they are expensive (well over $1000).

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Reply to
Brian

You need a QO-HM breaker ("high magnetic"). They are designed to withstand much higher inrush current than the standard QO, and they are physically interchangeable. Available in 15 or 20 amp rating. You probably won't find them at the local home center store, however.

Ben Miller

Reply to
Ben Miller

That was likely your problem. 40' of 12/3 cord might have just enough voltage drop to cause the breaker to trip IF the utility voltage happened to already be a bit low that moment. Probably the 2nd time you tried it, the utility line was back to normal and it worked without tripping the breaker. If I were you, I would do exactly as you indicated; buy a 10/3 cordset if you need to go that far.

And that other post was correct. You were taken in by the poor wording of that label. "Time Delay" was refering to only the fuse, all circuit breakers are "time delay" by nature of their design.

Reply to
Bob

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