I purchased my house used, in the outbuilding (about 300 feet from the main house) there is a Spring Controls Contactor Model J150CA300. It hums quite loudly, INCESSANTLY, ALWAYS, ALL THE TIME... and it's quite annoying.  I have taken it apart and cleaned up the contacts and no difference.  Plus last night is was getting louder then softer cycling about every 4 seconds and I could not relate the cycle to anything.

My question is what does it actually do and do I really need it?  In other words can I remove/bypass it and get rid of the noise.

To clarify: as the power comes out of the wall, it first goes through the Contactor then to the FB, there are no other wires coming from the contactor box other than the ones going to the FB.

In the outbuilding I use very little electricity (lights, battery chargers etc...  once in a while I use the car lift and it's 220v).   The previous owner used the outbuilding as a mechanics shop and had a compressor and bodywork equipment.  I only have 2 phase, not 3.

I do not understand what it does and if I actually need it.   Thank you!https://www.instagram.com/p/CYpCbmHpFHA/?utm_medium=copy_link

So... there is a breaker leading to the contactor and another 80 AMP breaker for the 220 lines,  both breakers are at the house but outside, so not an easy 'flip a switch' to cut power.  Based upon the replies, and since the outbuilding is still on a breaker, I do believe I'll bypass the contactor and live a quiet life, thanks for all the help and replies.  I will check up on this thread to see if there are additional replies.

Would like some pics

What does the contactor power?  Its just a big relay to turn power on to something else, not per say part of your building wiring.

AC unit?  The big air compressor?

Turn off the breaker for it, see what doesn't work.

First off, a contactor is just a heavy duty relay.  That is, it allows a high powered device to be turned on and off with a much lower powered device (e.g., switch).

Without more information it's impossible for us to tell you whether or not you still need it.  You'll have to trace the wires.  Undoubtedly one set will go to your breaker panel, probably through a switch.  The other set should lead to a heavy duty piece of equipment.

Let us know what you find.

Anyt inductor like that will exhibit magnetostriction, or mechanical hum. Is it securely fastened and tightend down to whatever it is mounted on? Is the mount loose? These would all be things to check before replacing it.

Depending on the age of the contactor the coil could be getting tired.  Pics might help.

I'll see if I can get some pictures up, in the meantime I'll give additional details.

The power supply lines come out of the wall, into the contactor box, and then into the fuse box.  Of the 3 power lines, 2 are run through the contactor to the fuse box (FB), the 3rd line bypasses the contactor and goes to the FB.  

A thick green wire also exits the wall and runs to the FB (ground to the main box?).  1white and 1 red wire exit the wall and are connected to the top backside of the contactor.

There is a breaker in the main house that controls the power to the contactor.

There are 2 AC units in the outbuilding but seem to have nothing to do with the contactor.  The only wires leading into the contactor come from the house, the only wires leading out go to the FB

This. It more than likely ran a large air compressor but could be what runs your car lift.

It is not connected to any breakers, it is located between the main house and the outbuilding breaker box.  I assume if it controlled anything it would be wired to the FB between the controlled item and the FB.

The PO of the property rigged a lot of shit in the worst way, eg: he ran 220 to a 110 outlet.

Still working on getting an Instagram account

You can use imgur to upload some pics. It has to have a breaker somewhere. Crazy if not in the unit where it is. If it is humming then it sounds like the coil is energized/latched so it is running something. How did you kill the power to clean it? Disconnect the switch part (Of course after you kill the power) (A1 and A2 on top I think or similar, dl  a manual on yours) and see what turns off.

I've seen a few garages that used a contactor for lighting.  I believe the thought was you could run all the lights through one circuit but not sure.

I was able to link to instragram.

If I am thinking through correctly, there is a breaker in the house that controls the contactor and therefore the contactor supplies power to the outbuilding breaker box, and then to the entire building.

I can cut power to the outbuilding by flipping a breaker in the house, I now assume I am cutting power to the contactor and therefore the entire building.

I suppose this goes back to my original question, can I bypass the contactor and get rid of the noise or is that a big no-no in an electricians world.

I have NO IDEA what they were doing. If that is just some sort of junction to feed power to the shed then I don't get it. If that is all it is doing then, yes you can replace it with the proper sized breaker in that box. That white and red wire on top is what is latching it so if you kill power to that unit then disconnect it then turn power back on you will know for sure what it is powering be it the whole shed or just the lift. Like I mentioned earlier. Normally that is used to turn a motor on and off like on an air compressor or pump or similar.

Attached File

And report back.

The breaker on the house, when flipped off, kills power to the entire outbuilding.  I assume that instead of using the contactor to control a lift, compressor or something, they used it to power the entire building.

The cure for the buzz is a solid state contactor.

Do you know what the red wire from the contactor goes to?

A picture of your fuse box would help.

To be up to code any detached garage, out building, shed needs a means of disconnect. That could be done through a breaker, switch, or some other means. The breaker on your house would not count.

Based on the current model I have, could you recommend one?

Ideally the contactor would be controlled by a switch.  The smaller red and white wires in your picture are the wires that control the contactor, I.E. turn it on and off.  If it's 120v, it's probably just a switch to turn whatever the contactor supplies on and off.  If it's 24v, it may be the control coming from something else.   You looked at the contacts, which is the first thing.  Next look for what supplies the power to the coil.  Check to see that the voltage is correct and constant.  Unfortunately digital meters are poor for this because they tend to "smooth" out the readings and you may not see an intermittent voltage drop. It may be something simple as a loose wire in a wire nut either there or from wherever the coil is fed.  You need to find what controls it.

That said, coils do chatter when they get old/weak.  You can buy a new contactor, but make sure the ratings for the contacts and coil match.

All AC coils hum to a certain extent because they use AC (alternating current) there is a natural point 60 times a minute when your voltage is effectively zero.  Yours is a cheaper one and it just may be that its hum is going to be louder. I would think about just replacing it with a quality A-B or equivalent contactor.

Follow the red wire out of the contactor box. May go to a switch possibly by the door. Former owner may set it up so he could turn the switch off and kill the hole building instead of turning everything off by hand.

I am betting this.

If their is a breaker in the house, and a breaker box in the outbuilding, then just replace the contactor with a manual disconnect switch.

Seems like it's in place to kill power to the outbuilding with a switch for whatever reason. I'd remove it and connect the wires.

I like this idea and may incorporate it, but the red wire comes from the house and only goes to the contactor, but it would be east to tap into it and add a switch.

My guess is the contactor is in place so he could cut power to the building from the house fuse box.

But one of these. Or, why even bother?

Yep. Looks like he rigged up a contactor to be a remote switch for the entire building.

You could definitely add a switch into the circuit if you wanted.

so he ain't got to listen to that damn constant humming ALL THE TIME

OP, is there a light switch in your house that doesn't seem to do anything? (Besides kill the power to your shed)

We have a few 'mystery' switches, but they don't control the out building.  I think they are left over from separate light/ceiling fan switches.

The red and white wires originate at the house breaker box and terminate into the contactor, then the contactor feeds the outbuilding breaker box, thus feeding the entire building.  I find it kind of odd 2 breakers right next to each other will both cut power to the outbuilding, neither are handy as they are on the outside of the house.

what size are those breakers?

More pics here: https://www.ebay.com/p/26037209342

Agree with the above, there is likely another circuit tied to a switch somewhere that is used to control power to the outbuilding, as that is better than flipping a breaker on/off.

You can likely replace it with a disconnect, just one rated for however many amps are going to the outbuilding.

80 amp for the power lines leading to the building, 20 amp for the breaker that controls the contactor.

I tottaly understand and get the idea of shutting down the power to the building via contactor, but on the other hand, there go the outside floodlights, motion cameras, battery chargers etc....

Maybe it was installed w/ the intention of having a whole building shutoff but never implemented?

I have seen those contactors on the line side of single to three phase converters to avoid voltage spikes from the phase converter backfeeding the single phase