Pump Motor Causing Doorbell to Ring???

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Little Bill

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Tennessee NEC:2017
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Let me preface this with... I have not went to investigate nor did I witness any of the things that I was told happened.


I wired a swimming pool a month or so ago. The pool installers didn't have anything ready for me to run the equipment that I wired so all I know is the voltage to each item was correct and wired properly.
I got a call from the HO saying their doorbell started ringing one night with no one at the door. They said also their phone started ringing but with a strange ring. I don't know how many times this happened but somewhere along the line they said they noticed these things whenever the pool pump would come on.:huh:

Now, the pool equipment is powered from a subpanel that I set close to the equipment. The pool (sub)panel is fed from another subpanel that is in a barn about 85' from the pool. The barn subpanel is fed from the house main panel about 125' away.

So the doorbell and phone are in the house with no connection to the pool panel other than through the panel in the barn.

The HO couldn't tell me if the doorbell was wireless or hardwired and wasn't sure if the phone that was ringing was cordless or standard corded phone.

If the pump motor could be causing this, how would this happen and how could it be doing it so far away from the house.

Let me add that the pool pump is powered through a salt generator with a built-in timer. Not that it matters but the salt generator is also fed through a timer. I put the timer in because I wasn't told the salt system had it's own timer.
 

Jraef

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A lot of new pool pumps are coming with VFDs built-in, whether you know it or not. If so, a poorly shielded one could be spewing out a lot of RFI that could be picked up by a cordless phone or doorbell. I put in a wireless doorbell, because there never was one here and I didn't want to run the wires (lazy). It rang mysteriously for months, I was thinking a neighbor had the same one somewhere near by. Turned out to be the little VFD I wired up to my fountain in the back yard. I didn't worry about the wiring at all, violated my own rules. Turned out I was making a little radio station in my yard.
 

rlundsrud

Senior Member
Location
chicago, il, USA
So wrapping the house in tinfoil would shield it from the stray RF!!!!!



I lined my hat with tinfoil years ago........

MIT actually did a study on the efficacy of foil head gear to protect against EMF (by aliens or the governement, it was a pretty inclusive study). While the concept is sound, the implementation was found to be lacking. To effectively block those nasty aliens from reading your thoughts, you would need to completely enclose your head to create a proper Faraday cage. Given human anatomy, the attachment point for the head (ie. The neck) precludes properly enclosing the skull. It was actually found that the foil helped EMF to penetrate the users head. I also want to add that I find it very distasteful that no one knows how to properly accessorize their anti-alien wardrobe with a very nice aluminum foil tie, belt, shoes, or any other accoutrement. I mean really, you have to dress for success, and I feel that includes stopping my thoughts from being used by the government or any other entity (except Mike Holt of course).

My apologies for the little diatribe, just my two cents worth of foil.
 

Little Bill

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Staff member
Location
Tennessee NEC:2017
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Semi-Retired Electrician
A lot of new pool pumps are coming with VFDs built-in, whether you know it or not. If so, a poorly shielded one could be spewing out a lot of RFI that could be picked up by a cordless phone or doorbell. I put in a wireless doorbell, because there never was one here and I didn't want to run the wires (lazy). It rang mysteriously for months, I was thinking a neighbor had the same one somewhere near by. Turned out to be the little VFD I wired up to my fountain in the back yard. I didn't worry about the wiring at all, violated my own rules. Turned out I was making a little radio station in my yard.

I mentioned that the pump is powered through a salt generator, here is how it is wired.

The salt control box has two cords (SOW?) for line/load and a smaller control cable that goes to the salt module in the plumbing line. The power cords are too short to reach the pump so a junction box has to be used.

Junction box
Power in to the JB & connected to the cord for the line in
Power/load out cord connected to the new load conductors to the pump
The cords and the feed to the pump (THWN) are in liquid tight nonmetallic conduit

The control cord is not in the liquid tight, just the SOW cord.

So does any of this sound like RFI could be "escaping"? If so, how or what could be used to shield it?
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
I mentioned that the pump is powered through a salt generator, here is how it is wired.

The salt control box has two cords (SOW?) for line/load and a smaller control cable that goes to the salt module in the plumbing line. The power cords are too short to reach the pump so a junction box has to be used.

Junction box
Power in to the JB & connected to the cord for the line in
Power/load out cord connected to the new load conductors to the pump
The cords and the feed to the pump (THWN) are in liquid tight nonmetallic conduit

The control cord is not in the liquid tight, just the SOW cord.

So does any of this sound like RFI could be "escaping"? If so, how or what could be used to shield it?
Is the pump just a plain single phase motor or variable speed?

Even if not variable speed, it could be the salt chlorinator power supply. Either way, it's likely the SOW and the fact that there is no shielding. Steel conduit works, but gets nasty in pool environments. You can get shielded SO cord from people who sell VFD cable. It's more expensive. But this is exactly what it is for. Ground the shield at BOTH ends on an application like this.
 

Little Bill

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Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
Is the pump just a plain single phase motor or variable speed?

Even if not variable speed, it could be the salt chlorinator power supply. Either way, it's likely the SOW and the fact that there is no shielding. Steel conduit works, but gets nasty in pool environments. You can get shielded SO cord from people who sell VFD cable. It's more expensive. But this is exactly what it is for. Ground the shield at BOTH ends on an application like this.

The pump is probably a variable speed since it has a control keypad on it as well as being controlled via the salt control box. I've hooked up a few of these pumps with the salt system and they can either run independently of the salt system or with it.
The SO cord came factory installed so I don't think changing it would be an option since it likely would void the listing of the salt control unit.

Any suggestions for sleeving the existing SO cord?
 

Jraef

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Staff member
Location
San Francisco Bay Area, CA, USA
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Electrical Engineer
It might be shielded then. Double check your ground connections. Make sure everything is going to ground as early and often as possible. Generally the RFI is irrelevant and people often don't notice it even if it gets bad as ground connections deteriorate. But you have systems nearby that are sensitive to it.

If you can get to the VFD itself, you can try tweaking what's called the Carrier Frequency, which is the pulse rate of the transistors. Often times people set it high to make the motor quieter, but it creates more EMI/RFI. Lowering it is better for the drive and motor, plus it will change the RFI output. The motor will whine more (audibly) though.
 
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