Reverse polarity switch

[Paulypaul]

We've got a reverse polarity switch fitted in our Pilote. It's never had any issues before, but when we returned home and plugged in the ehu lead yesterday, the switch is making a high pitched noise.

Its not showing a red light so it's not a reverse polarity alarm, but I just need to sort it cause when we do go on a site with ehu the high pitched noise will drive us mad.

Any ideas would be appreciated.

Thanks

 

[Clarky]

No idea as I don’t know the Pilote but a couple of thoughts.
Are the terminals of the hookup cable OK ie. no leaks to earth?
Is there an inverter connected to the mains circuit in the van which has been left switched on?

Richard.

 

[Paulypaul]

That's a good point, I'll try another ehu lead and see. Thanks

 

[Bessy765]

If you have a circuit tester, check the lead especially the earth for continuity. Further check would be although a bit of a faf around would be to have a short lead clearly marked with the live and neutral reversed the type I carry if I am on a site with the wires reversed. Plug that in and see if either the red light comes on or the noise continues indicating a fault in the warning system.

 

[Pausim]

We've got a reverse polarity switch fitted in our Pilote.

With Pilote being a continental construction it is probably safe with reverse polarity. I believe it is only UK sockets with single pole switching that are vulnerable to reverse polarity safety issues. I just assume that either wire might be live, or both when using an inverter.

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[pappajohn]

Or just bypass it.
Reverse polarity is harmless unless you have your hands and tools inside an appliance repairing it without unplugging first.

 

[Paulypaul]

I've just swapped leads and it's just as it was before, the green light is illuminated to denote safe, but there's a high pitched buzzing still? That's going to sound like an army of crickets at night so I need to get it sorted.

 

[Paulypaul]

Is there an inverter connected to the mains circuit in the van which has been left switched on?

No we don't have one fitted

 

[Paulypaul]

The buzzing has stopped on its own accord? Wonder whether it was the battery charger drawing more power to stabilise the batteries? Thanks all for your input though.

 

[Raul]

I would say to check for loose connections. Humming buzz can go away when low load and return on high load. Make sure there is no terminal screws, connection loose, it can happen with fatigue and vibration.

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[Paulypaul]

I'll do that, thanks. But, the van had just sat there with nothing on, apart from the battery charger? Hence my theory about the batteries being stabilised... .although I don't really know what I'm talking about and it's just a guess

 

[autorouter]

We've got a reverse polarity switch fitted in our Pilote. It's never had any issues before, but when we returned home and plugged in the ehu lead yesterday, the switch is making a high pitched noise.

Its not showing a red light so it's not a reverse polarity alarm,

When you say it's a switch, do you mean it's an actual manual switch that you use to correct the polarity if it's reversed? Or is it an automatic switchover that corrects whenever it detects reverse polarity?

Does the high pitched noise sound like a warning buzzer, or more like a fault (buzzing relay, arcing loose connection)?

Was this detector fitted from new, or is it an after-market add-on? Does it have a make and model number, or is it part of a distribution/fusebox or maybe the display?

 

[Paulypaul]

Yes, it's a physical switch

 

[bigtwin]

I suspect that there’s a relay inside that box and that’s what’s buzzing.

Might be worth checking with a view to obtaining a replacement relay (likely to be only a few pounds).

Ian

 

[Richard n Ann]

That looks like a 16 amp or 20 amp switch so it might not have a relay, could just be this inside and maybe a piezo buzzer?

Open it up

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[Paulypaul]

Thanks Ian, at present the box is silent with the green light illuminated. When I first plugged in the ehu lead the green light was on but there was a buzzing, not like a short out or alarm, but very similar to when you connect a battery charger and it starts to stabilise the battery before it continues to charge it? After a few hours the switch went silent.

I'll isolate the power and take the cover off, is the relay similar to a 12v relay in appearance?

 

[Paulypaul]

That looks like a 16 amp or 20 amp switch so it might not have a relay, could just be this inside and maybe a piezo buzzer?

View attachment 508622

Open it up

Sorry, didn't see your post when I was replying to Ian. If it is as you suggest, would that mean the switch is faulty?

 

[Richard n Ann]

Sorry, didn't see your post when I was replying to Ian. If it is as you suggest, would that mean the switch is faulty?

Usually when that type of switch fails you can feel it doesn't feel right, either physically sticks or goes loose.

Could have been arcing though let's see inside

 

[Richard n Ann]

A relay to switch that would be expensive.

 

[Paulypaul]

Mmm, I'm just going out to have a look inside the switch housing. I've googled the price of a new switch which are about £48.?

I'll post a picture of the inside in a bit.

Thanks

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[Paulypaul]

This is what is inside Richard:

 

[autorouter]

So it looks like it's a manual switch wired exactly as in Richard n Ann's diagram. There's an additional buzzer (the round white thing) that is probably wired in parallel with the red light.

The question is, is it a fault in the switch box, or is there a mains problem? Does the red light actually work - as in, if you deliberately switch it to reverse polarity, does the red light come on or has it failed?

Maybe there's a fault inside that black square electronics module, so that the buzzer is/was turning on when it should have been off. Maybe the buzzer is off because it has failed. Does it sound when you deliberately switch to reverse polarity?

 

[Paulypaul]

If I deliberately engage the switch the red light does illuminate and the buzzer sounds. When I return the switch to normal the green light illuminates and the buzzer goes off? I know it looks like its working but I'm just baffled at the initial buzzing when I first hooked up?

 

[autorouter]

There is probably some electronic logic circuit inside that black square electronics module, and maybe some spurious voltage spike triggered it. If it happens again you could try unplugging the ehu for a few seconds to see if it resets.

 

[Paulypaul]

Thank you all for the advice, much appreciated.

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