Vax rapide carpet cleaner tripping RCD

rockchick113

Having a clear out of my daughters, we came across a vax rapide carpet cleaner. Having cleaned it up of all the dust and years of grime. We come to plug in for a test. It’s a two switch cleaner, one for  the cleaner and one for  the brush roller. First switch all ok, then came to switch on the roller, RCD tripped. Having then taken apart the handle to check the switch then the roller motor. I managed to get a new switch from ebay, replaced today. But still tripping the RCD on switching on the rollers. I’ve checked the motor and it turns freely with my fingers. I’ve spent all day checking the wiring, but all is ok. Even though the roller motor turns freely, could it still be the problem ? 

So far it’s cost me £10 on a new switch, but a motor is another £20 on ebay. 

Or should I just give up. 

Thanks for any help. 

grumbler

RCD is tripped by electric current leaking to 'earth'.

If a switch doesn't have any visible contact with earthed metal parts and isn't wet, it cannot trip RCD. The same applies to the motor.

rockchick113

grumbler said:

RCD is tripped by electric current leaking to 'earth'.

If a switch doesn't have any visible contact with earthed metal parts and isn't wet, it cannot trip RCD. The same applies to the motor.

It’s certainly not wet, so that’s not the problem. And I can’t find any break in wires. With it only happening when I turn on the brush motor, I followed the wires back to the switch and all ok. 

Eldi_Dos

Have you checked inside plug that there has not been a build up of moisture from the time it has been stored?

grumbler

Eldi_Dos said:

Have you checked inside plug that there has not been a build up of moisture from the time it has been stored?

If it was the plug, then it'd trip the RCD every time you plug it in. As it's some switch, then it's something after the switch.

The motor is the most likely suspect if it's earthed.

rockchick113

grumbler said:

Eldi_Dos said:

Have you checked inside plug that there has not been a build up of moisture from the time it has been stored?

If it was the plug, then it'd trip the RCD every time you plug it in. As it's some switch, then it's something after the switch.

The motor is the most likely suspect if it's earthed.

Grumbler if I get another motor do you think that should do the trick ? Or is there a way of testing the motor out of the machine, it’s only two wires on spade fitting. 

grumbler

rockchick113 said:

grumbler said:

Eldi_Dos said:

Have you checked inside plug that there has not been a build up of moisture from the time it has been stored?

If it was the plug, then it'd trip the RCD every time you plug it in. As it's some switch, then it's something after the switch.

The motor is the most likely suspect if it's earthed.

Grumbler if I get another motor do you think that should do the trick ?

I wouldn't hazard a guess.

Or is there a way of testing the motor out of the machine, it’s only two wires on spade fitting.

Again, if there are only two wires and dry plastic around the motor, nothing connecting it to the earth wire, it cannot trip RCD. What is the earth wire connected to?

If there are some metal parts connecting the motor to the earth wire, then, if you have a tester, after disconnecting the 'line' and 'neutral' wires you can measure the resistance between either terminal of the motor and the earth. It has to be very high. If the tripping current is, say, 30mA, then the resistance has to be considerably  higher than 230V/30mA = 7kOm.

However, the result you get with the low voltage of the tester can be very different from the one with a higher voltage. Only low resistance proves the fault; high resistance is inconclusive.

ETA: are you sure it's RCD, not MCB or RCBO?

The latter two can be tripped by high current (short circuit), not by a leaking small current to earth.

rockchick113

grumbler said:

rockchick113 said:

grumbler said:

Eldi_Dos said:

Have you checked inside plug that there has not been a build up of moisture from the time it has been stored?

If it was the plug, then it'd trip the RCD every time you plug it in. As it's some switch, then it's something after the switch.

The motor is the most likely suspect if it's earthed.

Grumbler if I get another motor do you think that should do the trick ?

I wouldn't hazard a guess.

Or is there a way of testing the motor out of the machine, it’s only two wires on spade fitting.

Again, if there are only two wires and dry plastic around the motor, nothing connecting it to the earth wire, it cannot trip RCD. What is the earth wire connected to?

If there are some metal parts connecting the motor to the earth wire, then, if you have a tester, after disconnecting the 'line' and 'neutral' wires you can measure the resistance between either terminal of the motor and the earth. It has to be very high. If the tripping current is, say, 30mA, then the resistance has to be considerably  higher than 230V/30mA = 7kOm.

However, the result you get with the low voltage of the tester can be very different from the one with a higher voltage. Only low resistance proves the fault; high resistance is inconclusive.

ETA: are you sure it's RCD, not MCB or RCBO?

The latter two can be tripped by high current (short circuit), not by a leaking small current to earth.

I think it could be a short circuit. I’m tempted to buy the motor but that’s £20 wasted if it still trips.

I don’t like being beaten and having to throw something away if it can be fixed. 

Thanks for all your advice 

Grizzlebeard

If you have a multimeter check for open circuit between the big earth pin in mains plug and other two pins. Should be open circuit(infinity) for all switch positions.

Disconnect the motor and insulate the spades to make safe. Then see if it still trips when switched on. If it does it's not the motor but somewhere in the wiring.

Very rare, but suppressor capacitors on (or in) the motor occasionally fail short.

Rodders53

My Vax Rapide is a double insulated machine - so no earth connection to it.  The rating plate on rear (of handle) will have a square within a square (the symbol for double insulated) if it's the same as mine.

OP needs to clarify what is tripping.  Photo of that trip?

But random parts replacement is probably a losing battle and they need a good multimeter at least, and the knowledge to use one to diagnose the fault.  Especially as a switch is the least likely item to cause a trip like this.

rockchick113

Thanks all for advice. I will consign it to the tip. Hopefully resell the switch back on ebay.