Washing machine and new consumer unit

[david3456]

We have just switched on the washing machine for the first time after a CU change. Needless to say, it trips the RCD.

We then discover this in the machine instructions:

I know there are different ways of fault detection but I can't find any reference to this symbol. What is this type and is there a simple solution to the problem?

 

[stem]

Earth-leakage circuit breakers were superseded by RCD's about 20 or more years ago, so if your washing machine is really that old (as opposed to just the text in the instructions) then it's probably time to change it. Otherwise there is a leakage of current to earth somewhere inside your washing machine, there could be lots of causes from a faulty component to a water leak causing a short circuit somewhere, a good domestic appliance engineer with the correct testing equipment should be able to diagnose it for you. If you know that it trips at a certain point in the cycle such as when the pump or motor starts, this can help diagnosis.

 

[JohnW2]

...I can't find any reference to this symbol. What is this type ...

I believe that is the symbol for a "Type A" RCD - i.e. one that will react to pulsating DC currents as well as AC currents.

Kind Regards, John

 

[david3456]

Earth-leakage circuit breakers were superseded by RCD's about 20 or more years ago, so if your washing machine is really that old (as opposed to just the text in the instructions) then it's probably time to change it.

It's about 2005-ish. It ran for about 5 minutes until the drum filled. Perhaps the heater has become electrically porous.

I believe that is the symbol for a "Type A" RCD - i.e. one that will react to pulsating DC currents as well as AC currents.

OK, found it now. So it appears it should more sensitive than the one in the CU, it's not that the CU is detecting something a type A would not.

 

[DetlefSchmitz]

It could still be a fault with the new CU wiring (neutral in wrong bar).

 

[Risteard]

Earth-leakage circuit breakers were superseded by RCD's about 20 or more years ago

That's not correct. An RCD is an earth-leakage circuit breaker. The use of VOELCB (voltage operated) has been discontinued but COELCB (current operated) are now called RCDs.

 

[JohnW2]

It could still be a fault with the new CU wiring (neutral in wrong bar).

Possibly - but very unlikely if, as we've been told, the WM runs for ~5 mins before the RCD trips. If the neutral were in the wrong bar at the CU, one would expect the RCD to trip immediately the machine was switched on.

Kind Regards, John

 

[Risteard]

OK, found it now. So it appears it should more sensitive than the one in the CU, it's not that the CU is detecting something a type A would not.

No. So you will still have the problem.

However it does show that the use of Type AC RCDs is often inappropriate. I believe the use of Type A RCDs is very common on the continent, but not here or in Britain. (There are also Type B RCDs.)

 

[DetlefSchmitz]

It could still be a fault with the new CU wiring (neutral in wrong bar).

Possibly - but very unlikely if, as we've been told, the WM runs for ~5 mins before the RCD trips. If the neutral were in the wrong bar at the CU, one would expect the RCD to trip immediately the machine was switched on.

Kind Regards, John

That might be when the heater turns on. Depends how it works. I guess I wouldn't turn on a heater until I knew there was some water there.

 

[JohnW2]

That's not correct. An RCD is an earth-leakage circuit breaker. The use of VOELCB (voltage operated) has been discontinued but COELCB (current operated) are now called RCDs.

That's essentially true in the way that the words/abbreviations seem to be used, but (since we appear to be being pedantic) it is not really correct to call an RCD an "earth-leakage circuit breaker". An RCD will respond to any 'residual current' (L-N imbalance), even if it has nothing to do with 'earth leakage' (e.g. if there is a cross-connection between Ls of circuits on different RCDs).

On the other hand, a VOELCB really did detect (the rise in CPC voltage due to) 'earth leakage'.

Kind Regards, John

 

[JohnW2]

That might be when the heater turns on. Depends how it works. I guess I wouldn't turn on a heater until I knew there was some water there.

That's already been noted. However, if the neutral were connected to the wrong bar, one would expect the RCD to operate immediately the solenoid was activated to let water in (if not even prior to that, due to current taken by the electronics etc.).

Kind Regards, John

 

[EFLImpudence]

...and, of course, other items on the circuit - it's unlikely to be a separate circuit for the WM.

 

[jj4091]

Heater failure is a common problem on washing machines, causing the rcd to trip, especially after it goes through the fill cycle then starts to heat the water.

 

[david3456]

A few clues on the RCD helped the diagnosis. Thanks.
It's gone through a cold wash and some spin cycles. A new heater now on order.

 

[JohnW2]

...and, of course, other items on the circuit - it's unlikely to be a separate circuit for the WM.

Indeed.

Kind Regards, John