RCD vs Dishwasher Pump??

[NickSee]

Hi all

We inherited an Indesit DIF 16 dishwasher when we moved into our house a year ago. The previous owner told us it had started tripping the mains RCD and he’d got someone out to repair it and gave us the contact details. Sure enough a few weeks later it started tripping the RCD again, so we called out the same repair engineer, who couldn’t remember if previously he’d replaced the heater or pump. It failed to trip with him watching so he went away again.
It tripped a few more times in the coming weeks and I realised that each time it did, it tended to be near the end of a cycle with an inch or two of hot water present, so began to think it was an interaction between the heavy inductance of the pump and maybe an over sensitive RCD (modern Consumer Unit 30mS RCD).
I was working on the theory that the RCD was overly sensitive as the dishwasher continued to work perfectly over a number of months hence making me think the pump is potentially not faulty. I bought a replacement RCD, but then realised it was probably not a job I could undertake safely myself so still have not fitted it.
The DIF 16 then worked fine with no trips for about 6 months so the issue fell off my home repairs radar until now.. when we’ve suffered a spate of trips again which are really annoying (apart from everything else the trips mean my water softerner does a resin rinse which eats up salt like nobody’s business).
So I’m thinking about procurring a pump and fitting it myself – just wondered if anyone can offer any guidance. The alternative is buy a new machine and maybe sell this one off for parts….

thanks in advance

Nick

PS The engineer implied that there was a single pump which both provided the washing pressure and drained the soiled water.. but in my hunt for parts I seem to have found a sep drain pump.. it doesn’t look like much of an inductive load but given the timing of the trips is this (at £28 rather than £90 for main pump) a likely culprit?

[Martin]

Re: RCD vs Dishwasher Pump??

Heater is the most likely suspect. 😉

[NickSee]

Re: RCD vs Dishwasher Pump??

Martin thank you very much indeed for replying, please can you just give me a sentance to back up your no doubt accurate answer? Its counter intuitive to me as a non-whitegoods engineer given the water is heated without problems and the trip occurs within 10 minutes of end of program. Are you perhaps going on a corrosion / carbonating angle? If so I would offer the additional detail that I think the dishwasher is less than 4 years old, most likely 2-3 yrs old and we have a water softener.

Please don’t think I’m challenging you, I’m very grateful for the input I just want to understand before I commit to a course of action.

Cheers

Nick

[Martin]

Re: RCD vs Dishwasher Pump??

NickSee wrote:Martin thank you very much indeed for replying, please can you just give me a sentance to back up your no doubt accurate answer?

To establish the component that is causing the RCD to trip will require the use of an insulation meter. At the point in time the fault occurs to the isolate the machine and test each component in turn. I am suggesting to you that the heating element is by far and away the most likely cause though the circulating pump or any water leak a likewise caution. Without intervention and subsequent testing we can only hazard an educated guess at this point in time. 🙂

[NickSee]

Re: RCD vs Dishwasher Pump??

cheers Martin – fully appreciate the difficulty of remote diagnoses and am just very grateful that you take the time to try to help.

All I have is a trusty multimeter.. V, I or R. I’m happy to pull the machine out and try to take any meter readings that might help like coil windings etc but am beginning to sense that I have a snag that I could spend £180 on parts with a few hours of sweat thrown in and still find that I haven’t cured it (eg if it is a deeper gremlin or it is the RCD).
Maybe I should take the plunge and spend another £100 for a new machine..

[NickSee]

Re: RCD vs Dishwasher Pump??

hmmmm. Just had a trip at 23 mins 44 seconds on quick wash, I wonder if Indesit can tell me what the programmer was calling for at that point – if it was calling for heat then I’ll pay the £45 for a new heater…..

[Martin]

Re: RCD vs Dishwasher Pump??

What did your multimeter say when you tested the heater anyway?

[PGS]

Re: RCD vs Dishwasher Pump??

Firtly Martin is 100{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} correct in diagnosis, secondly your RCD is not at fault its doing the job it was designed to do. Get refund on RCD and pay a reputable repair company to accuratly diagnose the fault. Probably cheaper in the long run.

[NickSee]

Re: RCD vs Dishwasher Pump??

Just wanted to close the thread down and pass my sincere thanks to Martin (and PGS) I changed the heater and no more trips. Coil resistance on the defective unit was 34.6 ohms, with no detectable leakage to earth when cold (not surprising) I didn’t measure it when hot.
Thanks again for putting me on the right track it is really appreciated.

cheers

Nick

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