Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 13 replies
  • Subscribers 32 subscribers
  • Views 1614 views
  • Users 0 members are here
Options
You may also be interested in
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Fault Finding-Comedy of Errors.

Zoomup

My customer reported that her washing machine repair man said that the protective device in the consumer unit was over sensitive as it kept tripping. I had installed it a few months back, it is a B16 R.C.B.O. It supplies just the single socket for the washing machine, nothing else.

Yes it did trip off after about 5 minutes when the machine was first turned on.

I could only detect a small earth leakage.

My customer said that she had plugged it into a kitchen socket via her extension lead to try that. It tripped off again very quickly, within 5 minutes.

A faulty washing machine I thought.

But no, it turned out to be a thermal overload trip on her extension lead that had tripped off.

I replaced the R.C.B.O. and tried the machine again in the kitchen socket that ran through a 30mA R.C.D. No tripping this time. Unfortunately the R.C.D. was faulty and would not trip off on test button or by my tester.

Then I tried the machine on the new R.C.B.O. It tripped it off in under 5 minutes. Two faulty R.C.B.O.s. NO I thought, that is just too much of a coincidence. A faulty batch?

After a while the machine ran without tripping off anything. I assume that damp got into the heating element and my forcing it to run dried it out. The problem is that when I took the top cover off the machine I could not access the heating element terminals, just E.L.V. circuit board stuff (5V-12V). The main ON/OFF switch is just an E.L.V. circuit board control not a mains switch.

Results. Faulty R.C.D. found and replaced.

Waste water hose leak repaired. But no water inside the machine.

R.C.B.O.s confirmed as being within spec.

Washing machine repair man will be advised of my suspicions about the electrically leaky heating element.

When fault finding check, check and check again to confirm the truth of the matter.

Although others' observations and comments may be useful, take them with a pinch of salt.

 

 

Z.

 

 

 

 

 

Parents
  • 0

    Concentric ceramic or mineral insulated heating elements can “pinhole” in their outer metal covering, or seals break behind the machine, and moisture can get in, causing RCDs to trip. When this happens too frequently, the element should be replaced. To check it's the element, an insulation resistance test can be carried out (coupled current-carrying pair to PE), but it's no good doing that when the element has been working as water might be boiled out of the element.

    BUT

    It's not the only electrical/electronic component submerged in water, that's susceptible to corrosion, and might cause an RCD to trip. Thermocouples or thermal overload cutouts that are used to monitor temperature in the drum can also suffer from “pinholing” of the stainless-steel part that goes into the grommet and faces the water itself inside the drum. Even if this isn't directly connected to PE, it is through contact with the water (containing salts to make it somewhat conductive), and the PE of the heating element.

    It's rarely the pump, as the wiring and electrical components of the pump get nowhere near the water … especially with the modern bearing-less pumps.

    Occasionally something like a door interlock (or damage to its associated wiring) might be the cause of an RCD trip as well.

Reply
  • 0

    Concentric ceramic or mineral insulated heating elements can “pinhole” in their outer metal covering, or seals break behind the machine, and moisture can get in, causing RCDs to trip. When this happens too frequently, the element should be replaced. To check it's the element, an insulation resistance test can be carried out (coupled current-carrying pair to PE), but it's no good doing that when the element has been working as water might be boiled out of the element.

    BUT

    It's not the only electrical/electronic component submerged in water, that's susceptible to corrosion, and might cause an RCD to trip. Thermocouples or thermal overload cutouts that are used to monitor temperature in the drum can also suffer from “pinholing” of the stainless-steel part that goes into the grommet and faces the water itself inside the drum. Even if this isn't directly connected to PE, it is through contact with the water (containing salts to make it somewhat conductive), and the PE of the heating element.

    It's rarely the pump, as the wiring and electrical components of the pump get nowhere near the water … especially with the modern bearing-less pumps.

    Occasionally something like a door interlock (or damage to its associated wiring) might be the cause of an RCD trip as well.

Children
No Data

Community Rules & Guidelines