RCD Tripping query

Discussion in 'Electricians' Talk' started by Daniel hogg, Dec 8, 2020.

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  1. Daniel hogg

    Daniel hogg New Member

    Hi all,
    The rcd in my single rcd consumer unit keeps on tripping.
    It first happened when I turned the kettle on. It then happened when I turned my shower on. Both of these times my portable radiator has been on. I have tried the kettle and shower both at the same time and individually when the radiator was off and they were fine. With both of those devices off and the radiator on, the RCD trips again after about 20 min. I therefore think it is the radiator causing it to trip. If I buy a portable RCD and plug it in and then the radiator into it, if it trips the portable RCD, would this confirm that it is the radiator at fault?

    All sockets in my flat appear to run off this one RCD. I have tried the radiator in multiple sockets and it still happens. Everything was fine until recently. I just don't want to spend on getting an electrician in if its just the radiator being dodgy.

    Any advice appreciated.

    Dan
     
  2. MGW

    MGW Screwfix Select

    Oh dear, your not going to like this, it seems you have an earth - neutral fault, when there is no load earth and neutral are the same voltage, but as the load increases the voltage between earth and neutral also increases, so the current follows ohms law, V/A = Ω so as the load increases the leakage to earth also increases.

    So to find the problem we need to check the resistance between neutral and earth of equipment being used, and it seems likely from what you have said the radiator has a problem.
     
  3. Bob Rathbone

    Bob Rathbone Screwfix Select

    MGW has a point, but it may also be caused by cumulative leakage, that is, each appliance has some earth leakage, individually not enough to trip the RCD. Combined their is enough leakage to cause tipping. It may also be an over sensitive RCD.
     
  4. If everything works fine when the portable radiator isn't plugged in (not switched off but unplugged) then I rather think you have answered your own question. Buying a new radiator would be cheaper than an electrician's call out.
     
  5. Daniel hogg

    Daniel hogg New Member

    Thanks for your advice guys! Pretty much confirmed what I though. I will try and find a similar radiator to test, but I think it is the current rad causing the problem. Its strange that the first time it happened all 3 were on, but now it just happens when only the rad is on and the other 2 are off. Would it be worth me checking all the plug sockets to make sure there is no loose wiring?
     
  6. spirits are real 2016

    spirits are real 2016 Screwfix Select

    Yes it would be worth checking the wiring of the socket where you plug in your heater and have you put any pictures or anything else up on the wall near the socket.. turn power off first for your safety..
     
  7. Daniel hogg

    Daniel hogg New Member

    Thanks :) It happens whatever socket I plug it into (which makes me think the Rad is at fault even more). Could a loose wire somewhere completely different, but on the same circuit, to anything i'm plugging in, still cause an issue?

    No, nothing changed near any of the sockets.
     
  8. spirits are real 2016

    spirits are real 2016 Screwfix Select

    Have you checked inside the heaters plug for a loose connection or changed the plug altogether for a new one that could also be faulty..
     
  9. Daniel hogg

    Daniel hogg New Member

    Yeah, took the front cover off the heater and checked. There was no lose wires, one wire looked like it had a nic in it though so wrapped in some electrical tape. Didn't change the plug, but did change the fuse as I had some new 13A fuses going spare. Made sure every connection was tight too.
     
  10. Rick1632

    Rick1632 Active Member

    So without the heater plugged in, and EVERYTHING on - shower, kettle, washing machine etc it's fine, but if the radiator is plugged in and turned on, then when you turn on any high powered device the RCD trips??

    Clearly the radiator is faulty.
     
    Daniel hogg likes this.
  11. spirits are real 2016

    spirits are real 2016 Screwfix Select

    It sounds like the heating element is fawlty have you got cold only option on your heater if so run that and see if it trips if it dosent the element is fawlty if it trips the fan is fawlty..
     
  12. MGW

    MGW Screwfix Select

    In the main, items like heaters only switch the line, neutral is always connected, so an earth to neutral fault will still exist does not matter if switched on or off, only unplugging will remove it.

    Neutral is with no load the same voltage as earth, so even if connected together it would not likely trip a RCD with a TN system, but as the load increases the voltage at the neutral raises due to the resistance in the neutral cables. So the more load, the greater the potential difference and the more current that will flow, simple ohms law, I = V/R so higher the V the higher I is. And the more the load is the higher V is in respect to earth in the neutral.

    Many elements are made using mineral insulation, this is hydrophobic i.e. it attracts water, so the ends of the element needs sealing, if this seal fails it absorbs moisture from the air, and although one can heat the element up and drive out the water, it will just absorb it again, so in real terms needs new element. Mainly a problem found with ovens.

    Since you have worked out what has failed it seems pointless to call an electrician, likely get a new one for just over £30 so not worth repairing.
     

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