Tricksy electrical problem... please help!
Discussion
Having an electrical nightmare… any tips / advice very welcome!
A bit of background: We had our kitchen replaced a month or so ago and have had electrical problems ever since… specifically, the RCD keeps tripping, which then cuts power to everything else. Not nice first thing in the morning… the RCD trips most often when the shower is used, but it’s also happened when the heating comes on.
We turned off everything electrical in the new kitchen – lights, sockets, hobs, extractors, fridge and ovens (to keep the wife happy we replaced a single double oven with a main oven / steamer / microwave thing, a relatively standard top oven, and a warming drawer - each on their own isolation switch). We then added each element back in progressively.
Long story short, shower works without tripping the RCD until the ovens are added into the mix. When the ovens are switched to standby (but not actually doing anything) at their isolation switches, the RCD trips pretty much immediately, or very soon after, the shower starts to run.
So we then tried each oven individually…
- Main oven on standby, top oven off, warming drawer off – no RCD trip when ensuite shower used. All good.
- Main oven on standby, top oven on standby, warming drawer off – RCD trips when ensuite shower is used
- Main oven on standby, top oven off, warming drawer on standby – RCD trips when ensuite shower is used
- Main oven on standby, top oven off, warming drawer on standby – RCD trips when other shower is used (in main bathroom)
The ovens and shower are all on the main circuit (which has the RCD).. none of the other circuits for lights, sockets etc. are effected… We also have an extension to the house, with a separate Consumer Unit – this is not impacted at all.
The sparky is fairly flummoxed.... any pointers very welcome…!
Cheers,
UV
A bit of background: We had our kitchen replaced a month or so ago and have had electrical problems ever since… specifically, the RCD keeps tripping, which then cuts power to everything else. Not nice first thing in the morning… the RCD trips most often when the shower is used, but it’s also happened when the heating comes on.
We turned off everything electrical in the new kitchen – lights, sockets, hobs, extractors, fridge and ovens (to keep the wife happy we replaced a single double oven with a main oven / steamer / microwave thing, a relatively standard top oven, and a warming drawer - each on their own isolation switch). We then added each element back in progressively.
Long story short, shower works without tripping the RCD until the ovens are added into the mix. When the ovens are switched to standby (but not actually doing anything) at their isolation switches, the RCD trips pretty much immediately, or very soon after, the shower starts to run.
So we then tried each oven individually…
- Main oven on standby, top oven off, warming drawer off – no RCD trip when ensuite shower used. All good.
- Main oven on standby, top oven on standby, warming drawer off – RCD trips when ensuite shower is used
- Main oven on standby, top oven off, warming drawer on standby – RCD trips when ensuite shower is used
- Main oven on standby, top oven off, warming drawer on standby – RCD trips when other shower is used (in main bathroom)
The ovens and shower are all on the main circuit (which has the RCD).. none of the other circuits for lights, sockets etc. are effected… We also have an extension to the house, with a separate Consumer Unit – this is not impacted at all.
The sparky is fairly flummoxed.... any pointers very welcome…!
Cheers,
UV
You can have earth faults that wont trip the rcd, ie present enough earth leakage untill something unrelated is consuming current on the circuit.
Is the spark any good? A lot of reasonablish cable installers offering electrical installation really arent up to fault finding, have the analytical mind for it.
Is the spark any good? A lot of reasonablish cable installers offering electrical installation really arent up to fault finding, have the analytical mind for it.
hairyben said:
You can have earth faults that wont trip the rcd, ie present enough earth leakage untill something unrelated is consuming current on the circuit.
Is the spark any good? A lot of reasonablish cable installers offering electrical installation really arent up to fault finding, have the analytical mind for it.
Thanks - spark seems helpful, but I'm not confident he has a solution yet apart from "replace the ovens"...Is the spark any good? A lot of reasonablish cable installers offering electrical installation really arent up to fault finding, have the analytical mind for it.
Blaster72 said:
Have you tried a brand new RCD? Yours could have been just on the edge before and the new appliances have tipped it over into tripping falsely.
Hi.. I'm looking at this as the last resort as, from what I understand, the RCD is usually the least likely cause and the testing suggests its related to the ovens and other devices on this circuit...eldar said:
Shower and Cooker earthing or polarity - has any wiring been done on it? And anything else on that circuit that has been touched.
Hi, that was my thinking also.. most of the kitchen and dining rooms was touched - new lighting in ceiling*, LED strip lights under peninsula*, new fridge*, new hob, new extractor, replacement dishwasher and the pesky new ovens.Any ideas what the solution might be?
cheers,
UV
- these all required extensive additional wiring that was not there previously
Has the electrician used a calibrated RCD tester to see if the rcd is tripping at 30ma , the tester will also apply 15ma at which the RCD should not trip , this will prove the RCD before spending money on replacement .
The next test is to carry out a insulation resistance test on the appliances listed to see if there is an earth leakage .Also an IR test on the whole installation
I have to say basic stuff for an experienced sparks .
And before any one asks , over 50 years
The next test is to carry out a insulation resistance test on the appliances listed to see if there is an earth leakage .Also an IR test on the whole installation
I have to say basic stuff for an experienced sparks .
And before any one asks , over 50 years
Edited by MX51ROD on Sunday 25th September 15:05
Ultraviolet said:
Thanks - spark seems helpful, but I'm not confident he has a solution yet apart from "replace the ovens"...
Multiple faulty items is extremely unlikely although of course not impossible.If suspect they can be tested with a low reading current meter or failing this, independantly of the other circuitry before replacement...
As mentioned, first thing is to ensure all the proper tests have been done. Without that you are fishing in the dark.
I'd also be doing earth leakage tests and line/neutral imbalance test on all circuits.
Assume they really don't show a problem, I would try to get some of the suspect circuits onto there own RCDs/RCBOs. At the very least that helps narrow down where the problem is and reduces the impact while investigating it.
It might just be that you have too much general leakage on one RCD. Most modern electronic kit has noise filters from line/neutral to earth, individually the leakage caused doesn't cause a problem but put them all together on one 30mA rcd and you are asking for problems.
It might also be one particular item (key suspects are fridges/freezers/washing machines/ovens etc) with a problem. Trouble is, with a lot of those things with motors it only shows a problem when it turns on (eg fridge kicks in in the middle of the night).
It might also be something silly like a water leak into a socket etc or some idiot plastered a choc block in the wall when redoing your nice kitchen. That sort of thing should show up on an IR test though.
Lastly, don't assume it is related to the kitchen. That could be a co-incidence. It might be an outside light, socket or pond pump that has got a bit of moisture in.
I'd also be doing earth leakage tests and line/neutral imbalance test on all circuits.
Assume they really don't show a problem, I would try to get some of the suspect circuits onto there own RCDs/RCBOs. At the very least that helps narrow down where the problem is and reduces the impact while investigating it.
It might just be that you have too much general leakage on one RCD. Most modern electronic kit has noise filters from line/neutral to earth, individually the leakage caused doesn't cause a problem but put them all together on one 30mA rcd and you are asking for problems.
It might also be one particular item (key suspects are fridges/freezers/washing machines/ovens etc) with a problem. Trouble is, with a lot of those things with motors it only shows a problem when it turns on (eg fridge kicks in in the middle of the night).
It might also be something silly like a water leak into a socket etc or some idiot plastered a choc block in the wall when redoing your nice kitchen. That sort of thing should show up on an IR test though.
Lastly, don't assume it is related to the kitchen. That could be a co-incidence. It might be an outside light, socket or pond pump that has got a bit of moisture in.
Totally agree, don't ask a sparky to insulation resistance test the oven as he will put 500 volts up its chuff and cause more problems. Make sure the fixed wiring has been properly tested by a proper sparky (not a kitchen fitter who has done a 17th edition part p update). Worst case scenario have the oven put on a separate rcbo, this won't stop it tripping but won't affect the rest of the house. If you have a split load board put the rcbo on the isolator side to avoid discrimination between the rcbo and the main rcd
All
Thanks for the tips and pointers so far... will look into what testing has been done, and look to put in place individual RCBOs if only to mitigate the impact when the issue occurs. Cable guy is coming back round this week, then the spark, so hopefully will be able to get to the bottom of it..
cheers,
UV
Thanks for the tips and pointers so far... will look into what testing has been done, and look to put in place individual RCBOs if only to mitigate the impact when the issue occurs. Cable guy is coming back round this week, then the spark, so hopefully will be able to get to the bottom of it..
cheers,
UV
Sounds like the oven to me, especially if everything else works ok until its energised.
However, just switching off sockets is no good. You need to physically unplug everything as most sockets are not double pole.
Does everything else work ok when the oven isolator is off, as that is double pole?
Plus, i doubt the electrician would be interested in testing the appliances as their engineers will be the ones for that.
He needs to carry out the required testing on each new or modified circuit for his certificate and so if there was a cable problem it would have been spotted during one of the testing procedures.
If he is insisting circuit testing is ok, call the supplier or better still, the manufacturer direct.
Lastly, if the oven has been stored in a cold or damp environment for a while, this could also cause issues with the internals.
However, just switching off sockets is no good. You need to physically unplug everything as most sockets are not double pole.
Does everything else work ok when the oven isolator is off, as that is double pole?
Plus, i doubt the electrician would be interested in testing the appliances as their engineers will be the ones for that.
He needs to carry out the required testing on each new or modified circuit for his certificate and so if there was a cable problem it would have been spotted during one of the testing procedures.
If he is insisting circuit testing is ok, call the supplier or better still, the manufacturer direct.
Lastly, if the oven has been stored in a cold or damp environment for a while, this could also cause issues with the internals.
Edited by Alucidnation on Monday 26th September 20:07
I had a problem like this a while back.
Easy test to do apart from the usual EFLI, Ins res, etc.
Switch each circuit off at the MCB, remove the corresponding earth and then re energise the circuit. Test the voltage between the floating earth and the earth bar. Normal voltages to expect will be between 20-50V anything exceeding 50V will be suspect.
I had a Hob circuit test at 128V after the customer kept reporting random tripping. Called Ikea out as Hob under warranty and they have put some kind of box on the Hob and customer has not reported anything since. Im not sure what was in the box as haven't been back to the job yet.
I have used this method of fault finding for many years with great success.
Easy test to do apart from the usual EFLI, Ins res, etc.
Switch each circuit off at the MCB, remove the corresponding earth and then re energise the circuit. Test the voltage between the floating earth and the earth bar. Normal voltages to expect will be between 20-50V anything exceeding 50V will be suspect.
I had a Hob circuit test at 128V after the customer kept reporting random tripping. Called Ikea out as Hob under warranty and they have put some kind of box on the Hob and customer has not reported anything since. Im not sure what was in the box as haven't been back to the job yet.
I have used this method of fault finding for many years with great success.
pgh said:
Second the recommendation to move to RCBOs, this gives you 30mA of leakage per circuit. Given that appliances are 'allowed' to leak a tiny amount of current to earth even when new, its very easy indeed to get in a position where you have sufficient leakage to trip a whole-house (or multi-circuit in a split consumer unit) RCD. Commiserations though, these nuisance trips are hard to find and troubleshoot.
Thirded.OP, I would do this as a matter of course with the way you describe things. (In fact I did just that a few years ago
). It may not in itself fix the problem, but will be less of a ball ache when things trip and will give a stronger indication of what is actually failing. IIRC it wasn't that expensive to do.Ref your oven and shower....how far are they/how long are the cable runs from the consumer unit?
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