RCD Tripping - Electrician can't help!!
- Thread starter vincentbrown
- Start date
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Some of the spacings were a bit wobbly, this is how it is published in BS7671:
[code:1]
The following fixed current using equipment may be installed in zone 1 if it is suitable for that zone:
(i) a water heater
(ii) a shower pump
(iii) other fixed current using equipment which can reasonably only be located in zone 1 provided that:
(a) it is suitable for the conditions of that zone, and
(b) the supply circuit is additionally protected by an rcd with rated residual current not exceeding 30ma in accordance with regulation 412-06.
(iv) SELV current-using equipment.
[/code:1]
[code:1]
The following fixed current using equipment may be installed in zone 1 if it is suitable for that zone:
(i) a water heater
(ii) a shower pump
(iii) other fixed current using equipment which can reasonably only be located in zone 1 provided that:
(a) it is suitable for the conditions of that zone, and
(b) the supply circuit is additionally protected by an rcd with rated residual current not exceeding 30ma in accordance with regulation 412-06.
(iv) SELV current-using equipment.
[/code:1]
Yeah, it is almost the unwritten regulation i.e. most sparks wouldn't fit a shower without RCD protection. The 17th edition of BS7671 looks as though RCDs will be mandatory in this instance. At present it is not a requirement of the current version of BS7671. If the manufacturer says an RCD is required then one must be fitted.
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I suspect that there is no fault to find.
Remember any circuit will exhibit a low current to earth leakage through the cable resistance and capacitive and inductive reactances. I usually assume a natural leakage of around 5mA per circuit. Depending on the installation, each circuit can be higher than this. In your case you have around 8 Circuits on one RCD (I think), you are therefore going to run fairly close to the 30mA earth leakage under no load conditions. I suspect if you isolate ANY two of your circuits then your spurious trip will not happen. The circuits isolated will not be faulty but isolation will remove a few mA's of earth leakage current and as such take the RCD away from the trip point. The spurious trip will be caused I suspect by all sorts of undefined condition not least of which could be humidity or temperature.
If you want to keep all your circuits on RCD protection, try installing two with four circuits on each.
This also answers why your RCD was OK before extending your electrical installation. The new circuits have merely taken the RCD closer to the trip point by virtue of natural leakage caused by the fact the cable insulation resistance is not infinite.
Remember any circuit will exhibit a low current to earth leakage through the cable resistance and capacitive and inductive reactances. I usually assume a natural leakage of around 5mA per circuit. Depending on the installation, each circuit can be higher than this. In your case you have around 8 Circuits on one RCD (I think), you are therefore going to run fairly close to the 30mA earth leakage under no load conditions. I suspect if you isolate ANY two of your circuits then your spurious trip will not happen. The circuits isolated will not be faulty but isolation will remove a few mA's of earth leakage current and as such take the RCD away from the trip point. The spurious trip will be caused I suspect by all sorts of undefined condition not least of which could be humidity or temperature.
If you want to keep all your circuits on RCD protection, try installing two with four circuits on each.
This also answers why your RCD was OK before extending your electrical installation. The new circuits have merely taken the RCD closer to the trip point by virtue of natural leakage caused by the fact the cable insulation resistance is not infinite.
However, when we returned from our Summer holiday in the August, the RCD had tripped again and we returned to find my daughters tropical fish had died and two warm freezers full of food!!
Just a thought, which may not help now, but could in the future. You could install a burglar alarm that would be able to send a telephone message when there is a power cut or your supply fails. Then you should not have to lose your fish or food in the freezer. Somebody would be immediately notified and can therefore take the appropriate action!
Just a thought, which may not help now, but could in the future. You could install a burglar alarm that would be able to send a telephone message when there is a power cut or your supply fails. Then you should not have to lose your fish or food in the freezer. Somebody would be immediately notified and can therefore take the appropriate action!
S
sparkyspike
Or just make sure important appliances aren't on an RCD.
The point about things only happening from the CHANGE ( in circuits and RCD) are a good starting point.
BUT are not conclusive so do not be ready to jump to that as a near certainty.
Your electrician should have tested the RCD and all the circuits.
Your equipment and/or a fixed wiring fault might all be contributing small leakage currents that once added occaisionally exceed the trip threshold.
Main culprits are usually water carriers such as steam iron, kettle then washers/dishwashers then cookers/showers then computers but an old damp socket/switch (in the back box) can cause havoc.
Intermittent faults can be a right pain to solve sometimes.
Try to look for a common denominator for clues.
I`m a little dow on your electricians response as you give it though
BUT are not conclusive so do not be ready to jump to that as a near certainty.
Your electrician should have tested the RCD and all the circuits.
Your equipment and/or a fixed wiring fault might all be contributing small leakage currents that once added occaisionally exceed the trip threshold.
Main culprits are usually water carriers such as steam iron, kettle then washers/dishwashers then cookers/showers then computers but an old damp socket/switch (in the back box) can cause havoc.
Intermittent faults can be a right pain to solve sometimes.
Try to look for a common denominator for clues.
I`m a little dow on your electricians response as you give it though
the fact that this guy had 11 years with out the rcd tripping and then on cu change has all these probs tells me something
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AHHHHHHHHH!!! Just triped again at 21:17 (Sunday 7th May)
My thoughts are to have to go for spliting the RCD circuit up into smaller, separate RCD circuits. Having removed the conservatory ring and outside shed power, I am back to what I had pre the new CU.
I think that I am right in saying that to do that though, I would have to have the CU changed again as the current one only has two sides, one for RCD and one for Non RCD, I am correct in thinking this?
I think I will isolate the immersion heater tomorrow to also remove that from the equation as some of your responces indicate that these are sometimes the culprit.
Sparky, how do I put important appliances on the non RCD side of the CU. Surely I would have to put the ring mains that those appliances are on, on the non RCD side. We have a freezer in the utility which is part of the kitchen ring, and another in the garage which is on a separate ring. Making these non-RCD isn't allowed is it?
As a separate point which may or may not indicate anything, sometimes when I reset the RCD, the switch has to be toggled a few times before it will stay on, is this normal or is it due to the fault that I have?
Hysteresis, I understand your thoughts on number of circuits etc but I do not believe that we are unusual in the number of circuits / appliances that we have, and having removed last years additional circuits we are back to what we had before which caused no problems for over 10 years - although I couldn't be sure that all of the cicuits on the RCD side now, were on the RCD side of the previous CU!
Better go before the ******* thing trips again - I am surprised that this computer is still working after the number of times it has been powered off by a power cut!!
My thoughts are to have to go for spliting the RCD circuit up into smaller, separate RCD circuits. Having removed the conservatory ring and outside shed power, I am back to what I had pre the new CU.
I think that I am right in saying that to do that though, I would have to have the CU changed again as the current one only has two sides, one for RCD and one for Non RCD, I am correct in thinking this?
I think I will isolate the immersion heater tomorrow to also remove that from the equation as some of your responces indicate that these are sometimes the culprit.
Sparky, how do I put important appliances on the non RCD side of the CU. Surely I would have to put the ring mains that those appliances are on, on the non RCD side. We have a freezer in the utility which is part of the kitchen ring, and another in the garage which is on a separate ring. Making these non-RCD isn't allowed is it?
As a separate point which may or may not indicate anything, sometimes when I reset the RCD, the switch has to be toggled a few times before it will stay on, is this normal or is it due to the fault that I have?
Hysteresis, I understand your thoughts on number of circuits etc but I do not believe that we are unusual in the number of circuits / appliances that we have, and having removed last years additional circuits we are back to what we had before which caused no problems for over 10 years - although I couldn't be sure that all of the cicuits on the RCD side now, were on the RCD side of the previous CU!
Better go before the ******* thing trips again - I am surprised that this computer is still working after the number of times it has been powered off by a power cut!!
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Sufolklad, Please Please Please, What does it tell you!!!
All it tells me is that the old RCD may not have been working, or it may and a new fault has been caused.
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