I came home after 3 weeks holiday to find no electricity. I have a split load consumer unit. The unprotected circuits were ok until I switched on one of the lights and a bulb blew and tripped that MCB. I switched on the protected circuits expecting the RCCD to trip out again but it has been ok. I guess that the power was off for about 2 weeks judging by the contents of a freezer in the garage. Is it normal for an RCCD to trip without a definite faulty device. What was likely to have tripped it out?
You might want to consider making sure certain things are not RCD protected, such as fridge/freezer, central heating (and any other frost protection), alarm, pet life support systems (use individual RCD), etc. Generally, non-portable appliances don't benefit much from RCD protection. To some extent, this also depends on your system's supply earthing type.
Impossible to say. Is there anything which no longers works?
Could be absolutely anything, particularly if you have the RCD protecting a garage, where wires might get damp. It is the reason that it is advisable to (a) split into several different RCDs or RCBOs and (b) put fridges and freezers on independent circuits with as little RCD protection as is allowed by the regs for the earthing system in use.
I wouldn't be concerned by a single unexplained trip. If they start getting more frequent, then you may have a faulty appliance or wiring.
My main bug bear with RCDs is regarding suppression. Most machinery such as washing machines usually have suppressors (capacitors) between power and earth. A result is that earth currents flow causing an imbalance between live and neutral. Some years ago I had to remove a suppressor from a dishwasher to stop the RCD from tripping.
If such suppression is fitted the RCD becomes very sensitive to mains spikes which I experienced recently due to a deteriorating sub-station. Other houses around here don't have RCDs and hence weren't affected.
I'm not sure if the regs allow connecting things like freezers to the mains without RCDs in the same way lighting circuits need not have an RCD. My understanding is that new wiring, PME excepting, all outlets should have an RCD.
Absolutely not. There is no requirement for socket outlets to have RCDs unless they are likely to supply outdoor equipment. A single socket clearly intended for the purpose of a fridge freezer will not fall under that category. Indeed, if you have a dedicated IP rated outside socket, or no garden at all, then it would be easy to claim that all sockets indoors are exempt from the requirement to have an RCD.
However, it is good practice to RCD protect all sockets that aren't intended for the sole use of fixed appliances such as refrigeration and laundry for secondary protection against direct and indirect contact.
Not quite sure if that claim is worthy of the term "understanding", I'm afraid.
There's no requirement *at all* for supplies to normal appliances inside the house to have RCD protection. RCD protection is required for sockets where it's "reasonably foreseeable" that outdoor portable appliances will be connected: and the normal interpretation is that ground-floor rings therefore should be on an RCD - though if you make other, convenience arrangements for outside power - e.g. 13A or other external sockets at several points - you can argue away from RCDs on the internal
-only ring(s). The Regs also require RCDing sockets in bedrooms with shower cubicles (i.e. a room which isn't a bathroom as such, so can have socketses, but does have a shower cubie in the corner and socketses in the same room but Far Away), and in a few other Special Situations.
With a TT supply (*not* PME, or the other common supplier-provides-an-earth arrangement) a 100mA RCD is required/recommended, as the local earth spike can't be relied upon to produce a low enough resistance to get enough current to flow to reliably trip MCBs/blow fuses in the event of a phase-to-earth fault. But the 100mA rating is too high to do anything much for personal safety protection...
Check outside lighting if you have them & on the RCD: o Very common for light fittings to get wet this time of year o Does not take much to trip an RCD
Quite a few Merlin Gerin bulk-pack RCBOs on Ebay right now, not mine & no connection with me - but 4-5 for about £55. That is the same price as one single Merlin Gerin RCBO.
Another possible cause is computers. Do you have more than one? One office I worked in had constant problems with tripping (electrical variety) until the trip was changed to 100mA. It only started when computers were used on that circuit for the first time. I have a problem at home that seems to be linked with PCs. Surprisingly it happens when a UPS box is switched on. I'm changing the consumer unit to have parts of the system non-protected.
Its not unknown - if the loading is marginal due to slight leakeg (RFI flters etc) and you get a power surge - lightning strkes here do it for us - the darned things will trip
I am deeply garteful that my washing machine troipped the RCD, because oitherise the dangerous partial short to earth might habve gine unnotoced. Of course uts eartherd, ut if one cable can go, so can another, and loss of earthing does not get detected untl you get a nasty shock off it.
Yes, definitely. With two computers, two printers a PaABX, a router, five TV;s and three stereos all on 'standby; or in action, I simply cold not keep mine from randomly tripping whenever anything was switched on. Now up to 100mA and its stable.
But even so, there is enough general leakage that a blowing bulb or a power surge can take it out sometimes.
IOf there is libve to earth capacitance, there is some leakage. RFI filters have precisely that in them.
Add a voltage spike, and you can get momentary high imbalance.
Pls how much wioring is in teh roof, where mild condesation may alow leakage? etc etc.
Earth lakage is a fact of life. Someties it all gets too much and the thing trips.
What I SHOULD have done apart from uprateying teh whle house to 100mA, is to add RCBO's to the specal circuits - the ones feeding outdoor stuff. I have, for example, a Klargester fed by an underground cable to a switch box that is permentrly in the rain...
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