I seem to be getting a lot of RCD failures when the RCD does not trip with the test button of with the RCD tester.
But after manually turning the RCD off and back on it works within spec.
So give yours a test. It could save you from a belt.
I am not a fan of extra regulation without cost-benefit assessment but that seems a strong case to at least explore with stakeholders requiring landlords to give tenants advice/instruction to test RCD(s) every 3 months. Could be added on to the requirement to give them a copy of the EICR.
I'm surprised an RCD that's temperamental like that isn't regarded as faulty and needs replacing? Who's to say how quickly after TIOATIOA it becomes temperamental again?
One of mine trips several times a week, whenever their is a brief power outage, which is that often, although perhaps there is a lot of baseline earth leakage.[1} Is this common, it is a little annoying?
[1] I can't reset it without disconnecting one of the power circuits quite often, one day I'll look into it.
Adam is suggesting that all householders should do this, so why should tenants need special advice?
Mind you, I haven't had a gas safety check done in the 22 years I've lived in this house.
I have had different views on that.
Possibly because they do not do any electrical DIY!
But seriously I am suggesting that any readers of this post actually try their RCD test button if they have not done so for years.
Would connecting up a low wattage bulb between RCD live and non-RCD neutral so that a known number of millamps creates an imbalance - and should trip it ??
Our (whole house) RCD frequently tripped. It was pretty well on the edge all the time due to the number of items of computer equipment with their leaky filters (a dual PSU server, 4 and at times 5 PCs, plus printers, satellite boxes, etc.)
I have had no problems at all since I took out the RCD and fitted RCBOs
- a slightly complicated task as it is an old Crabtree Starbreaker with a 14-way busbar that needed to be changed from a split one to a continuous one ... and you can only buy the 15-way versions for the newer Starbreakers. In the end, I had to buy a 15-way, carefully remove the end plastic (which includes the mounting), cut down the busbar and re-attach the end.
Surely that's basically what the RCD's own test button does and just connects a known resistance between its outgoing live and its incoming neutral?
I am not suggesting tenants /need/ special advice.
I am suggesting the way landlords must give tenants bumf about their installation at least once every 5 years may provide a cost-effective way to remind to test their RCD(s) periodically. (But I would also wager tenants are on average more clueless about such things.)
I am agnostic as to whether it would be cost-effective to remind other householders.
How about we start with a survey of a totally unrepresentative sample of what happens now. When did you and others last test your RCD(s)?
[I check mine once a year with a (many years-since-it-was-calibrated) tester - starting at the lowest current and working up. But then I'm cautious 'cos I know the numpty who did most of the wiring.]
I test mine (a local one on the extension lead) before cutting the hedge.
Might be worth looking for the earth leakage. Immersion heaters are big suspects in that sort of borderline trip thing. Mine went to a hard fail a few weeks back but there were hints of something every now and then.
You might want to look at the offending circuit to find the fault.
I had an interesting one that was a hard fault in the kitchen ring main that really wouldn't go away. Turned out the kitchen fitters had put a 2 connection junction box on the floor with the lid on allowing 3 ways in and a slug had got into it and then been electrocuted.
Dead slug and slime proved to be remarkably conductive :(
No idea how the slug came to be in the kitchen.
With a meter, never.
With the test button, I'll go and do them both now.
It would have been slightly handier to do them before I reset the mains clocks yesterday.
Owain
Which reminded me, why is it that a breaker of any type often seems, maybe through never having been tripped for years can take too long to trip when it finally does have a fault to protect against which can often mean a whole fitting needs to be replaced due to overheating. Is it just build up of crud or whatever, and should one say every few months manually trip these one at a time to make sure they keep healthy?
Brian
Ping ARW!
I promised a follow up to the EICR performed on my rental house last Friday.
4 C3 advisories.
As mentioned before, a 10mm earth wire comes out through teh wall and disappears into the gravel. Removing said gravel woould then reveal the top of the earth rod and the earth rod connection. I shall fit an eartth rod inpection box to resolve this one
The Sparky clear was not concerned that there was no RCD or MCB or RCBO in teh garage CU, its just a simple on off switch followed by 2 ceramic catridge fuses.
In his defence, he did follow back the SWA to a 13A fused neon switch in the lounge which in turn is connected to a 32A RCD & MCB protected ring main.
These 6 are:
Hob Double oven Lights up lights down Smoke alarm/emergency lights/intruder alarm Outside lights.
(There are 3 further circuits that are protected by a single RCD, which is
kitchen sockets Boiler Whole house sockets (its a 2 bed semi)
This one puzzles me a little as all there is in the bathoom is a ceiling light, a wall unit light and an extractor fan on the upstairs lighting circuit and is one of the 6 circuits mentioned in No 3.....
I happen to have some spare ways in the CU so I am actually tempted to rip out all the MCBs and the RCD and put in 9 RCBOs.
Howeever, is it an issue if the RCBOs are NOT teh same make as the CU casing
or would I be better off replacing the whole CU with a fire retardant case and with matching make RCBO's?
It is normally printed on the front of them that they should be tested periodically. But you are not alone in not seeing that!
I think Brian might be referring to how MCBs (and RCBOs) perform with over current rather than how RCDs (and RCBOs) perform with an imbalance. Testing how breakers perform with stable, over & short-circuit currents requires special kit. I'd be interested to know if even Adam carries it routinely.
I presume this is because 18th edition says all circuits should have RCDs. Therefore it's not to current regs, but was to regs at the time it was installed. (Likewise plastic CUs)
Similarly, but also a higher risk in bathrooms. I don't suppose any of those things might be within reach?
MCBs, RCBOs, etc are certified to operate with a CU from the same manufacturer. Doing it differently would be 'not in accordance with manufacturer's instructions' which could get you another C3.
More practically, different manufacturers (or ranges) have different types of busbars so the RCBOs may not fit the tangs on the busbar. An imperfect fit could cause overheating and fire risk (as could improperly screwing down the wires).
That would resolve the issue. But could you not install RCBOs from the same manufacturer as the CU? Replacing the CU would be notifiable work, whereas (arguably) replacing an MCB with an RCBO wouldn't (although you should perform RCD testing).
Some RCBOs are taller and may not fit, depending on how the wiring goes in there. You would also need space on the neutral bar for the neutral tails, as well as possibly a slot on the earth bar for a functional earth. It may end up needing a new CU if it won't all fit, and there is something to be said for metal CUs.
It sounds like it's currently satisfactory at present - depends how much work you want to pay for...
Theo
(IANAelectrician)
Thanks for getting back.
I am amazed that the plastic CU was not noted as C3. I would have noted it.
I knew the earth rod and cables in plaster less than 50mm would be C3.
As for the bathroom if there is supplementary bonding (usually to rads, sink bath etc back to the light fitting) then it is a C3 (not to current regs but met the regs when installed). If there is no bonding it's a C2.
Please do not put a different make of RCBO in your CU. What make is it that you cannot get RCBOs for (or you can but they are £100 each).
My advice would be that (as you are already prepared to pay for 9 RCBOs) then you might as well swap the CU for a metal one and leave enough space in it for a SPD if it becomes a reg in a few years time. Or even fit a SPD with this CU change. I believe that SPDs will be mandatory in a few years time on all CUs.
Finally - I always make a note if the smoke alarms are past their replace by date. There is no reg that says I can class that but it's always good for good landlords to know that they need replacing.
OOI what brand(s) of CU do you prefer? We're likely going to need one replaced soon, so I'm currently canvassing for opinions as to pros and cons. Space is a bit constrained and I'd like to fit as many ways as possible (including an SPD).
Theo
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