Re: RCD keeps tripping

Thanks for that information Judd. The RCD I used to have was of the type where a reset button is pressed should it cut off. I tested it that way before each use by pressing the 'Test' button and then the 'Reset' button. That RCD went faulty hence what I was told about the consumer unit RCD cutting off quicker. So what you are saying indicates to me that using a separate RCD in the socket is a double-safe precaution?

Not much chance of me picking up any live cables or wires, I am always having family taking the mick out of me as I will not even unplug a device from the wall socket without turning off at the socket first. The same with my computer and when recharging my mobile phone. One of those people, the son-in-law, will change devices like the heating wall thermostat or a timer on an immersion heater without even turning off the supply at the mains – rather him than me!

My father was a qualified electrician by trade. I once saw what happened to his hand when some idiot used a six-inch nail instead of the correctly rated fuse in the domestic mains supply box. That blew a hole in his hand in the flesh between thumb and index finger. Not a nice way to learn something but a very good lesson in not what to do!

Re: RCD keeps tripping

Do you know what kind of tester he used? Earth-Loop testers are designed create a fault current which measures the value of the earth within your house. With the older type of tester, that fault current is too high to be used when an RCD is present and so will trip them off. Modern day Loop-Testers are designed for use with RCDs as the fault current they generate isn't enough to trip them.. It could be that his tester is the cause of the problem in that instance. I would suggest that if everything else is plugged in and not causing any issues, it can only be his tester.

If he comes back, see if he has a proper RCD tester as well as a loop tester. An RCD tester is set to the value of the RCD (30mA) and when operated should trip the RCD within a certain time (200ms in the case of your consumer unit). The testers also have a `Ramp` test feature to check for nuisance tripping. When used, the tester slowly increases the fault current in stages until the RCD trips - if it trips well below the 30mA set on the RCD it could be that the RCD is too sensitive.

As for the intermittent tripping, have you got anything on a timer or perhaps an outside security light? If the light turns on at night that could cause the trip. Electric irons are known to sometimes switch RCDs off occasionally because when the t/stat operates, it generates a spark which can leak to earth.

When you aren't using any appliances, leave them all unplugged for the time being. TVs and such aren't affected so they can be left on. Leave the suspected PC off too. If the RCD stays on during the night, you can begin to plug in the appliances one at a time. A bit of a faff I know, but without the proper test equipment to trace any faults, it's the only way. If the RCD trips off at night when everything is unplugged, look into the outside light hypothesis if there's one fitted.

Re: RCD keeps tripping

I applaud you for that - always a wise precaution. Re: your dad's hand, I've seen that on many occasions - a sparky mate of mine nearly lost his left hand for much the same reason - some idiot hadn't fitted a brass armoured cable connector gland properly so when he was forced to move the cable slightly, it shorted to earth and he was caught in the blast.

Re: RCD keeps tripping

Thanks Judd, I will see if the boiler quote man can tell me what sort of tester he was using.
We do have an outside light that will come on if something comes onto our property at night, might be that. Will try some of your suggestions.
Do you know if parts for that installation are available?

Re: RCD keeps tripping

Yes, electricity is dodgy and powerful stuff, I have the greatest of respect for it. This particular incident was after the event when my father was on call for anything to do with the mains fuse. Things like property fires when the supply had to be made safe etc. What he had done with this one was to take the six-inch nail out, clean all round where the fuse fitted in and then put in a new fuse. He then closed the cover, all was still OK and then he pushed down the large handle to turn the supply back on, there was a flash and a large hole appeared in the cover of the unit and also in his hand. What had happened was the original fuse had blown, the six-inch nail had been used to replace it and that it seems had made rather a noisy, large flash which had deposited lots of carbon on the inside of the unit and its cover, that allowed it to track along the carbon on the cover and short out after the correct fuse had been put in and the supply reconnected.

Re: RCD keeps tripping

You may not need any new parts if everything is working as it should. Your consumer unit is fairly modern when compared to the original wired fuse type, which incidentally, there's nothing wrong with. As long as something was installed under the regulations at the time, no-one can force you to upgrade anything just because the regulations have changed. The only exception to that is if you have any new wiring installed - that has to comply with the latest version of the Regs. In some cases, the original consumer unit can remain and a new one installed for any new wiring.

Re: RCD keeps tripping

I've seen the old `nail trick` as well as cigarette foils wrapped around fuses. People don't realise how much current flows under a short circuit - sometimes in excess of 33kA. Enough to kill someone or at the very least cause them some injury as was the case with your dad.

Re: RCD keeps tripping

They also don't realise that the fuse is there as the weakest link and is designed to fail or blow as a safety device to cut the supply in the event of a fault developing.

Re: RCD keeps tripping

Worth paying attention to Judd, if you don't know what you are doing with electricity then leave well alone.

I learnt that as a young apprentice , another lad who joined the firm at the same time a me was electrocuted to death on a site we were on. Young Brian was working in a busbar riser chamber and had remove the fuse and left it on top of the switchgear. Some idiot from the firm we work working at decided he needed power on one of the floors So he put the fuse back in (not one of you domestic type but a big industrial one) ans threw the switch. No health and safety back then and the qualified electricians failed to teach about what to do or not. Something I will never forget and that was nearly 60 years ago.

even a 240volt shock knocks you back a bit having had a couple in the past while learning the trade.

What i learnt back then has completely changed ,even the wiring. I learnt on wiring before it went metric such as 7.029 or 3.036 size to name but 2.

So now ,even today I have called in a qualified electrician to check out our cooker circuit before the new oven comes. he said it looks ok but will do a proper check and give us a pass certificate

Yes what went on back then would horrify people now, but it was more or less accepted. Some of the things I have seen like a man on one site we were on saw another electrician and picked up a bit of conduit( metal pipe) and hit him over the head with it knocking him out, some friction in the past i found out.

Another was a guy falling into a lift several stories up shaft before the lift was installed and landing on the shock absorbing springs tha carriage would sit on, died of course. no barriers around the lift shaft hole

Me I have been lifted in a tower crane bucket to get conduit up to the top floor of a building and the crane driver though it was fun to have the bucket swing while I was hanging onto a couple of bundles of conduit.

Yes learning a trade was tough back then but you had to accept it . Just a couple of examples I will never ever forget and i was only 16/17 years old at the time

Re: RCD keeps tripping

Something similar happened to me - I was working in a cabin erected at a new caravan site for the use of all the power supplies and metering. It was completely dead and safe to work on, that is until some dozy tw@t of an overhead linesman decided to connect the cabin to an overhead transformer without telling anyone - the shock threw me out of the door and sent me rolling down a hill. I bet it was comical to see but you can imagine the few well chosen words aimed at that linesman. I can laugh about it now I look back on it but in reality, I could have been killed.