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[roycv]

Hi thank you for the advice.
When I was at work on one occasion I was explaining to the company electrician (Glaxo laborotories Computer centre), showing him the wiring drawings, what we would be doing to the Motor / alternator 3 phase system supplying the computer room.  The controls that were stuck in delta mode and welded solid how we suspected a particular relay as not working and causing the problem.  He looked at us for a minute and said he would be in his office if we needed any tea.

I know where every wire goes in my house and wired up all the downstairs lighting myself.  I am very conscious of fire risks and have got rid of all of my halogen lamps as I think they run dangerously hot and gone over to LED lighting.
I have worked around 3 phase and single phase mains for all of my working life.  I also know when to step away and let a professional take over.

I have designed control systems inside a small steam boiler switching mains power through solid state mains relays to heater and pumps using digital technology.  Used in a well known but old name supermarket 90 odd of them were made and not one unit ever failed.  Each unit had a serial number with a history of the build in a reference book.

I do not see that an extension lead and a RCD unit are going to be beyond my ability to resolve.

I know your intentions are of the best but I thought I better give you some background.  I do appreciate all the input which has now got even more complex.

The installers who never finished the installation saying they needed to return to fit something else are no longer employed by the energy company I am with.  EDF energy when I phoned them said they were too busy to answer the phone.
On the plus side we have energy supplies I took meter readings and I shall relax and see how they wish to use the slighly-not-quite-installed smart meters in the future.
For others I have unplugged the radiator and will see if the consumer unit still trips just on the garage supply.

Regards to all
Roy

[Taranis]

Very much electrical work comes under the heading of "competent person" These days its against the grain to work on anything live and only an idiot or an expert would do this, the latter in special circumstances. Personally I never thought for a moment that you were incompetent Roy 

[Stan]

HI Roy thank you for explaining your working life you seem more the qualified to fix the problem. I did mean any offence with my replies  I was just pointing out the dangers of working with electrics but I did not know your background.

Stan.

[Taranis]

I would like to add that there is nothing wrong with using a fit for purpose RCD protected extension lead to feed outdoors anymore than the tens of thousands of caravan motorhome and yacht hook ups world wide that don't catch fire.

[tr7v8]

Reading this I have a thought. Most installed kit, like smart meters is hardwired. It could very well have a high leakage current, in excess of 3.5mA. If this is the case then your RCD will be 30mA, so the breaker maybe running closer to the the limit of 30mA with the smart meter installed. The heater may just push it over the limit.


I've seen this in computer rooms where some idiot electrician has installed an RCD and everyone is wondering why you're getting nuisance tripping.


You need a sparks on site with a PAT tester & a RCD test meter. My gut feeling is you have something in the house that's a bit leaky, Ovens & freezers are favourite. The leak isn't enough to trip the RCD but possibly puts it close.


PS LOL at the competent person bit! I have seen some true horrors from competent people, even signed off as Part P.

[Taranis]

Many competent persons have more experience than the idiot electricians you speak of. Tar & Brush are very different strokes.
It's most likely that the idiot electrician installed what he was told to do by an idiot engineer.

[roycv]

Hi tr7v8 thanks for that I will bear that in mind.
Hi Stan no offence taken I was an old style computer systems teckie where you never knew how the next peripheral would work.  I used to get sent on the obscure equipment courses, you name it I've seen it.

I would not dream of questioning a Qualified technician, it is the also rans one has sometimes to wonder about.  I recall the bad old days of the print unions when they tried to take charge of an extremely well known company's computer maintenance.  (think Rupert M).  I had fun thwarting them by going along with them, showing them the detail, offering to arrange the courses but when they saw what was involved they just faded away.

Many years ago I sat quietly in a Marks and Spencers store working out how to set up a a check out to read bar codes.  No one had heard of them before.  I was lucky to have been around when the accepted norms of today were still being worked out.  Main thing was that it was all enjoyable and I worked for several good managers.
I have always regarded the members of this forum with the respect they are due for ability to make and produce such great models.  Some declare their beginners status, even braver!  There are no trolls here.

But behind the research and interest there is always the enquiring mind and this was why I posted my problem where I knew I would find some good thinkers.
regards to you all
Roy

[tr7v8]

Hi tr7v8 thanks for that I will bear that in mind.
Hi Stan no offence taken I was an old style computer systems teckie where you never knew how the next peripheral would work.  I used to get sent on the obscure equipment courses, you name it I've seen it.

I would not dream of questioning a Qualified technician, it is the also rans one has sometimes to wonder about.  I recall the bad old days of the print unions when they tried to take charge of an extremely well known company's computer maintenance.  (think Rupert M).  I had fun thwarting them by going along with them, showing them the detail, offering to arrange the courses but when they saw what was involved they just faded away.

Roy sounds like we have similar backgrounds. I was a Senior Digital Equipment Company Engineer (DEC) for a long while. Also trained on some obscure stuff, was a Tape & disk & printer specialist for a lot of it.
Been there with print unions & others. Major supermarket chain was one. I trained 3 teams over a two day course each. They were like rabbits in the headlights.
As for the dodgy installs both were by qualified sparks. One was in this house where they'd drilled through a cable cover & into the cable for a rawlplug. The other was at a customer where we discovered they'd wired the  ring to the 6Amp breaker & the 32Amp breaker circuit to low power loop. 

[Monkeey]

Morning, this may help.


An RCD works by monitoring any current flow to earth, its cumulative, so each circuit may have a small leak which is no major problem but they all add up and cause the board RCD trip.  Heaters, PC power supplies, cooker rings are all prime suspects.  It is now possible to replace normal MCB's with ones that contain an RCD as well (called an RCBO), so each circuit is individually protected as opposed to one RCD that protects the whole board.  This is what I did.  Just my thoughts and experience.


https://www.screwfix.com/p/wylex-32a-30ma-sp-type-b-rcbo/39356


Paul

[grendel]

as a response to Stan, while I dont qualify as a competent person to do electrical installation, I am an assitant design engineer working for an electrical infrastructure provider ( we design what the electrician installs) as such I am aware of the theory and practice behind the electricity supply.
RCD's are designed to protect the human in the circuit, if you touch a live cable then enough residual current will be transmitted back to trip the panel, but the further you go from the panel - eg on an extension to the shed or garage, the less likely the possibility to trip. the rcd local to the device should trip first as this will see the residual current first, this tends to point the trip
 source away from the remote heater as that has its own local RCD, which should trip first.

[grendel]

Roy, I have a test plug that i purchased at lidls, you plug it in and it tells you if the socket is wired correctly, i mention this because another feature is an rcd testbutton, i was theorising if you had one of these you could plug it  in where the heater plugs in and press the test button, if the local rcd trips rather than the main one you will have proved the trip doesnt originate in your workshop

[roycv]

Hi grendel, so far the consumer unit has not tripped.  I will give it another day and then take the previous convector heater to the workshop and plug that in.
Thanks for the continuing interest.
Roy

[grendel]

I have a similar setup, my workshop is fed from a socket at the closest point in the house, i have an rcd unit plugged into the socket, then the workshop plugged into that, a while back I had the one tripping when I used a certain grinder, it turned out the earth pin had come disconnected in the plug for that, so it was tripping out the local rcd. this was when asking questions of my senior designers I found out about the distance being a factor in whether something will trip an rcd.

[HMS Invisible]

Roy, I have a test plug that i purchased at lidls, you plug it in and it tells you if the socket is wired correctly, i mention this because another feature is an rcd testbutton...

That is the same, basic pass/fail function as a 35 year old metrohm rccb tester with 4 test current settings.
If already wired correctly and to to be tested once , he may as well use resistors like Big Clive on youtube You have to be careful with mains voltage and quick as the resistor power loss is beyond the one or two watt continuous rating.
A 30mA AC RCD trip point is 27mA to 30mA.
Leakage measurement
The test rig in the youtube video has one turn and a clamp meter with a high sensitivity range but there is nothing to stop you coiling the earth loop into 20 spaced turns to get a reading with a normal, low sensitivity clamp meter.

[malcolmfrary]

In any system with more than one RDC in series, there will always be a winner that trips first.  Once the offending bit has been isolated the other will have no cause to trip.
RCDs can't directly measure the leakage current, they can only compare the current going one way on live with the current coming back via neutral.  The basic assumption is that whatever difference is leakage to ground.

[roycv]

Hi to all my fellow investigators.  With no heater connected it has not tripped.  I have this morning put the old covector heater 2KW in place to see what happens but the workshop is nice and warm now!  I checked the other heater's 13 amp plug and all connections tight and no whiskers of wire.
I have left the lights on as a tell to see if it all remains working.
I am learning more about RCD's from your posts so thanks.for the input.

Regards
Roy

[roycv]

Hi all, the investigation has been going on so that now I can say all the wiring involved and the additional RCD leading out to the workshop are all working.
I have had another heater in use and all OK.
This morning I connected in the usual oil filled radiator and there was a burning smell.  So I brought it into the house let it cool down and then opened it up to reveal the electrics.

Oh Woe! 

There is a chocolate box connector which may have developed a poor connection and caused heat from which there was a meltdown.  Just charred plastic and most of it gone. This must have been going on for a while well before my Smart meters were fitted. The mess was 'dug' out and the choc box connector replaced, wires cut back, and is being tested in my presence to make sure there was nothing else.

So well done to the trip!  May have saved the workshop from damage.
When confident I shall restore it into use.  Logically there was only ever one issue and that was the heater, the RCD trip just did its job.

Thank you to all contributors I learnt a lot and I hope all is now resolved.
Best regards
Roy