Need Earthing Rod For Shed ?

[tony.nickalls]

Hi,  After Electrican changed RCD spilt load consumer from MCB unit 7 years ago ,my house getting occasionally power cut about one every two weeks even since and even on dry day we sometime get power cut when we come home .we rely my neighbour to check in to keep my freezer going !! so this RCD replacement , that tell tale we have problem somewhere around the house ( my house 100 per cent rewired 15 years ago)

I am aware if that there it is 30 amp long single spur from spilt load RCD consumer unit in the house run through inside house into my brick shed and it is just attached to my house (like a garage) that if causing power cut in the house.??

In my brick shed there is small consumer unit of 63amp MCB. and should i have earthing rod in outside ?? or change RCD unit in the shed ??

Look forward to hearing for your help 

 Tony

 

[Blue Duck]

Isolate the shed supply does the rcd still trip?

 

[ProDave]

Yes as above. you have to find the CAUSE of the rcd tripping, not just make random changes to the wiring.

Get all your appliaces PA tested, one of them might be fauty, could even be the freezer.

 

[tony.nickalls]

When main RCD tripped in the house then i tripped all switches down then put back main RCD trip and trip all back, nothing trip back again ! sometime main RCD trip back again another 5 minute . ! faulty RCD trip ??

I like your photo Twatt Dave lol !

 

[ProDave]

By all means try if for a week or so with the shed turned off. but my money is on a faulty appliance still.

 

[tony.nickalls]

Will do now Many Thanks

 

[NozSpark]

So...to understand this correctly

You don't actually have a power cut do you, what you come home to is a tripped RCD and then have no power on your socket circuits?

Am I right?

and that you suspect that the RCD trips because of a possible fault somewhere on the shed circuit?

If I'm correct then you may be able to confirm that the shed circuit is in fact the culprit or you may not.

If I were you I'd get someone in.. they should be able to identify the faulty circuit pretty quickly and then they would have to narrow the fault down further.

But like Dave said....you may have a faulty appliance

 

[Doc Hudson]

If your property was fully rewired 15 years ago, it is probably about 5 years overdue for a full formal period inspection. (recommended intervals 10years or change of occupancy) I would think the best solution is to confirm all of the wiring is still electrically intact and all of the RCD's are tripping correctly, (not over sensitive). That combined with testing appliances as ProDave suggests. There are numerous probably causes of RCD's tripping and lots of things can deteriorate within an installations wiring over a 15 year timespan. Before doing any possible unnecessary work I would suggest inspection and investigations by a competent person with appropriate test meters.

Doc H.

 

[tony.nickalls]

 That right it only sockets circuits is the problem not the rest ( that why i have spilt load consumer unit with RCD that keep tripped ), i realised when i had RCD consumer unit changed during when i had new kitchen and dining extension i didn't have dishwasher and freezer that time and renew washing machine and t.v later , still the same problem ever since,  could be deteriorate with the wiring as you said Doc H,  i i'll wait see what happening with the shed as it switched off power at the moment . and feed cable for temporary light from inside house ! anyway i have tested with every single sockets with tester …. all passed !  I will narrow it , i let you know what happen next otherwise will call for a competent person. !

Many Thanks Tony

 

[Andy™]

if your switching it off via an MCB, then you wont be fully isolating the circuit, so if it is the shed thats the fault, it would still trip

calling a sparky may be the best option - they should be able to identify the faulty circuit in very little time

 

[NozSpark]

It sounds like you have a socket tester with a few LED Indicators to show polarity (BTW I've not seen one that can test for a N-E reverse)..... These testers cannot test for the kind of fault that the tripping RCD is seeing

Like I said before you need to get a competent electrician to test your installation and find the fault

 

[SPECIAL LOCATION]

 That right it only sockets circuits is the problem not the rest ( that why i have spilt load consumer unit with RCD that keep tripped ), i realised when i had RCD consumer unit changed during when i had new kitchen and dining extension i didn't have dishwasher and freezer that time and renew washing machine and t.v later , still the same problem ever since,  could be deteriorate with the wiring as you said Doc H,  i i'll wait see what happening with the shed as it switched off power at the moment . and feed cable for temporary light from inside house ! anyway i have tested with every single sockets with tester …. all passed !  I will narrow it , i let you know what happen next otherwise will call for a competent person. !

Many Thanks Tony

Hello tony.nickalls....

from reading your posts I think there are a few things which you don't actually appreciate or understand at the moment.... 

AND which could mean you waste time doing irrelevant tests that prove nothing...

to try and explain  (and expand a bit on Andy & Noz's comments above) ...

1/ In an ideal world where money is no object every circuit would have its own individual dedicated RCD...

2/ In the real world (due to the cost of RCDs) multiple circuits often share one RCD...

3/ With shared circuits on one RCD it can be very difficult to identify exactly which circuit is faulty...

4/ RCD's detect an imbalance between either live or neutral to earth...

5/ MCB's only disconnect the live....

6/ A circuit with a Neutral to Earth fault, that is switched OFF at the MCB.. can still cause an RCD to trip when power is flowing down other circuits that share the RCD... (This is because ALL of the neutrals and ALL of the Earths are still common together and the MCB does NOT disconcert the neutral...

7/ A plug-in socket tester will show a socket is wired correctly even if Neutral and Earth are touching

8/ A 30ma RCD will trip if neutral and earth have 7666ohms (230v / 30ma) or less between them.

You need to be doing some continuity tests and insulation resistance tests and some RCD trip time tests on all the circuits and RCD's to even stand a chance of trying to establish where the problem is actually coming from.....

Unless you have other information you are not telling us..

or if you can do IR, continuity & trip time tests.....

then I honestly think you are wasting time trying to figure it out yourself....

opcorn

 

[Andy™]

8/ A 30ma RCD will trip if neutral and earth have 7666ohms (230v / 30ma) or less between them.

but a 30mA RCD will usually trip around 22-24 mA so around 9000 ohms iirc

also, for the n-e short, it has to be much less, almost short circuit, since there is very little voltage between them

 

[binky]

if the tripping is random, and you can re-set circuits without RCD tripping out straight away, then my money is on a faulty appliance, and lamost certainly fridge / freezer / boiler as these are the only things normally left on all day and which can randomly cut in / out to cause random tripping.

Your RCD is working correctly, it is doing exactly what it should do, but if this probalem has been presisting for a while, and has tripped RCD many times, then it could have deteriorated and may be worth changing.

If you are fairly convinced the outside shed is the problem, it would be worth moving it onto a non-RCD protected MCB, and putting RCD in shed, or using an RCBO for that circuit (RCD combined with MCB) so that it isn't sharing RCD with rest of house. However the best way to proceed, as pointed out, is testing the socket ciruits first, as you could do the above and not achieve anything, though it would be better than your current set-up.

3rd option get some nice double pole RCBOs from SDS Dave, and swop out the MCBs. You may find tripping evaporates because of not sharing ciruits with other appliances - most appliances leak to earth these days, and the build up of leakage from numerous appliances can cause RCDs to trip, when something like a fridge turns on, leaks that extra bit and takes RCD over its limit. Electric turns off, fridge ( and other appliances) shuts down, you re-set RCD and all appears to be OK again for a while......

 

[tony.nickalls]

Thanks a lots mates , some things you said like..  wow to me..  not of kind my knowledge ! I just remember..  3 years ago i fixed extra socket (in total of two sockets) in the shed while this MCD 63 amp in shed switched off and i was weaving round the wire for my new 2nd sockets and in the house RCD tripped 3 times then stopped and ok till when i done !!. if that make sense to you if the shed is sound the problem.? anyway house power is still on since while shed if off at moment ! next step i will find pro electrician very soon. But all my appliances .. When he here will he find out which one is faulty ?

Thanks

 

[Blue Duck]

If the electrician you choose does portable appliance testing testing then they should be able to find the problem

Sounds like the problem my be in the shed?

 

[binky]

Thanks a lots mates , some things you said like..  wow to me..  not of kind my knowledge ! I just remember..  3 years ago i fixed extra socket (in total of two sockets) in the shed while this MCD 63 amp in shed switched off and i was weaving round the wire for my new 2nd sockets and in the house RCD tripped 3 times then stopped and ok till when i done !!. if that make sense to you if the shed is sound the problem.? anyway house power is still on since while shed if off at moment ! next step i will find pro electrician very soon. But all my appliances .. When he here will he find out which one is faulty ?

Thanks

did a similar thing many years ago before re-training as an electrician, couldn't understand why the RCD kept tripping with the leccy off :slap

is there any damp in the shed? large collection of spiders / woodlice? Could well be your problem rather than an appliance

 

[Blue Duck]

Had one a few weeks back, found a spiders nest in the back of a socket :| and another a fried mouse in the back of a cooker :|

Sensitive things these arsceedee's