nuisence tripping rcd

[kanewesley]

united kingdom...yorkshire

I rent a semi detached house out which was built 1970's

With the tenancy just changed i thought i would change the original fuse box to a modern one with rcd's and mcb's before he went in.

Even though there is no legal obligation to do so and the wiring is still good I did it.

I had loads of tripping probs when first installed as the maze of wiring which has evolved around the house probably had neutrals crossed (split C/U with 2 x rcd;s)

Finally got this all sorted and had the house EICR checked sucessfully.

The tenant has now been in a month and he informed me 2 days ago his sockets were tripping the rcd for that particular bank of mcb's.

I temporarily replaced the affected rcd with a double pole MCB and all was fine.

So with everything umplugged and the rcd back in, i attempted to find the offfending socket or piece of wiring what was tripping the rcd.

After 7 hours or disconnecting, testing, carpets up, floorboards up, decor damage around sockets I was getting nowhere.

AS the wiring to the house has evolved over time it was impossible to know which cable ran where so to get him back online and get the sockets, floorboards and carpets back before it got dark, I put in the 60A double pole mcb back in in place of the rcd.which was supplying that particular side of the C/U.



The rcd is 63A / 30mA.

Can I leave it like this with a 60A MCB in place of the rcd which supplied the sockets?

If I hadnt changed the fusebox for a newer C/U this problem would never have arose.

I understand rcd protection regulation applies to rewires and new installations.

This house has not been rewired nor is it a new installation so as the regulation is not retrospective can i leave the MCB in in place of the rcd.

At least it is better than it was as there are now mcb's rather than fuses and individual circuits now have their own MCB.

Another question, is it also an option to give rcd protection by installing say a 100mA rcd which is not as sensitive....this may hold.

To rive up every carpet and floorbaord in the house and move every bed and piece of furniture trying to physically follow the cabling is a mountain of work and disruption when fitting an mcb will stop this nuisence tripping.....

I wish I had left the old fusebox in.

Advice would be gratefully received.

Thank You

John

 

[pc1966]

It sounds like you have the background to do this, but are lacking either the test equipment or logical process to find the fault.

First step (at least for me) is you do an IR test on the circuit(s) on the offending RCD with everything unplugged / off. Checking both L to E and N to E, or do L+N to E if you are looking for a fast and safe check if there are LED lights, etc.

Also worth an early check is to see what current the RCD is actually tripping at, but a sensitive-fault RCD is not such a likely reason in practice.

If those test shows nothing suspicious then put the circuit back on and clamp the RCD lines with a meter that can read down to 10mA or less and see if the RCD has any legitimate reason to trip.

If nothing shows up then get all the appliances plugged back in and see if any of them has raised the leakage current to a point near the 15mA start of trip region.

 

[Craighrvy]

Having all the qualifications you have, I cant believe your asking if you can replace an rcd with a mcb if it's tripping and just leave it, why would you do that, especially in a place you are renting out. If its double pole it's more than likely just a linked main switch and not an mcb so it won't be protecting the circuits at all. Especially if it is supplying socket outlets you will never achieve the required disconnection times which is the whole point of changing the consumer unit in the first place. Your meant to be making the installation safer right? Your actually creating a bigger potential problem if you do that. As your the landlord and you installed it, it's on you to rectify it now. Don't think I would be able to sleep at night personally. I suggest dusting off the old insulation resistance tester and bell out all the legs of the ring circuit. You won't necessarily have to lift boards up if you can test it adequately. You say you found shared neutrals, how did you rectify that? Are you sure it's not something switching in on another circuit, are you sure it's not something which is plugged in?
If you had tested the installation before installing you would have found these faults before energising. That is the reason why we have a sequence of testing
All the qualifications doesn't mean you are competent to install in a domestic property. You should be notifying building control if doing it yourself and that will cost you the best part of £500 so I bet you haven't done that, so much more cost effictive to get a part p registered sparky to do it for you.

 

[nicebutdim]

When an installation is upgraded and becomes compliant with current regulations are there any circumstances where it is deemed acceptable to remove certain aspects of that upgrade and revert back to compliance with an earlier edition of the wiring regulations?

I don't know the answer, but I'd be amazed if this was considered to be appropriate given the safety implications.

 

[David Prosser]

When an installation is upgraded and becomes compliant with current regulations are there any circumstances where it is deemed acceptable to remove certain aspects of that upgrade and revert back to compliance with an earlier edition of the wiring regulations?

I don't know the answer, but I'd be amazed if this was considered to be appropriate given the safety implications.

In short no!

 

[nicebutdim]

In short no!

That seemed like the logical answer, but thought it was better to ask than to assume.

 

[Grant1987]

When an installation is upgraded and becomes compliant with current regulations are there any circumstances where it is deemed acceptable to remove certain aspects of that upgrade and revert back to compliance with an earlier edition of the wiring regulations?

I don't know the answer, but I'd be amazed if this was considered to be appropriate given the safety implications.

Simple answer NO! The reason you are upgrading and ensuring the installation is compliant with current regulations is because it makes the property safer (As long as you know what you’re doing) obviously changing from an old fuseboard which offers no additional protection always inherits the chance of rcd tripping but you should be capable of fault finding If you’re changing consumer units although many aren’t. I’m often called out to fault find when sparks can’t fault find

 

[goasis]

Mcb's = O/L trip.

RCD's = Earth leakage trip activated by an imbalance in the current flow between ph and N conductors detected by a torroid Tx, amplified and mechanically trip the RCD

MCB's same job as Fuses but with better tripping characteristics dependant on type (ie D, C. B) with regards to impedance of circuit.
Previous consumer unit, meal clad with rewirable fuses.
No obligation to replace the fuse box as it was in good condition as was the wiring in it ....and installed under the regulations at the time of installation.
Change of C/U = advisory only....NOT a legal obligation.
Progressive accumulative earth leakage currents totalling 22 mA....enough to trip the RCD.
Earth leakage currents checked with MEGGER DCM305E Clamp Meter.

Retired electrician ( just ) of 45 years
BTEC National in Electrical Engineering
BTEC national in Practical Electronics
Full 4 year apprenticeship. followed by 45 years of electrical engineering.
Earth leakage detection sometimes had to be adjusted due to damp in walls of substations causing tracking to earth and causing nuscience tripping where the environment couldn't be improved.
New fuse box checked and tested durin EICR check detailing the installation was safe and correct.
leakage currents appeared after.
If fuse box had not been changed, this issue would never have arisen.
The circuit in question is not simply an upstairs or downstairs ring which can be followed round the house but has one ring feeding both floors with radials spurred off it in every direction, and without out ripping every floorboard up in the house and every carpet....is impossible to determine the cable runs.

Worked on, Isolated for others as a supervisory electrician on 3 PH AC distribution systems from 110v AC up to 6.6KV (rarely but experience on 11KV

Completed a 16th edition course many years ago.

The consumer unit CAN be changed as long as it is inspected by a part P registered installer before energising.

One can also work on ones own gas installations legally even though not gas safe registered.
Al the regulation states is one must be "competent", not gas safe registered and must not do any work for financial gain.
Competence is a combination of practical skill, training, knowledge and experience.

... An impressive cv..


What was the cause, and then solution to all the "tripping issues" you had initially when you changed the board?

 

[Jim_e_Jib]

This thread has to be a wind up?

If it's not, then the OP needs to get and wind up the handle on his Megger. And no, that's not a euphemism (but perhaps it should be).

 

[Vortigern]

The idea that you can only approach this problem by ripping up the carpets/floorboards fits with the experience you have detailed re your training/experience. I attended an extension half way through wiring with a view to finishing it off. It was done by an Electrical Engineer and although technically correct the installation approach was abysmal. Clearly you are not used to domestic type work.
So...it would be helpful for you to see that all the cable in the installation are accessible through the accessories i.e. sockets and ceiling roses etc. So if you proceed by removing the accessories (according to the circuit tripping) you can work on each separate cable, testing it to see if it is ok. Start by breaking the r.f.c. half way and test each side and see if there is any fault showing. Then work from there. I hope that is of help best of luck. I assume you have an MFT?

 

[pc1966]

You can hire MFT is you don't have one:

Electrical Installation Tester Hire

Electrical Installation Tester Hire: A range of earth testers, multifunction testers and installation test kits from Chauvin Arnoux, Megger and Metrel.

www.test-meter.co.uk

You can buy a low-current clamp ammeter for not much more:

Test Meter PRO TMP775 Earth Leakage Clamp Meter

Test Meter PRO TMP775 Earth Leakage Clamp Meter Specially designed for measuring AC earth leakage, the Test Meter PRO TMP775 Earth Leakage Clamp Meter offers a high resolution of 100µA and 3 ranges making it a great tool for general fault finding. Offering a low range of down to 200mA, a mid...

www.test-meter.co.uk

 

[DPG]

When an installation is upgraded and becomes compliant with current regulations are there any circumstances where it is deemed acceptable to remove certain aspects of that upgrade and revert back to compliance with an earlier edition of the wiring regulations?

I don't know the answer, but I'd be amazed if this was considered to be appropriate given the safety implications.

Not if it is done to hide a known fault. The fault itself means that the system inherently doesn't comply with any version of the regulations.

 

[GBDamo]

As I see it, if your tennant receives an serious injury or worse due to electrics in that property there is a very high liklihood you're going to do time.

How on earth can you stand up in court and say "yes I knew of the fault but took steps to hide it rather than rectify it"

Get the RCD back in.

Then get some data on the fault.

Is it permanently tripping?

Is it intermittently tripping?

If permanently tripping a spark, with the right test gear will track it down in a few hours or less.

If its intermittently tripping then you're going to have to work with your tenant to build a picture of whats causing it.

 

[nicebutdim]

I'm struggling to comprehend why anyone would want to hide a known fault, given the potential consequences of such a move. Genuinely stunned that someone with 45 years of industry experience is making the suggestion.

 

[Tony Reidy]

What do you suggest then.?

Ripping the house apart or putting the fusebox back in??

Find and fix fault like any decent electrician would

 

[DPG]

I'm struggling to comprehend why anyone would want to hide a known fault, given the potential consequences of such a move. Genuinely stunned that someone with 45 years of industry experience is making the suggestion.

Same here. Scary.