Warmup Underfloor heating issue

[kerching]

actually was considering replacing the wall fuse spurs with ones with RCDs, to see if prevented the unit tripping,

Won't work,as both will trip

 

[carter69]

I think you're looking at damp ingress.

missed this

yes this has been my thinking, the question is how, where, why and maybe the proverbial needle in haystack. Anyway going for the EICR and hopefully will find the root of the issue 

 

[ProDave]

As others keep on trying to tell you, just switching off the odd circuit here and there is not the way to find the fault.

A competent electrician will have an insulation tester that will find leakage faults by dead testing the circuits one at a time.  And it may be multiple faults causing the issue not just one.  If the last "electrician" did not do that them strike him off your list.  Keep calling others until you find one that gives a sensible reply when you say "I might have an earth leakage fault"

This sort of fault is nigh on impossible to diagnose on a forum, you need to be there with the right test gear and knowledge to use it.  Sadly a lot of "electricians" particularly ones that do kitchens, don't seem to have the equipment or skills.

 

[Murdoch]

Be very careful selecting a person and the scope of your EICR , or you might as well set fire to a pile of £10 notes

 

[carter69]

Be very careful selecting a person and the scope of your EICR , or you might as well set fire to a pile of £10 notes

Thanks, how should I specify the scope I want covered and ensure its thorough enough without being over the top and flushing money away

Realise there's no one price fits all for something like this as every property is different with regards to size, its electrical complexity, etc but also don't want to pay unnecessarily 

 

[Murdoch]

I'm not sure an eicr is the correct route.

Investigating the tripping is more important imho

 

[carter69]

I'm not sure an eicr is the correct route.

Investigating the tripping is more important imho

Wouldn't the EICR pick up and hopefully find root of the tripping though?

 

[Murdoch]

Wouldn't the EICR pick up and hopefully find root of the tripping though?

If you are very lucky it may report low insulation resistance in the property and it would be coded C2 but it wouldn't find and resolve it

Unless you give the spark a blank cheque to report, locate and fix.

Sorry if this isn't what you want to hear, 

 

[carter69]

If you are very lucky it may report low insulation resistance in the property and it would be coded C2 but it wouldn't find and resolve it

Unless you give the spark a blank cheque to report, locate and fix.

Sorry if this isn't what you want to hear, 

ok, so to revert back to my issue. what would you suggest I ask of my electrician to find the root of the intermittent issue given  it may not present itself when they come

 

[Murdoch]

ok, so to revert back to my issue. what would you suggest I ask of my electrician to find the root of the intermittent issue given  it may not present itself when they come

That unfortunately is the position you are in.

Houses are like modern cars, a devil to fault find and fix.

 

[carter69]

That unfortunately is the position you are in.

Houses are like modern cars, a devil to fault find and fix.

So need to start somewhere and from other's suggestions no harm with EICR to see if any obvious issues with the system

 

[ProDave]

I share the view that inviting an EICR is likely to invite all sorts of faults and recommendations not directly related to your fault.

I would just get an electrician to solve the RCD tripping. That will involve some testing of the circuits and testing the RCD itself, that is all.

By the way what sort of house old or new etc.

 

[carter69]

I share the view that inviting an EICR is likely to invite all sorts of faults and recommendations not directly related to your fault.

I would just get an electrician to solve the RCD tripping. That will involve some testing of the circuits and testing the RCD itself, that is all.

By the way what sort of house old or new etc.

New house, 15 yeas old

Fingers crossed when electrician comes the system is having one of the days it is tripping so can see it for himself rather than take my word that there is an issue. Already explained the problem and if doesnt trip i dont think I would be wasting their time, my time or the money for the sake of it

 

[Geoff1946]

New house, 15 yeas old

Fingers crossed when electrician comes the system is having one of the days it is tripping so can see it for himself rather than take my word that there is an issue. Already explained the problem and if doesnt trip i dont think I would be wasting their time, my time or the money for the sake of it

Don't be too pessimistic. From what I'm reading I suspect you have an earth leakage fault somewhere. Probably neutral to earth. It could be water in an outside light, deteriorating element in any heating device, or many other faults, or a combination of two or more, but NOT difficult to detect with test gear, and not too difficult to trace by a skilled electrician. The variability you observe is most likely load dependant, rather than a manifestation of Sod's Law. For instance your UF heating WILL draw more current when it's cold, but that could be a complete red herring if the fault is elsewhere, such in your cooker, immersion heater, etc, etc. 

 

[binky]

random trip times and cold weather. Too me that would suggest a build up of earth leakages with something pushing it over the limit when cold. Cold coincides with condensation and damp, so could well be an outside light or socket on an outside wall??? So when cold, earth leakage is higher and UFH or another appliance(s) is taking the RCD over it's limit - old favourite for randon trip times is always a fridge or freezer.  It is alwasy hard to find these earth leakages, so I would suggest another course(s) of action:-

1/ get that old board replaced with RCBO unit

2/ install mini board for UFH alone (NB must have RCD protection). 

3/ move UFH to newer board if it has space.

I converted my own board to RCBOs a few years ago to avoid screams from wife every Xmas morning. We have a double oven, range cooker, with one oven only ever being used at Xmas. Every year it tripped the shared RCD and caused mayhem. Unused ovens tend to get a bit of damp in the insulation which can be overcome by gently heating it up from a low level heat, so every Xmas morning this is what I ended up doing. After converting to RCBOs, the problem 'evaporated' ,. Instead of having 30mA shared across several ccts, I now have 30mA for each cct, (so about 180mA in total) so the system is much more relaible and stable and 'Peace on Earth' abounds Xmas morning  :^O  

 

[SPECIAL LOCATION]

Ok...  

So I may have missed one or two points after SKIP reading THOUROUGHLY this thread....

But as I see it....     we have....

{a} 1x RCD protecting a Stupidly designed arrangement of final circuits..  [unlikely to be a competent electricians work]

{b} An intermittent fault tripping an RCD that could be triggered by any combination of one or more circuits...   [so far UNPROVEN]

{c} No current, recent, {original} test schedules, certificates, documentation of any kind relating to the installation circuit composition.

{d} Inconvenience when tripping occurs and NO facts established to isolate any items out of the equation!

SO....    :C

BACK-TO-BASICS, fault finding for Idjuts..

1/ Assume nothing..

2/ Don't confuse yourself by forgetting that Neutrals and Earths are ALL still connected  even with the MCB switched off...  [AKA single pole isolation NOT double pole]

3/ Consider EVERY related circuit to be faulty until you have proven otherwise..

4/ Only discount items that have been proved to be unrelated..

Otherwise we are using the pi55ing in the wind methodology...

where it could all just end up leaving a nasty mess down your trouser leg!!!!!!!!!!!!!!!!!!!!!!

Guinness

p.s.

Is an 80A rated RCD suitable for that number of final circuits????????????????????    

 

[carter69]

Thanks all. So in summary, guess the issue is some neutral  to earth leakage which is more highlighted with certain weather temperatures and pushes the board beyond limit when both UF zones are powered on. So could be something like the garden socket getting condensation when cold/damp outside and triggering - not saying its that, just as an example

Electrician coming next week and hopefully the leak gets sourced. 

 

[ProDave]

Do let us know what he finds.

The important thing to remember is I am 99% certain the fault is there all the time, and it is a case of differing conditions and loads sometimes make it trip, but even when the rcd is not tripping there will be some leakage so I am sure so he will be able to find the fault(s)

It is not a case of the fault has gone away when it is not tripping and he won't be able to find anything.

The reason I asked about the house was recently I had a similar thing, found the leakage was on one ring final, and tracked it down to 2 sockets on one wall that were literally dripping wet with condensation.  It was an old stone cottage with no insulation and severe damp problems.  I replaced the 2 sockets and all was well, for now, until these too become saturated with condensation as the winter gets colder.

 

[Evans Electric]

no harm with EICR to see if any obvious issues with the system

Don't bother with the EICR  ...concentrate on the tripping problem .       First thing to do is to run  tests on the RCD   to ensure it's not "Nuisance " tripping .  

Then identify the level of current flowing to earth across ALL those circuits  protected. 

I see from your picture  you have two circuits switched out  ( That garden pump could have been high on the list !)     Then you have no less than five ring mains  PLUS the UFH  to check .  All need to be ruled out . 

I think there may be some earth leakage / damp ,  on your heating mats when cold  ..possibly... which disappears when warm  ... insulation readings when COLD  ,  then WARM  will be interesting .    

 

[Doc Hudson]

With regards to inspection, never I suspect. The house is around 15 years old, the kitchen was replaced 3 years ago when the underfloor heating was installed and the electrics were wired up. I've never heard of having reports on household electrics.

Don't bother with the EICR  ...concentrate on the tripping problem .      

I find it quite interesting how a few others have suggested an EICR is not important. Whilst I know they are not compulsory, yet BS7617 does recommend 10year or change of occupancy.  I am curious to know how far overdue an inspection, would an installation need to be, before you recommended a customer organised a periodic inspection at their earliest convenience? Or do you never suggest installations are routinely checked for any signs of deterioration?

Any intermittent fault, may or may-not be located during a single visit, in some cases they can take multiple visits. But even if the fault was identified and fixed within a short time on a single visit, according to the OP, the installation is still 15+ years old, with no current test readings, or circuit schedule information. So as I read things, wiring reg's would still be recommending it is due to be inspected either way, fault or no fault.

The option of converting the board to RCBO's has also been mentioned, which would be a vast improvement, but again requires all the circuits you are converting to be tested, unless someone is advocating just swap the protective devices with no certificates issued?

It is not uncommon for fuse boxes to be labelled incorrectly, or for customers to have no idea about exactly which accessories are connected to each circuit, or if any circuits are broken or bridged at any point, or the overall condition of the cable insulation, or numerous other factors that could have implications upon an intermittent fault. Not sure how you identify any of these if just given a vague remit to "find the fault". If you don't find a cause at what point do you decide you have finished your "fault finding"?  (It is also feasible that there is no single fault at all, it could be four individual items that all have 8ma of natural leakage and it is only when 3 or 4 of them are on together that its trips?).

To have any realistic idea about all possible causes for your RCD tripping you need to have a clear understanding of the composition of the circuits supplied through that RCD. Without any circuit schedule documentation, I know I would find that a bit tricky. Some testing required during fault investigation for this tripping problem, would be identical to the testing required during an EICR. There is quite an overlap, especially with a RCD supplying 8 circuits! And lets also not forget that any periodic inspection has an agreed extent and limitations with the client. So you may as well document any test readings and results measured during fault finding onto an EICR rather than just scribbling them on a bit of scrap paper.

Doc H.