30ma rcd tripping after replacing consumer unit

M

muzza1

-
Hello all, how are you?
I often look on here but the time has come to ask for some advice!
Nearly finished some alterations in a customers Kithen, Dining room, Utility room and Garage. Approx 3 days work in total.
Anyway, after all 2nd fixed and new split load board installed pop goes the rcd! Proper annoying!
It was found that when the ch+hw boiler was switched on at the spur it tripped the 30ma rcd on the split load board, here we go, i thought :sad:
Explained to the customer the situation and after bypassing the rcd hopped in the van knowing Monday is going to be a headache, (can't stand fault finding!)
To try and cut a long story short, i was after some advice or ideas re how to get round this problem without some testing deep within the customers boiler etc with certification and notification in mind!

I hope i've made some sort of sense with my question!

Thanks for any help on this chaps.
 
Sort by date Sort by votes
muzza1 said:
Hello all, how are you?
I often look on here but the time has come to ask for some advice!
Nearly finished some alterations in a customers Kithen, Dining room, Utility room and Garage. Approx 3 days work in total.
Anyway, after all 2nd fixed and new split load board installed pop goes the rcd! Proper annoying!
It was found that when the ch+hw boiler was switched on at the spur it tripped the 30ma rcd on the split load board, here we go, i thought :sad:
Explained to the customer the situation and after bypassing the rcd hopped in the van knowing Monday is going to be a headache, (can't stand fault finding!)
To try and cut a long story short, i was after some advice or ideas re how to get round this problem without some testing deep within the customers boiler etc with certification and notification in mind!

I hope i've made some sort of sense with my question!

Thanks for any help on this chaps.
Click to expand...

Did you do any testing at all on your work before energising or just switch on and hope for the best ?
 
Upvote 0 Downvote
No testing then, serves you right, got yer tin hat on yet? and I was being kind, wait for the flak that's a coming your way
 
Upvote 0 Downvote
How exactly did you bypass the RCD?

There's hardly a lot of fault finding to be done is there, you already know it's in the boiler controls somewhere. It's hardly going to take you long to go through a domestic boiler circuit, is it a combi or heat only boiler?
If the fault proves to be internal to the boiler you'll be looking at getting a plumber out to fix it, and if you didn't have the sense to add a suitable disclaimer to the quote/contract then you might be paying for it.
 
Upvote 0 Downvote
i would disconnect heating system at fused spur, test up to that point prove all results, then speak with client about a fault on the heating system should the fault be after the fused spur. should it be on the supply up to fused spur then sort it out with them.

heating system if not a combi

disconnect boiler
disconnect pump wiring if not in boiler
IR test pump to earth
If pump IR test 0M ohms or there about's faulty pump
remove programmer cover bridge out L to no 3 & 4
turn up thermostat & cylinder Stat
IR test on secondary of the fused spur that you disconnected (boiler still not on circuit)
LN-E see if you have 0M ohms or close to it or clear
then open valve manually
same IR test
should show all the way to boiler.
if all clear above then put back together & would probably tell you that fault is in the boiler.

the above is for 230V controls & not low volt.
should you have a system's boiler you can probably unplug the pump & test it inside the boiler.

if you can't understand any of the above you are probably out of your depth & should consult your client to get someone in who can fault find on an electrical system.
the above is a basic heating system layout & may not cover every variation but it is a start for you.
good luck
 
Last edited:
Upvote 0 Downvote
Didn't do any testing prior to working on the ring main, getting complacent.
The original wiring is only approx 15 years old and not been messed about with so took it for granted that i shouldn't come across any problems.
After replacing board and identifying fault just supplied the ring from the 1st way next to the main switch, non rcd protected.
(Obviously i realise this can't be more than temporary)
To be honest i think i need to take a step back at the beginning of each job from now on and concentrate on doing some testing before getting the tools out and just cracking on! There's no way i can sign this job off until boiler fault is sorted, but as this spur is back to back with the cu any ideas on possibly feeding spur via 5amp radial non rcd protected from board.
It's a standard fully pumped ch system with 3 port etc.
I'll get cracking on with testing as much of the heating system as i can and hopefully will be able to crack it without calling a Boiler engineer, looks like being an interesting Monday morning!
 
Upvote 0 Downvote
You could possibly feed the boiler circuit from a non RCD circuit if certain criteria are met BUT that isn't an alternative to methodically finding and rectifying the fault. Check through the wiring associated with the boiler and controls and take nothing for granted - but also carry out the full testing on the ring just to make sure nothing is fooling you.
 
Upvote 0 Downvote
Yes, re energised the circuit which i should have tested first. Have you ever energised a circuit without testing it?

This ain't no wind up, just felt like seeking a bit of advice before going back to work tomorrow.
 
Upvote 0 Downvote
muzza1 said:
I guess that i've come a bit unstuck with the fault in the ch system being detected by the 30ma rcd. I'll get it sorted tomorrow.
Click to expand...


Yeah process of elimination shouldn't take to long to sort. If your not to familiar with heating wiring when you take the cover off the wiring centre take a picture on your phone before you start proding about in there so if you disconnect something or something pops out you have a reference to look at.
 
Upvote 0 Downvote
muzza1 said:
Yes, re energised the circuit which i should have tested first. Have you ever energised a circuit without testing it?

This ain't no wind up, just felt like seeking a bit of advice before going back to work tomorrow.
Click to expand...

I expect most Sparks have at sometime energised up a circuit before testing it, I expect it depends a bit on the size of the job. You're on a forum though Muzza where it's not really going to be something that many will admit to and also I believe the standard of work from forum members (and general interest in doing the job properly) may be higher than average.

I think I posted a thread back at the beginning of the forum about RCD tripping when I installed a new CU, I got a lot of stick (alot more than on this thread!), I ignored the bits that wern't helpful and I took on board the majority of the rest of the replies.

I can honestly say I will always do some basic testing of a CU prior to changing it now because that can save you a whole heap of trouble. If you quote for a CU change and then come across faults or Main bonding problems etc it would be unfair to expect the customer to pay, you could also get into a bit of a panic when it suddenly happens at 4pm when you're expecting to leave at 5!

Here are a couple of links that you may find useful:

http://www.electriciansforums.co.uk...ctrical-regulations/12971-cu-changes-you.html
View attachment CU check list.doc
 
Last edited:
Upvote 0 Downvote
uksparks said:
That's exactly what I do, I will have also carried out certain dead tests prior to agreeing to the work so i know what I'm in for.
Click to expand...


Yeah its the best way. Done a love job for a family member a few year ago and didn't carry out any pretesting. Changing the board testing each circuit as I go, come to the down stairs lighting and neutral is as flat as a fart to earth. Unscrewed all the ceiling roses...one cable in each fitting, unscrewed the switches...again one cable at the switches. Every lighting point had been JB'd before it was plaster boarded. It couldn't get much worse you would think...pulled the carpet back upstairs and its all tongue and groove boards . This was on a Saturday about 3 in the afternoon with no money in the job due to being close family. Since that day I've never changed a board without conducting some basic pre tests before hand.
 
Upvote 0 Downvote
I'll hold my hands up here and say I probably wouldn't have spotted this one until the circuit was renergised as I would have isolated the boiler before carrying out an IR test on the circuit. But I also would not have gone home without finding the fault as it doesn't take long to go through a boiler circuit and I don't want the liability of leaving a known fault in an installation.
Plus I have a very good working relationship with a local plumbing and heating company so can get pumps/valves/boiler internals fixed/replaced easily
 
Upvote 0 Downvote
muzza1 said:
Makes sense Dave.
Does anyone enjoy fault finding?
Click to expand...

I love it Muzza, you get to become a bit of a detective and have to start a logical process of elimination. However, I would not enjoy if I was under pressure so I try and plan and make time for the fault finding.
 
Upvote 0 Downvote
muzza1 said:
I'll try and make it theraputic next time i'm testing!

I'll let you know how i got on.
Click to expand...

That would be very interesting Muzza, you tend to get more help on this site if you become a bit more interactive.
 
Upvote 0 Downvote
happyhippydad said:
I love it Muzza, you get to become a bit of a detective and have to start a logical process of elimination. However, I would not enjoy if I was under pressure so I try and plan and make time for the fault finding.
Click to expand...

Me too, the satisfaction you get when you have tracked down that elusive neutral earth fault and you test the cable again and it's all good and then flick on the RCD and it holds. You think glass of wine when I get home to celebrate.

Then you go home really chuffed at fixing it and tell the Missus and go into massive detail about what the problem was and all she can say is "oh right"! Then the bubble is burst and your back to reality.:wink_smile:
 
Upvote 0 Downvote
haha, i know that feeling well!
Vitesse said:
Me too, the satisfaction you get when you have tracked down that elusive neutral earth fault and you test the cable again and it's all good and then flick on the RCD and it holds. You think glass of wine when I get home to celebrate.

Then you go home really chuffed at fixing it and tell the Missus and go into massive detail about what the problem was and all she can say is "oh right"! Then the bubble is burst and your back to reality.:wink_smile:
Click to expand...
 
Upvote 0 Downvote

Similar threads

impish15
Delayed tripping on RCD
Replies
4
Views
637
impish15
impish15
C
UK RCD issue baffling me
Replies
35
Views
2K
brianmoooore
B

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Green 2 Go Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses Heating 2 Go Electrician Workwear Supplier
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

Advert

YOUR Unread Posts

Daily, weekly or monthly email

Receive a daily, weekly, or monthly email containing a digest of new and recently updated threads.

Thread starter

M

muzza1

-
Joined
Location
london

Thread Information

Title
30ma rcd tripping after replacing consumer unit
Prefix
Forum
UK Electrical Forum
Start date
Last reply date
Replies
38
Unsolved
--

Thread Tags

Tags Tags
30ma after consumer consumer unit rcd rcd tripping replacing tripping unit

Advert

Thread statistics

Created
muzza1,
Last reply from
Octopus,
Replies
38
Views
4,979

Advert

TrueNAS JBOD Storage Server

Tilers | UK Tiling Forum | Tilers Forums | Find a Tiler
UK Tiling Forum by Tilers Forums UK
Plumbers Forums | Plumbing Advice | Gas Forum
Outside Play
Back
Top