A

alw94

I completed the wiring on an extension of some relatives of mine and certified it about 5 months ago. Now, the main part of the house has some old wiring and I have fixed, repaired and moved sockets and lights but I haven't carried out any testing on this side of the house. The extension wiring is mine from start to finish and is all checked out. I have just had a call to say that a week ago both RCDs tripped and that that since then the CB for downstairs lights won't re-set. Now, instead of phoning me, they contacted Southern Electric as they have one of those monthly service contracts. He has commented on the shower I fitted (9.5kw shower/10mm cable) being on a 50a CB. At the time I was looking for a 45a CB but, as far as I remember, Wyles don't do a 45a CB, so did a bit of checking and plumped for the 50a CB thinking that this and the 10mm cable would also allow for any changes in future. The guy from Southern Electric had to phone his boss who have recommended as 32a CB. This can't be right can it? Looking at other posts I think I'm on safe ground. Any comments from you folk?

Now, he hasn't checked anything else - actually, it's not clear at all just what he has done - but the downstairs lighting circuit still won't re-set. All I have done to this circuit before was to change a pendant and used this circuit for the smoke alarm in kitchen and hall. Considering that all was well for 5 months this problem has only occurred after both RCDs tripped. Could it be as simple are bulbs blown causing problems? I've asked them to switch all lights off, re-set CB and then go around switching on one room at a time but they are not even sure of some of the lights are on or off as they are dimmers. I live 200 miles away and they want me to go down to sort it out but am really pushed to find the time. Any helpful tips from you folks about assessing the possible problem before making the trip?

It, of course, is making me feel uneasy about whether I've done something wrong but short of not quite tightening wires up, I can't really see what. It doesn't help that it took 5 days for them to come to me. Instead they went to Southern Electric, an apprentice friend of their son and other people who all have a comment to make. When I first spoke to them they apparently had problems with sockets I fitted but I think we've got to the bottom of those and they are ok.
 
Cheers. You wouldn't believe some of the problems I've had with the builder they used removing parts of the circuit and plasterboarding over switches! I'm always that last to know about problems and I spent half my time fixing bits and pieces for them instead of installing the testing the extension. There is always something else. Oh yeah, what about them removing sockets and leaving earth off...and neutrals...and a live! I had to quickly fix one ring main before my assessment. Not a good start. It's been a proper pain in the arse. Ferking family...
 
10mm twin and earth depending on the installation method ie clipped direct can be rated at 63 amps check the current capability of the cable in the way that it's installed a 50 amp breaker may be fine, regardless of the power of the shower being less
indeed but if you cant verefy the installation method for the whole run......better to err on the side of safety here and as has been mentioned here already....noware near the actual current draw.....40A good......
 
indeed but if you cant verefy the installation method for the whole run......better to err on the side of safety here and as has been mentioned here already....noware near the actual current draw.....40A good......

Yeah I agree, but what I was getting at was southern electric pointing out this as wrong... Could be completely fine and I'm sure the op would have checked the installed cable or actually installed it before putting on a 50amp
 
Cheers. You wouldn't believe some of the problems I've had with the builder they used removing parts of the circuit and plasterboarding over switches! I'm always that last to know about problems and I spent half my time fixing bits and pieces for them instead of installing the testing the extension. There is always something else. Oh yeah, what about them removing sockets and leaving earth off...and neutrals...and a live! I had to quickly fix one ring main before my assessment. Not a good start. It's been a proper pain in the arse. Ferking family...
well the point here is you identified 1s and dealt with em then didn`t you...
 
Prior to starting I did the ze & zs on the system but didn't check the individual circuits. The changes I made to the main house was new pendants, socket, moved socket & cooker switch from directly above cooker. I haven't extended or anything. I get it though - full checking would've highlighted possible problem areas. I'm just ****ed at having to go at short-notice to fix it when if they had told me I could've gone at the weekend. I still would've been ****ed but it would've been better timing. The lack of notice has been a feature though as whenever the builder has been plastering, removing switches etc I'll turn up and they'll tell me something somewhere is not working. I'll try and sort it before getting on with what I'm there for. How about the guy rendering around the lights and sockets outside instead of removing and re-fitting? Anyway, moan over. I'm just tried to help them.

I've checked my notes and went for the 50a as it is a 10.5kw shower. I fitted the the shower installation and it is clipped direct but didn't think there was any diversity allowed on a shower. Which is why plumped for the 50a. I get the full power not being likely for too long.
 
what book you using for you max Zs tables?...osg?...brb/bgb?.......as their both different.....one of em need a correction factor appled.....and this could affect whether the circuit Zs values obtained complied or not.......
 
so is this "new install" fed from existing final circuit/s broken into....or does it come directly from the existing board?......or another board fitted to comply with the 17th edition?..........
 
  • Like
Reactions: 1 person
What were the earthing and bonding arrangements here like?...up to the current requirements?.....You check that before carrying out any new work......
 
New installation added for the extension of the house. No previously installed circuits extended. What was in previous is still in unchanged apart from the d/s light which I connected the smoke alarms into that is all. New board fitted to 17th and tested. Basic checks first time (2yrs ago) met osg. I know I need to go back and find on what the problem is and a new set of results for all circuits is needed. To make sure and to cover old and new.
 
Cheers glenn.

Re. the shower - the 40a is ok for the 9.5kw but I've fitted the 10.5kw and used the 50a. Should I fit the 40a and assume that diversity takes care of the rest.
 
10.5KW...so thats 45.65A....so call it 46A.......your 10mm cable can carry 64A method c (clipped direct)....so in this case go for a 50A MCB...but check the install method first..(how the cable`s been run)...through insulation for instance as that will knock down the CCC..........
 

Similar threads

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way 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

Daily, weekly or monthly email

Thread Information

Title
A lighting CB wont re-set and shower CB rating query.
Prefix
N/A
Forum
Australia
Start date
Last reply date
Replies
43
Unsolved
--

Advert

Thread statistics

Created
alw94,
Last reply from
GLENNSPARK,
Replies
43
Views
5,780

Advert