A lighting CB wont re-set and shower CB rating query.

[alw94]

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...

 

[GLENNSPARK]

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......

 

[keniff]

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

 

[GLENNSPARK]

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...

 

[Hawk81]

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 tested any of it

why did you not test the circuits you altered?

 

[alw94]

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.

 

[GLENNSPARK]

so if you wern`t testing individual circuits....how did you get a Zs for em?

 

[GLENNSPARK]

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.......

 

[alw94]

OSG for the table but I didn't fit the circuit that won't re-set. I checked the r1 r2 ir on the new installation but not the existing.

 

[GLENNSPARK]

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?..........

 

[GLENNSPARK]

What were the earthing and bonding arrangements here like?...up to the current requirements?.....You check that before carrying out any new work......

 

[alw94]

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.

 

[GLENNSPARK]

Get an IR done first on that offending circuit and sort that one out.....then do your tests after you have inspected .........

 

[tantrumelectric]

its lamps not bulbs, cables not wires....................

MCB's are to protect the cable

 

[alw94]

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.

 

[keniff]

its lamps not bulbs, cables not wires....................

MCB's are to protect the cable

Agree. So forget the shower and diversity just suit the mcb to the cable and instalation method

 

[alw94]

ok cheers

 

[GLENNSPARK]

dont even know the length of run for the shower here......

 

[alw94]

it's only about 7-8 mtrs.

 

[GLENNSPARK]

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..........