RCD trips

[DAVE E C]

Hi, I have just had a new consumer unit fitted, its a split load unit, my problem is that the lighting circuit trips when i switch on two particular lights ( but not every time ).
The lights have round transformers fitted to them and are pretty heavy units, the main light has 16 x 10w halagon bulbs and the other has 12 x 20w bulbs, they are switched seperatly but from the same bank of 3 switches receiving power from the same cable.

Can anyone shed some light on the cause.

 

[topquark]

Thought it sounded a bit like a spanish toreador

 

[DAVE E C]

Firstly i would like to thank everyone who has replied to this thread, its nice to find people taking an interest in others problems.
The electrician is qualified to self certificate for both 17th IEE regs and part P Building regs but appears not to have checked the system befire changing the unit.
The work he quoted for was.
Supply and install a 40A mcb and 10mm T&E cable to a 45A switch outside bathroom and connect to customers shower unit.
Cut a 100mm vent through wall insert flue with eeterior vent and wire in customers own extractor fan, route a new switch to the outside wall of bathroom.
Adapt the lighting circuit to the bathroom and fit 6 customers supplied down lights and switching.
Run a loop cable to connect customers mirror light.
Run a loop to a fused connection to supply customers towel warmer.
Take out 2 consumer units and fit customers unit.
To test and inspect instalation as per 17th IEE and provide certification
All works to comply with building regs and 17th IEE regs.
To provide Part P certification as required.
I would be interested as to how much other electricians would have charged for this work.
ANSWERS PLEASE.

 

[davelerave]

i'd assume if the drinks not confusing me'

that it's magnetising current as bugsysaid


they don't trip every time on magnetic trafos-depends on what part of cycle

 

[davelerave]

as bugsy said the c type (if Zs allows)will prob cure it

-if wiring checks out ok

 

[mozzo]

The work he quoted for was.
Supply and install a 40A mcb and 10mm T&E cable to a 45A switch outside bathroom and connect to customers shower unit.
Cut a 100mm vent through wall insert flue with eeterior vent and wire in customers own extractor fan, route a new switch to the outside wall of bathroom.
Adapt the lighting circuit to the bathroom and fit 6 customers supplied down lights and switching.
Run a loop cable to connect customers mirror light.
Run a loop to a fused connection to supply customers towel warmer.
Take out 2 consumer units and fit customers unit.

There is a lot of work and the cost does depend on difficulty /accessibility and also if chasing is required for various cable runs.
To do a consumer unit change properly especially if old wires and 2x old rewirable fuse boards are in play, I would conduct a fulls days test first so that your know if there are any issues such as someone taping off from lights to create a 13a socket etc etc. Full periodic plus any other test deemed neseccary on first day. If major issues are discovered consult with client before changing consumer unit. Change consumer unit and test on second day. Shower cable installation is another day or 1.5 day depending. extractor fan and wiring 1 day. 6 down lights 4hrs. Lets say 5 days labour maybe at £200 day rate then materials £160 for 10mm cable and siwitches. lets round up to £1200 and 5 days work

 

[mozzo]

I would say bear in mind that a consumer unit change can be £500 - £750 typicially on it own, therefore a day rate charge is far cheaper regardless of the work involved.

 

[DAVE E C]

Thanks mozzo for the reply.
The two units removed were, 1. night store fuse box that had been disconnected by local energy company some years ago, the box was removed by electrician and cables cut right back. 2. fuse box with 6 fuses. accessibility could not be better, old tiles and plasterboard removed from 4 walls and ceiling taken down to expose all studwork, fuse box / new unit located in room immediatly below and part of floor removed to expose cables through ceiling below. We deceided not to have an electric shower afterall so no 10mm cable or switch or labour. So it ended up all cables run through drilled holes in studwork and connected to new unit through existing ring mains.

 

[ukpablo]

IM sure the price was reasonable as you agreed to the work to be carried out.
With regards to the problem, the spark in question has returned and although has not rectified the problem as of yet is making an effort to get to the bottom of it. Some faults can be easy to find and others unfortunately can baffle the best of minds! Im sure that talking to the spark and mentioning some of the comments from this thread may help in resolving the situation. With regards to pricing of work, different areas of the country dictate different prices and is a hard one to get spot on. As long as the person doing the work is registered and insured, u should have nothing to worry about except that lovely wooden floor staying in one piece!!!
good luck with fixing the problem, and just a thought but try changing the light fittings if all else fails before lifting the floor to rulr out thr transformers?!