New wiring - need some help please

[pablo]

Hello!

First of all i am not an electrician but need some help on how to progress with a problem i have. I apologise in advance if i'm not using the right lingo but i hope i'm making everything clear.

We've just had an extension of our lounge completed. Electrical fittings were 6 double plugs on a new ringmain and several spotlights all controlled by 3x 3gang dimmer

Dimmer switches:

Dimmer 1
a) controls a single GU10 50W Spotlight
b) controls 2 GU10 50W spotlights
c) controls a set of 4 50W GU10 spotlights

Dimmer 2
a) controls a set of 4 50W spotlights
b) controls a set of 4 50W spotlights
c) controls 1 GU10 50W spotlights

Dimmer 3
a) controls 1 single GU10 Spotlight
b) controls 1 single GU10 Spotlight
c) controls 2 GU10 50W spotlights

The dimmers are getplc and rated at 60-300W per gang.

Every now and then we hear a loud 'bang' that appears to come from either the ceiling or behind a wall's plasterboard. A millisecond before the bang the lights (everywhere in the
house) dim for a fraction of a second. This could occur once every few hours or even a few times within the space of a few seconds. It also occurs when all lights in the lounge are off and also when there is nothing plugged into the lounge sockets.

The work was carried out by a building company and further inspected by another electrician. He performed wiring tests on all sockets, lights and fusebox and found no problem and he is equally confused. Unfortunately we had no 'bang' while
he was here which may have helped in diagnosis. We have the electrical installation certificate.

The only compatability issue here is the dimmer controls that control only one spotlight at 50W, rather than the minimum of 60W. The electrician said that the problem we have would not be caused by not meeting this threshold; the said light would only flicker.

So we are completely stumped and require opinions assistance from experts!!

Hope you can help.


Paul

 

[jeremy]

Just picked this up on recent thread thanx to sivoodoo. If a dimmer allows it to switch 300 of the w's then if you add all the w's up and they add up to more than 300 of those pesky w's then there may be trouble ahead!

 

[coxy]

Hi,
If correct details given do you realise your dimmers are overloaded !!!!!!

 

[bonjovi]

in my opinion i would ask another spark to test your property or two more if he cant find it
the reason for this is although your proberly happy with the spark who tested your property in reality with years of experience i have found most testers although they have passed their testing exam (i myself have tested lots in the passed without qualifacations and didnt really know what results i was expected to find just recorded them on paper and went on my way as instructed by the company i was working for ) dont know what their doing
this fault should be found on a insulation resistance test so my advice is to contact a company tell them of your problem and ask them to send a compatent tester with
surficiant knowledge to rectify your fault

 

[Shocking]

how is the W`s over on the dimmers the biggest load is dimmer 2 (b) 4 x 50 w = 200 W`s and there are 3 x 3 gang dimmers at >300 W`s each 9 in total



ps Dont you just hate it when they dont post the answer or what the fault was and was it fixed? come on Pablo

 

[Kris]

I have come across this once befor one of the blokes I used to work with did a job a few years back and didn't use any capping, the plasterer nicked the cable when he did the render (for that stuff to dry properly it takes ages) and what was happening was the moisture was building up until it was enough to create a short from L-N ***BANG*** the short then dried up the moisture and all was fine for a couple of hours until it built up again!

So my question is have you had the walls plastered?