Replaced light fitting - comes on then cuts out


Postby teakmk2 » Sun Mar 06, 2011 11:36 am

Hi

I've just moved into a new house and replaced a single plastic white rose pendant light with a 14 lamp (40W each lamp) chandelier. When power is supplied to the chandelier it comes on then suddenly cuts out.

The previous owner originally had a similar chandelier in place of the single white plastic rose fitting and installed the single rose fitting as he was taking the chandelier with him. It may be worth noting that the rose fitting did not work with its junction box broken and taped together. I have fitted a new junction box and tested the single rose fitting (prior to wiring the new chandelier) which appeared to worked fine.

When I first moved into the property I had this problem with another light fitting (6 lamp chandelier) cutting out, but it somehow sorted itself out.

The previous owner had a part P inspection/test for the electrical installation in November 2010.

Does anyone have any ideas why power is cutting out to the new chandelier? Could it be that the above light fittings I have had problems with are on the same 2 gang dimmer in the entrance hall then 2 gang on/off switch on upper landing?

Thanks
teakmk2
Posts: 5
Joined: Sun Mar 06, 2011 11:17 am

Sponsor

Simply Build It

Postby ericmark » Mon Mar 07, 2011 8:47 am

For a house with standard ceiling roses the maximum size of fuse or breaker is limited to 5/6 amp as that is maximum rating of the ceiling rose which acts as a junction box as well as holding lamp.

So 1380 watt is total for any lighting circuit. As standard 60W is considered normal for each ceiling rose so one could have 23 lights all switched on together without a problem. Most houses will not have this many so really one circuit will supply all lights.

Modern houses do tend to split the lights into two circuits to:-
(i) avoid hazards and minimize inconvenience in the event of a fault
(ii) facilitate safe inspection, testing and maintenance
(iii) take account of danger that may arise from the failure of a single circuit such as a lighting circuit
But older houses often have just one circuit. In houses since 2008 likely also protected by a RCD.

Once the DIY takes over however then the loading can become silly. 14 x 40W = 2.4A which leaves 3.6A for rest of house. A few more alterations like a few silly 50mm spot lights and very quickly one is over the limit and the trip will open.

Dimmer units also have a limited current and are normally given in watts. The wattage does vary but 560W is rather high and many will not work with that load.

As to the periodic inspection and testing well that has nothing to do with Part P. The original installer will need to issue an Installation Certificate and that will be submitted and a completion certificate the latter being Part P will be issued. But anyone can do an inspection and test and all that is really required is that the insurance company have insured the guy with professional indemnity insurance. Normal insurance taken out by electricians may not cover giving an opinion, often it only covers work done. And the periodic inspection report is an opinion. The report is based on some testing and a lot of observations but it is impossible to remove floor boards etc. so it is not 100% and it is possible that many faults will be missed. Like a car MOT it is mainly about safety and if the system is safe then it will pass. However it is very rare for any system to pass. In most cases faults will be found and will be categorised as to how important normally given a number 1 to 4 with a "1" being very dangerous and recommending power being switched off until corrected and "4" a warning that if you want future work doing some modifications may be required.

I would be uneasy with a report listing no defects on any house built before 2008 as the rules changed in 2008 which means most houses will have items which don't comply.

As a rule of thumb I would not fit any lamp fitting needing more than 100W without checking the system first including ratings of dimmer switches. When I wanted more light I used discharge lighting which means using so called energy saving bulbs although don't really save energy during the winter months. But 14 x 8W would reduce the load a lot. However very few will work with dimmer switches and normal in rest of Europe where discharge lights have been used for years is the 1/3 to 2/3 split so either 1/3 of bulbs lit, or 2/3 of bulbs lit, or all bulbs lit which gives a good 3 stage lighting control.

If there is a centre bulb then using a single tungsten bulb in centre give immediate light while rest warm up.
ericmark
Posts: 1193
Joined: Fri Oct 02, 2009 8:49 pm
Location: Mold, North Wales.


Postby teakmk2 » Mon Mar 07, 2011 1:13 pm

Thanks ericmark for your response.

When I mentioned the power cuts out, no fuses or RCD's trip - the chandelier just comes on for around 5 seconds then lamps go out. I can keep doing this with the same result.

As the lighting and power circuits for upstairs and downstairs are on different distribution board fuses and the distribution board trip switches don't trip, it sounds like it is the dimmer switch.

Would the following 2-gang 2-way dimmer be an adequate replacement:

Google "a5products.co.uk/index.php?main_page=product_info&products_id=1123"

Also thanks for info on electrical inspection.
teakmk2
Posts: 5
Joined: Sun Mar 06, 2011 11:17 am


Postby ericmark » Tue Mar 08, 2011 2:04 am

For a standard tungsten lamp yes 14 x 40W < 650W so it will work. However if you are using extra low voltage lamps then the dimmer needs to match inverter.
ericmark
Posts: 1193
Joined: Fri Oct 02, 2009 8:49 pm
Location: Mold, North Wales.


Postby kbrownie » Tue Mar 08, 2011 3:27 am

I assume it is only this fitting that is showing a problem.
It could well be the dimmer switch, try using the fitting with just one lamp(bulb) in and see what happens. it may improve depending if the dimmer still in good nick or not, but you could be overloading the dimmer as it stands at the moment what rating are the dimmer switches and what total output is on the fitting?
kbrownie
Posts: 1757
Joined: Mon Mar 05, 2007 9:36 pm


Postby teakmk2 » Tue Mar 08, 2011 12:15 pm

Thanks guys for response.

The existing switch is 3 gang double faceplate - 2 dimmers and one switch - each controlling a separate light fitting (14x40w lamp chandelier, 6x40w lamp chandelier and 1 fluorescent light box feature).

Do you guys know of a suitable 3 gang 2 way dimmer control or will I need to split into 2 separate faceplates?
teakmk2
Posts: 5
Joined: Sun Mar 06, 2011 11:17 am


Postby teakmk2 » Thu Mar 10, 2011 3:18 pm

Hi

I've done a bit of research into available dimmer switch modules and have come up with the following options: -

a. The existing 2gang 3module faceplate is an MK logic plus with 2no. dimmers and 1 switch. I am planning to replace a single dimmer switch with a 1000W or 630W third party dimmer module (Google "cpc.farnell.com/pro-elec/6sdp100/push-100-1000w-module/dp/PL09940" or "tlc-direct.co.uk/Products/DGSGD630.html" ). I am hoping the double sized module will fit in the middle module of the existing faceplate. Will I have any overheating problems in the existing back plate.
b. As a., but with 4 module faceplate.
c. Reduce wattage of chandelier light bulbs, say 14no. 25W instead (350W total) and replace dimmer module in a. with standard 400W dimmer switch.

Have you guys had any experience with using third party dimmer modules within MK faceplates?

Thanks
teakmk2
Posts: 5
Joined: Sun Mar 06, 2011 11:17 am


Postby ericmark » Thu Mar 10, 2011 4:47 pm

You will need what is called a grid switch. This has a number of parts
* Grid Plates - This is the face plate many different colours etc.
* Grid Frames - This holds the switches and sits behind the Grid Plate.
* Grid Switches - Many different types even with names on them.
* Grid Dimmers - Slide and knob 220W to 630W versions.
* Grid Boxes - Deeper than normal box
However the price is something else. Just the dimmer can cost £30 so for whole set-up you can easy pay £100 by time you have all the bits.

Try to google "mk grid switches" and you will see many versions switches can be as cheap as £1.84 so really depends on what you want.
ericmark
Posts: 1193
Joined: Fri Oct 02, 2009 8:49 pm
Location: Mold, North Wales.


Postby teakmk2 » Mon Mar 21, 2011 11:15 pm

Just thought I'd let you know that I decided to downgrade bulb wattage instead to 15W (from 40W). Works a dream. The light fitting is more than bright enough and this was by far the cheapest solution.

Thanks for the input guys.
teakmk2
Posts: 5
Joined: Sun Mar 06, 2011 11:17 am


Postby jamaicabraden » Sat Jun 25, 2011 3:10 pm

have a voltage tester in hand so that you can test. btw, quick question, i have the same issue in our bathroom. we just thought that the bulb had gone but it doesn't actually, the bulbs just don't works in the fitting. can i still fix this?
jamaicabraden
Posts: 1
Joined: Thu Apr 28, 2011 12:46 pm


Display posts from previous
Sort by
Order by


 


  • Related Topics