Increase Lighting MCB from 5 to 10amps?

[MrFrisbee]

I have just had some building work done and a few more lights installed.

This means that my 5 amp lighting circuit is drawing about 4.9amps and blows sometimes when all lights are on.

There are only 2 rings into the fuse and no room to move one to another fuse (not easily).

Simple solution would be to increase the fuse from 5 to 10 amps (There is no 6amp in the Wylex NB range). Can the wires handle this or is it a bad idea to do?

Thanks,

Charles.

 

[PrenticeBoyofDerry]

Depends on the size of your cable (csa) that is supplying the lights and whether it routed within thermal insulation at at any point.

 

[rebuke]

It depends on what size cable is installed, and what switches and light fittings you have, they may or may not be rated to take 10A. Also, note that this work would be notifiable to your LABC under Part P of the building regs, as it involves changing the protective device...

 

[ericmark]

Most ceiling roses are rated 5/6 amp and so this limits the protective device size if you are using fluorescent lighting then it is common to have fuses inside each fitting and you are permitted a 16 amp supply but it is unlikely this will apply to any house.

Although with new installations because of the buried to 50mm rule most lighting circuits are RCD protected before 2008 this was rare and the earth fault loop impedance will be an important factor for safety both for electric shock and fire protection and you will need to measure this first.

Because the meters cost around £250 it is unlikely it would be economic to DIY especially when including the LABC charges of over £100.

I would suggest the most economic method would be to change all the easy up upgradable lamps to energy saving.

I do wonder how you can draw so much current at 60W per bulb i.e. 0.26 amp you need 23 lamps to reach 6 amp that should be ample for any house.

If I consider my house
Living room 10 x 7w CFL = 70W with 40W tungsten 400W
Dinning room 6 x 7w CFL = 42W with 40W tungsten 240W
Kitchen 4 x 60 fluorescent tubes = 240W
Hall 1 x 40W
Garage 2 x 60 fluorescent tubes = 120W + Emergency lamp
Landing 1 x 20 fluorescent tubes = 20W (Battery backed)
Bedroom 1 x 22W CFL + 2 x 11W CFL = 44W with tungsten could be 160W
About same for other 2
Bath room 4 x 50W tungsten lamps helps heat the room.
Total for house with CFL = 3.75A even with 4 x 50W spots in bathroom if I swapped all CFL for tungsten jumps to 7.56A but other than a bulb blowing and going short circuit when it blows I have never had the MCB trip so I think you are doing some thing silly some where!

 

[sparkyspike]

The 5A circuit will have been designed as such, so don't be tempted to alter the fuse rating. Much better to split the two lighting circuits over two fuses.

Also, I agree with ericmark that there may be more to this than just a small overload. What do you mean by a 'few more lights'? Who did this work and why aren't they putting it right? I'm assuming it wasn't an electrician.

 

[JohnD]

4.9 amps will not trip a 5A breaker

What lamps have you got on? Halogen floodlights? Chandeliers? Cannabis growing lamps?

When you answer I will suggest how the use of CFLs will last longer and save you money

 

[MrFrisbee]

Seems the best option is to move one of the two rings that makes up the lighting to the second consumer box onto a 6 amp fuse (with RCD).

The property is old and the wiring done perhaps 20 years ago with some upgrades.

Thanks.

Mr. Frisbee.

 

[MrFrisbee]

FYI I am using a mixture of incandescents, halogens (low voltage) and a couple of mains halogens. There are quite a lot of bulbs and I will probably lower the wattage of some of the fittings anyway as there is too much light now with the new lighting arrangements anyway.

 

[JohnD]

quite a lot

is that more than 20?

why aren't you using energy saving lamps (CFLs)?

 

[sparkyspike]

If your lighting circuit really is a ring, then be sure to seperate the two circuits completely if you are going to put them in their own breakers.

 

[ban-all-sheds]

I have just had some building work done and a few more lights installed.

Did you not get an electrical certificate as part of this?

What sort of building work was it, and where were the lights added? If they were notifiable have you got a Building Regulations completion certificate?