Old re-wireable fuse board change

[bonn1ett]

Hi everyone,

I am fairly new in the trade and wondered if anyone can throw some advice my way. I recently went to a fairly old property as all the lights had gone off due to a lamp blowing in one of the light fittings which in turn blew the 5amp fuse wire in the board. Apparently this had happened a few times with the lamp blowing/popping out of its fitting?

There is one lighting circuit and hence one 5amp fuse for the whole house - upstairs and downstairs. I recommended to the customer (elderly lady) that the fuse board needs updating and that two circuits are needed for the lighting - upstairs & downstairs. The customer is happy to have a new consumer unit put in but does not want any re-wiring done - obviously if there is any faults found on the existing wiring then i will recommend strongly that the work be carried out.

My question is this, with regards to only having the one lighting circuit, could i perhaps use a 10amp breaker as opposed to a 6amp to cover the whole house - as long as the cable rating is higher than this (not sure if its 1mm or 1.5mm being used, need futher investigation).

any advice would be great

 

[roukel01]

Have you had a look in the old fuseboard to see if the lighting circuits are 'doubled up' onto one fuse? that very often happens. If so, when you come to change the board, splittling the circuits should be fairly easy.

Another thing to think about is the position of the board, is it easy to get to? remember a new dual RCD board (or RCBO's) can trip fairly often, it can sometimes be much harder for elderly people if access isn;t easy.

 

[bonn1ett]

i will check in the board if it has been doubled up, thanks for that.
The board is under the stairs but is open (no cupboard) and easy to get to.
If there is only one circuit (worse case scenario) then could i use a 10amp breaker? Thinking of using RCBO's as its only a 4way board.
thanks for the quick response!

 

[Deleted member 9648]

6a type C's dont usually trip with lamp failure...subject to satisfactory max Zs it's always a good idea to fit type C's to lighting where random tripping could cause a hazard,such as elderly occupants etc.It's normally the type rather than the rating which causes blowing lamps to trip the mcb...I doubt a 10a type B will be much better than a 6a Type B in that respect...a type C will definately help.

 

[Deleted member 19807]

just upping to a 10 amp may not be enough, a type c or d might be needed as long as your r1r2 is ok or get her to change to low energy lamps.

 

[trev]

No matter what you do here I reckon this could turn into a nightmare for you mate. It'll either be riddled with little faults that'll trip your shiny new RCBOs or every time a lamp blows your phone is going to ring. Nothing to stop you using a 10A but is there any justification in doing it? What is the largest possible load?

 

[bonn1ett]

oh right, yeah thats a possibility will look into it thanks. I think my concern is if i only put in a 6amp breaker which feeds the whole lighting in the house, could it trip out or have a tendency to trip out as the load could be too much?

 

[Deleted member 19807]

load too much?

if its not taking out a 5a fuse it won't overload a 6A mcb.

 

[Kiers1970]

is there a Guidance note for installations for the elderly?... Strewth.

 

[Deleted member 9648]

oh right, yeah thats a possibility will look into it thanks. I think my concern is if i only put in a 6amp breaker which feeds the whole lighting in the house, could it trip out or have a tendency to trip out as the load could be too much?

How much lighting load is there?...that'll tell you whether you are safe to stick to one circuit or need to split into two...work out the total load in watts and divide by 230.....as previously stated,type C's will minimise the possibility of lamp failure surges tripping the circuit.

 

[bonn1ett]

the load going on every fitting being 100w works out about 4.5 amps so a 6amp would probably be ok for the whole property but getting a type c rcbo as mentioned may be the way to go.

 

[stuart569]

How big is the house? It would have to be pulling about at least 1.35kw to trip a 6 amp mcb.Thats just under 30 50w lamps lol

 

[Goody]

Apparently this had happened a few times with the lamp blowing/popping out of its fitting?

Check the offendig lamp holder and replace it if needed and try an energy saving lamp. Good luck!

 

[bonn1ett]

it has taken out the 5amp fuse when the lamp blew. The load, going on each fitting being 100w works out approx 4.5 amps, so on paper a 6amp breaker will be adequate, just a bit worrying that a blown lamp= a blown fuse, as mentioned there could be problems elswhere maybe?

 

[roukel01]

a blown lamp very often takes out a fuse. Even more so with an MCB, hence the reason people are advising a type C breaker.

 

[tuckermot]

Hi
if you look at it this way if you have 20 x 60watt lamps all running at the same time that eguals 1200 watts which = 5.21 amps which is under the rating of the 6amp fuse at present apply diversity and its very unlikely the the little oldlady is going to light up her home like blackpool iluminations so i would go for a 6amp type c mcb which allows for ahigher start up current ect which should stop the tripping !

 

[Deleted member 19807]

The fuse blows because of the current draw of the arc inside the lamp as it blows. tell her to fit energy saving lamps.

I have been told that good quality lamps have an internal fuse that stops the trip from going but i have never seen them.

 

[bonn1ett]

thats brilliant, thanks for all your help guys, got a better idea of what to do now.

cheers

 

[Octopus]

How many lights has she got????

 

[bonn1ett]

i didnt go round checking all the lighting at the time as it was getting late...and dark!
she has a lounge with 2 light fittings, kitchen, hallway, landing, bathroom and three bedrooms so doing on this approx 9 - 10 fittings.