Lighting Circuit Overloaded?

[MikeJM]

I intend to put lights on the outside of my bungalow but on toting up the lights/wattage on the existing light circuit in theory I could be pulling 2400watts (11 amps?) if all the lights were on at the same time, (although I can`t envisage any scenario where this is likely to happen, only me and my other half live here).
From info gleaned from other postings and the "how to" section I think this is a problem and I should not run the new outside lights from this circuit. If so how much of a problem is it and how am I best to get round it and what is the best method for running the new lights?
On my CU there is a spare unused switch that has been switched off since we moved in two years ago. If the circuit is overloaded could I use this to spread the load and how ?
Can I run a spur of the ring main throuh an FCU for the new outside lights or what would you advise? The new lights are security type and will be 4 lights x 150watts.
Grateful for advice please.

 

[sm1thson]

118mm Linear Halogen Retro fit 24W Halogen replacement lamps
(I expect to be as bright as 150w normal, 200w if your lucky)
http://www.toolstation.com/shop/Lig...nergy+Lamp+500w+to+24w+24W/d220/sd3074/p16867 -also available on ebay and many other places. -has anyone had a good try of these yet?

 

[Pensdown]

I was to lazy to type last night but I'll try and help if I can

Based on you existing load of 1800watts, before applying diversity (not all lights on at once) the design current is 7.82amps which is greater than a normal domestic 6amp fuse/MCB.

1800watts of lighting in a bungalow seems a bit high - are you sure you've added them up correctly?

What size is the existing lighting fuse/MCB?

 

[MikeJM]

Hi Pensdown
Thanks for the reply. Checked my figures and I have 2370 watts . Its a four bed bungalow with wall lights in some rooms, large kitchen and bathroom with recessed down lights plus integral garage that has lights.
MCB is 6 amp.
Any advice?
Thanks
Mike

 

[fattony]

is all the lighting on 1 circuit? as someone mentioned above after applying diversty the figure drops to 7.82Amp so it could be a posability of replacing the 6 Amp MCB with a 10Amp.

Does see odd to have the 4 bed bungalow and garage on one circuit though

 

[MikeJM]

The CU has two 6 amp switches and one has been in the off position since we moved in two years ago. There are only two 1.5mm cables going out of the CU for the lights. The other cables are 2.5mm or larger for cooker etc.
From my limited knowledge I agree it seems odd but we live in Cornwall and before we moved here from "up country" as the locals say we viewed many a property that had unusual or quirky building methods used either by design or from mods over the years.
It seem that down here they were somewhat on their own and did a lot of things (some still do) different.

 

[fattony]

As its a bungalow have you considered having the lights wired back to the consumer unit, I believe (someone will shoot me down if wrong) any electrical work outside comes under part p.

 

[Pensdown]

I know this is not what you want to hear but personally I would suggest you get a sparks in for the following reasons.

• You can’t add any more lights to your existing circuit as it is already overloaded
• You will need to install a new circuit for the outside lights. To do it properly and protect your investment you will need to notify Building Control and pay their fee. Look for Part P in the wiki section.
• Their fee will around the same as a sparks will charge to fit four outside lights on a bungalow.
• I would ask the spark to have a look at your existing lighting with a view to splitting it across two circuits to reduce the load. The outside lights would form part of one of these circuits. After some testing and calculations the sparks may also be able to increase the MCB ratings to 10amps if required.
• Also, single lighting circuits are not a good idea because under fault conditions you have no lighting at all.

Please ensure your sparks is listed here

http://www.competentperson.co.uk/search.asp

Edit

The CU has two 6 amp switches and one has been in the off position since we moved in two years ago

Another reason to get a sparks in because there probably was two circuits but for some reason one has been disconnected.

 

[fattony]

the answer no one wans to hear when they realise it will cost money but its the sensible one, new circuit is my vote

 

[MikeJM]

Thanks for the info folks.

 

[holmslaw]

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