# Forum Home Renovation Lighting  lighting circuit

## baileyboy

Hi all sparkies and electrical engineers, 
I need 4 new fluorescent lights and 1 motion sensor light for my deck. So I had a look at my distribution board today to get familiar before the electrician coming to quote tomorrow. I wasn't sure if he will link the from existing lights in the house or run a new circuit. I turned the light circuit breaker off and all the lights in the house went off. My question is - is this normal for all the lights in a 3 bedroom house on a single circuit? From memory, I thought we're only meant to have 8 100W light bulbs per circuit. Can someone confirm? Is that safe?

----------


## chalkyt

What you have is fairly normal. Most lighting circuits are 1.5 mm sq cable which under worst case conditions (e.g. enclosed in conduit, enclosed in insulation) would be rated at 10A or more. i.e. it can handle 2400W (or 24 x 100w lamps). In an ideal world, you would have two lighting circuits so that in case of a failure, not all lights go off at once... but this doesn't happen very often. Most places have one lighting circuit). 
So, to answer your question, I would expect the electrician to simply connect the sensor and new fluoros to the existing circuit.

----------


## baileyboy

thanks. I guess most people wont have all the lights on at once. But do you think its an overkill if I ask him to put the new lights in a separate circuit? I just assume it will be safer...

----------


## chrisp

If you are keen, you could ask the electrician to break/split the existing light circuit in to two.  As long as they can reach the cabling about halfway along the light circuit, they and run the new circuit in at the break.  It'll probably cost a bit more, but if you are going to the trouble of getting another circuit installed, you might as well get the extra benefit of having about half the lights on each circuit.

----------


## Duff5000

I dont recall a single time i have had the lights go off without the rest of the house going off as well. Personally i wouldn't bother with the extra circuit (well unless the price is pretty much the same). 
I was adding up my max lighting power usage recently and with all the low power lighting choices now it wasnt much at all. From memory if every light in the house was on i would only be using about 2A.

----------


## aussieslr

I'm an industrial sparky and I've seen all sorts of problems with fluro lights. They have tombstones, ballasts and starters which can fail plus the heat generated during operation can burn the wiring. Adding a circuit and putting the fluros on it would isolate them and make fault finding easier in the future. My advise would be to get the sparky to quote both ways and if it isn't that much more go for a second circuit.

----------


## baileyboy

Thanks guys. I'll talk to the electrician when he comes in on Friday.  
Anyway, I replaced my noisy 4 foot fluoro in the lounge with one of those spot light fluoro type and it worked well for two days and now one of the bulbs is blown. I checked the wiring, measured the insulation to earth etc, and all ok. Maybe its the heat... 
We quite like the style so thinking of replacing the fluro in the kitchen with a similar one. My problem is that the kitchen ceiling is made of fibro. Not sure if its asbestos but quite likely. I'm considering gluing a piece of 15x15cm piece of wood to the ceiling and attach the light to the piece of wood. The reason for 15cm x 15cm is to increase the surface area to create a stronger bond. Went to Bunnings and the girl suggested Sika Contact Adhesive.  
I would love your opinion on this.

----------

