Can anyone tell me why some lighting circuits use 1mm cable and some use 1.5mm. What is the maximum number of battenholders can you have connected using either 1mm cable or 1.5mm??
Rule of thumb is 10 per circuit I usually use 1.0mm for a domestic installation gives more space in the switch boxes,many use 1.5mm though. It depends on other factors but in a domestic installation I have never found an instance where I had to use 1.5mm instead of 1.0mm
Yes LD is right. allow about 1100w load per lighting radial, and with each light taken to be 100w, that's 10 -11 units. Always use 1.5mm meself, as it's got abit more meat. Triplock
I've got a 500w floodling on one 6A MCB, so I'm guessing I shouldn't put any more than 5 Battenholders on the same radial? On the other 6A MCB, I know that each battenholder won't consume 100w though as I have all energy saving bulbs - don't suppose it would meet regs if I put any more than 10 battenholders on my other circuit though!
Hi Deano All circuits should really be designed to satisfy Regs. Its all very well using "rule-of-thumb" but I think this isn't good advice and should not be used for lighting circuits. The 100W per light fitting is a design minimum to enable initial cable sizes to be obtained. You count up the number of fittings, multiply by 100W then divide by 230V to get the current in amps. This will give initial cable size. Then you have to look at length of cable route and other factors that will determine actual cable size. In domestic situations there are few light fittings so 1.0mm2 is usually ample. However, 1.5mm2 is used where loads are greater and cable runs are longer. Also if light fittings are chandaliers all the load could be taken up by as little as one, two or three fittings then you have to start increasing cable size and dividing up circuits. UP
No,, because at a future date, someone could fit 100w bulbs You can only design for today, who's to say the next owner doesnt put in 50+ halogen lights in place of your single 100 pendants? After all it will have be wired correct with 1.0mm cable. Look at what you need work out the current with diversity factors then install whats required not might happen. Next owner might go for 1000W halogenss in every room, now thats loading it up a bit
I usually wire the loop-in/out in 1.5mm and the switch cable in 1.0mm it helps in identification later on.
I usually wire the loop-in/out in 1.5mm and the switch cable in 1.0mm it helps in identification later on. Ahhhhhhhhh....., Now thats opened up a kettle of worms (what ever that means ?). Although you see a mix of 1mm and 1.5 quite often it is wrong to design and install like that as you are downsizing the cable at the switch drops. Also the two way switching is probably the longest run on the lighting circuit (when you add the length of the strappers and common)so there is no point in wiring in 1.5 (although i see where your coming from, loading etc)
I usually wire the loop-in/out in 1.5mm and the switch cable in 1.0mm it helps in identification later on. That's innovative
I tend to stick to 1.5mm. It can be a bit of a squeeze in some instances. I once fitted 2.5mm to a bathroom light, as I had no 1.0 or 1.5. As I'm not Part P registered I had to get this approved by a BCO who said "Better that way around". He was OK with that provided I could secure the conductors etc into the connectors, and secure the cable grip on the fitting. CC