Electrical question (again)

Am I right in thinking that outside LED floodlights can be connected together in a daisy chain so that it goes power source - light - light - light - light ? I'm pretty sure you can, and that I have in the past, but I thought I'd check.

Also if that's the case then how many 10w LED lights could be daisy chained together and powered by a standard 13amp plug?

Would 5 X 10w led floodlights over a distance of 50metres be fine with 2.5m twin and earth on a 13amp fused RCD plug be ok or am I talking absolute rubbish as usual?

 

Current equals power/voltage.
So if you've 13A you can have roughly 3kW or 3000W of lights on a plug.

 

Most lights will struggle to fit a 2.5mm T/E cable in them though. Especially in and out.
You can use 1.5mm cable from a 13A fuse.

 

No, absolutely not in series!!! Assuming each individual unit is designed to work from 240V AC mains, then you need to wire them all in parallel across live and neutral. If they are all 10W units, then you can connect 312 units in parallel and still run them from a 13A plug.

I assume you're working on a new floodlight system for BFC.....

 

Most led floodlights on the market. Are throwaway and cable fitted. Run a supply and fit a junction box where the light is situated. run supply from each junction box to the next light. . Repeat as often as you like. At 10w. Theres no way you'd reach 13amp. unless your doing the whole street and some.

 

Thanks to all three of you. Would a 1.5mm twin and earth cable do the job then with 5 lights over that distance?

If a 13amp fuse is over the top then is it better to fit a 5amp or doesn't it work like that?

And the parallel/series thing (and what hooky fella said), I'm a bit thick obviously and I think I said the wrong one. What I was thinking was a long 50m cable. Plug on one end and then every 10 metres a junction box with a prewired 30cm cable down to the light a bit like the absolutely terrible image below.




I'm not as bad at electrics as i appear. Honest. I don't undertake anything without getting advice first and can do the physical work quite well.

 

1.5mm cable will be fine. I'd fit a 5A fuse if you have one as it will reduce the chance of tripping the circuit breaker if there is a fault. It'll take the lighting fuse out and you'll know where the problem is.

 

As Stahlrost says, wiring in series causes a reduction in voltage across each unit. There may be a fair bit of voltage tolerance with an LED bulb so you might get away with a few in series without enough voltage drop to stop them working properly. Probably best to follow his advice and wire them in parallel though.

Edit; probably better to not have exterior lighting at all to avoid increasing your carbon footprint and also not contributing to light pollution....

 

I THINK that parallel is what I was actually thinking of rather than actually in and out of each light.

 

5 lamps is 50W (5 x 10W) which is just 0.2A at 240V, so a 3A fuse should be used. 1.5mm cable is fine.

 

I understand what you mean now, you actually used the term "daisy chain" which is somewhat ambiguous. Parallel is what you need, series is right out!!!!

 

Thankyou very much everyone. Now I just need to try not to fall off a ladder

 

Couldn't have drawn it better. Tbh a 1 amp fuse would suffice. So anything really. Would probably put owt I'd got up to 5 amp.

 

Series was the word I was thinking of but was definitely the wrong word

 

Just another word of warning. LED lamps have a huge in-rush (turn-on) current which lasts for several milliseconds. This current can be as much as 100 times the steady state current, so for your setup the start-up current could be 20A for a short time. This is ok for a normal light switch, but if you're using anything with a relay in it (e.g. a time switch or motion sensor) you need to check the spec very carefully. If you don't, the in-rush current will weld the relay contacts and the lights will stay on for ever. You should use at the very least a 10A rated switch in your application, and you can also use a device called a NTC thermistor to limit the in-rush current.

https://lamphq.com/led-inrush-current/

 

You just love confusing me don't you. I was going to use a dusk till dawn sensor or a timer on the socket but now I have absolutely no idea whether that's wise or not

 

If i remember correctly, when I did an electrical course(part p), twin and earth shouldn't be used externally as it is not uv stable.

 

I have done exactly that at home, using a Raspberry Pi and relay to control our outside lights, using a web function to get the sunset time. I had to use a very much overrated relay to get it to work. You need to go for the most highly rated unit you can find, 10A at least, and/or use one NTC per lamp unit. I've got a bagful at home, but sadly I'm in Germany until early December.

 

I've found this on eBay. Reckons its 20amp

https://www.ebay.co.uk/itm/162254321500

 

Hey up as tha bin talkin to a Sparky ?