PIR light wire

[Dave]

What type/rating/size wire should I use to wire 2 500 W and a 150 W outdoor lights plus one extra sensor? Reason I ask, is that I know twin and earth rots in sunlight, but is there anything better than a suitably rated flex? It will be well above hand height.

I am going to our son's house in the morning to correct his lighting problems. Cable to lights comes from the back of a boxed in 13 Amp socket, no fuse and 1.5 mm grey twin and earth. This arrives at the light above his back door and then travels around the corner to what I am guessing was another light. It hangs down, disconnected, with the tails wrapped in selotape. The only good thing, is that the ends are well separated.

Another unrelated problem is in his lounge, where there are 2 switches at opposite ends of the room. The switch near to the front door is a normal single pole double throw. The other one is a dimmer switch. When I took off the dimmer switch front I found that one of the two wires that should be used for a 2 switch situation had been disconnected and wrapped in selotape.

I wonder what else I am going to uncover :-(

Thanks for reading

Dave

[David Hansen]

On Sun, 04 Mar 2007 17:24:45 +0000 someone who may be Dave wrote this:-

A lot of lights.

The answer partly depends on how long the cable runs are to each light and the type/rating of the protective device. Let us know and we may be able to help you further.

What precisely is the extra sensor for?

Are all these lights on the outside walls of the house? If so it is best to wire them from inside with just a little cable outside. Along the outside wall doesn't look nice and also introduces questions of sun, cold and so on.

Either way place a box near the light, I assume linear halogen, then run a short flex from the box to the light. If the fixed wiring is to run outside I suggest twin and earth inside conduit is suitable. Those able to cope properly with other types of cable wouldn't need to ask the questions you have.

[John]

Christ, you are going to correct problems and you don't know how to work out what size cable is required, or which type to use?

I wonder how much an electrician is going to cost him after you have been asking people on here what to do. If you haven't a clue then leave it alone. You might end up blowing yourself or someone else up - for which you could be prosecuted!

[Dave]

Read again my paragraph above and you will see that I am fairly conversant with mains cable. I am merely asking what type of cable (is there a type) is suitable for permanent outside use. I could use 13 amp cable, but there may be a cheaper, lower rated one that I can use instead

I have done a hell of a lot of electrical work and the only thing that I have made a mistake on was wiring my own outside light at the front. I forgot to add a fuse between the ring and the spur. As I am decorating that room right now, it will be fixed before the end of the week.

If you can't offer advice without nasty comments, then keep your thoughts to yourself.

Dave

[David Hansen]

On Sun, 04 Mar 2007 20:06:32 +0000 someone who may be Dave wrote this:-

You are not that conversant with cable though. Cable sizes are measured in square millimeters. What current a particular size of cable will safely carry depends on many factors; ambient temperature, sunlight, how it is installed and the number of cables close together being just some of these factors.

[Dave]

What, 3 lights?

The house is a 1940's built semi and the cable will run from the near neighbour side of the kitchen, along the back until it reaches the gable end, turns the corner and ends up at the front door, which is at the almost opposite corner of the house from where it started.

The one light that is there at the moment is powered straight from the back of a 13 Amp socket with no protective device, into 1.5 mm twin and earth. I propose to take the start of the cable from a suitably rated 13 Amp type plug, until such time as the panelling that prevents me from getting to this socket is removed.

The 150 W light is to be used to illuminate the 5 steps down to the street. Due to the way the garden is right now, the light will have to be quite high up, in order not to annoy the neighbours and the sensor quite a lot lower to catch a body when leaving.

This is designed as a quick fix, but may be up there for a number of years before it gets sorted on a permanent basis. At the moment, it is not possible to get the cables outside the wall without ripping up a lot of flooring (laminate.)

This was part of my original question. Is there a cable that can take full sun and cold and is a similar colour to Accrington brick that I can run round the house?

I don't think that he would go for conduit, just my gut feeling.

I asked the question as I am unfamiliar with flex cables, other than the only one I use for anything heavier than a couple of Amps. I know where and where not to use twin and earth, but I have no data about lesser than 13 amps for flex. I just thought that a smaller cable could do the job and be less visible. The total load will be just over 1150 W. Or 5 Amps. I know my Volts, Amps, Ohms and Mho's.

Many thanks for answering me.

Dave

[Owain]

Hi-Tuff (see TLC website). Available in any colour so long as it's black. Or possibly white.

Owain

[Dave]

Yes, I know about this.

Now you are getting to what I don't know about. Inside a house, I would not have had to ask my original question.

I am an engineer and have never had any formal training as a leccy, but several years lurking on here and my hobbies of electronics and radio construction have all taught me.

When I worked in the aerospace industry, I always told each new starter that there was no such thing as a stupid question. If you are unsure, you should ask and not feel embarrassed.

Regards

Dave

[Andy Burns]

No, 1.1kW of them.

[Dave]

Thanks, I'll try and find some.

Dave

[Dave]

I did think that myself and tried talking him into lower Wattage lights, but he is a police officer and thinks that a bright light will deter anyone from entering his property. The gable end light will be his greatest challenge, as he is more than a floor above his next door neighbour :-(

Dave

[John Rumm]

that you could use T&E inside conduit.

[David Hansen]

On Sun, 04 Mar 2007 20:39:40 +0000 someone who may be Dave wrote this:-

As has been said over 1.1 kW. The cable you select must be able to deal with this in terms of voltage drop, current carrying capacity and short circuit current. How you do this is up to you, but I suggest getting hold of one of the books from a library if you are determined to do it.

[David Hansen]

On Sun, 04 Mar 2007 21:19:30 +0000 someone who may be Dave wrote this:-

Then why did you talk about 13A cable in one of your postings?

I doubt if any of us are mind readers, able to read the mind of your son or yourself and thus know the orientation of the proposed run, shading, distances and the other things necessary to do the calculations. If you are determined to do it then get a book out of the library and read it thoroughly. Then you may understand the possible pitfalls.

I doubt if anyone here has the time or inclination to run through the whole cable selection process on a newsgroup. That is what books are for. I have been doing things with electricity for over 20 years since my first training, but when I need to size cables I nearly always get the books out and do it properly. That also has the advantage that one can often use smaller cables than one might think. However, my guess is that in this case the correct size will be larger then you think.

As it is only temporary do it in conduit, after calculating the right size.

[Jim Alexander]

Normally a spur would come off a ring without a fuse but with appropriately rated cable and the spur would normally be terminated in either an unfused socket outlet or a fused connection unit. In my eyes that's not a forgot its a didn't know.

To get back to your original question and some responses there quite a lot of confusion about what is good wiring practice and what is enough to avoid risk of overload and perhaps fire. Change to a 13A fused plug and you will almost certainly avoid fired risk whatever dodgy cable you use but please don't expect people here to condone dodgy wiring practice which you and your son are inviting by reluctance to consider conduit for example. A bit of pvc conduit for a temprary job is hardly permanent.

Personally I think it's better for OPs who have asked for advice not to criticise.

Jim A

[zikkimalambo]

Following on from what others have said, by all means buy 500W lumineres, but put the lower rated 300W lamps inside.

Mr Plod will not be able to tell the difference.

[ARWadsworth]

Ask him if there are any sorts of lights I can use to stop police officers entering my propery :)

Adam

[meow2222]

T&E is fine wrt uv degradation if it is painted with a coat of oil based gloss topcoat, which chemically bonds to the pvc and blocks UV.

I'd replace the 500ws with 150ws, as there is zero evidence to believe that grossly excessive outdoor lighting puts crooks off. The money thereby saved could then be spent on some security feature of real rather than imaginary value.

NT

[Dave]

Thanks for that, I think he will find this a tad too expensive. I think that I will put up 13 amp cable and urge him to come out from the upstairs under floor as soon as possible, as an earlier poster recommended.

He will not entertain conduit. So it looks like I will have to come to his house with a knife to make him change his mind :-)

Originally, I was under the impression that there was an all weather cable that could be run for this job. Apparently not!

Dave

[Dave]

See my post to John Rumm's post. It looks like a temporary 13 Amp flex until the floors come up in the upstairs rooms. My original worry was that there _might_ be cable that could stand heat and cold tacked onto an outside wall. It looks like there isn't, apart from a very heavy armoured one.

Thanks

Dave