Cable size for downlights

[macadonald]

Hi Guys,

Have I caused myself or the electrician any problems by running 1.5mm twin & earth between downlight locations. I suddenly thought this may be too large a cable (if using a transformer).

I thought that's what the electrician told me to do very early on in my renovations. He is a mate and will be coming to wire everything up in the future, but just wanted to check as they won't all be easily accessibly to change the cable.

Thanks

 

[ricicle]

Here's an idea - why don't you ring and speak to him

 

[macadonald]

Because he's away and it's bugging me.

I thought someone answering in the electrics forum would know the answer to a question like that...

 

[ban-all-sheds]

Here's an idea - why don't you ring and speak to him

Because the OP has one of those electricians who is never around to ask, but is always going to turn up, connect stuff the he has installed, and "sign it off".

http://www.diynot.com/forums/viewtopic.php?t=257231&start=0

http://www.diynot.com/forums/viewtopic.php?t=265196&start=0

http://www.diynot.com/forums/viewtopic.php?t=271634&start=0

http://www.diynot.com/forums/viewtopic.php?t=274449&start=0

 

[ban-all-sheds]

I thought someone answering in the electrics forum would know the answer to a question like that...

We do.

We also know that if you want an electrician to sign documents to say that he did the design and installation of something, and that it complies with the Wiring Regulations and Building Regulations it is the done thing to actually let him do the design and installation.

And we also have a pretty good idea about the existence of this electrician too.

 

[phatboy]

1.5mm should be ok, a bit more of a fiddle, but still do-able.

 

[macadonald]

Thanks Phat-boy, that's a nice straight forward answer that I was hoping for from a DIY formum.

Not like ban-all-sheds who seems to be on a war path. For some very strange reason and I can only think he has a lot of time on his hands, he is searching through other threads of mine 5 months old and making rather pointless 2 cents worth...

Just a thought ban-all-sheds, people in DIY use this forum for HELPFUL advice. Don't put them off with pointless and nasty responses. It was a simple question askign for a simple answer. You just commented on one of my 5 month old posts and hadn't even read it properly.

 

[ban-all-sheds]

Thanks Phat-boy, that's a nice straight forward answer that I was hoping for from a DIY formum.

Yes - DIY.

I take it you know what that stands for?

You are making claims about the involvement of an electrician, and yet here you are asking questions about work which you are claiming you are not doing yourself, i.e. designing and installing electrical circuits.

If you want to DIY then fine - DIY, and take responsibility for the whole thing, end to end.

But if you are expecting somebody to sign official documents which certify that he did the design then he has to do it and he is the only person you should be asking when you have design questions.

Just why do you find that so hard to understand?

 

[macadonald]

Who are you to tell me what DIY encompasses. If I am renovating my house and an electrician comes in and says that in order to save money (DIY), I can run the cables and he will come back to connect them, then so be it.

If you want to be so padantic then the DIY aspect of this is the cables and the professional input is the connections and signing off for which I won't ask questions on this forum. The electrician is happy with that and I know that I need him to do this in order for him to sign it off and meet regulations.

A suggestion, if you don't want to respond to a thread or don't have any advice relating to the question - then Don't! All you have done is been the one person who has tried to be dificult.

I have used this forum throughout my renovation and have had endless very helpful and informative responses. It's a great place, but lets keep the responses positive rather than slagging me off and claimign there is a non existent electrician.

 

[ericmark]

I do feel BAS is a bit too quick off the mark but what he says is correct.

So here is the problem. Low voltage (230v) at 5/6A as used for lighting supplies can be transmitted in near every size of cable permitted from the minimum 1mm sq permitted upwards but as one exceeds 1.5mm sq getting it into terminals may present a problem.

However extra low voltage (Under 50v normally 12v) has much higher current and although one is permitted 0.75mm sq the volt drop and current limitations mean in real terms one can find rather thick cable is required a house wired in the Falklands by me used 6mm sq cable with a 24v supply for lighting.

Clearly using small LED lamps is very different from using tungsten lamps and also daisy chaining the lamps will be very different from individual supplies. With the small quartz tungsten lamps powered from an inverter the whole idea is to correct any voltage variations by using an inverter so it would rather defeat the whole idea if the cable was too long or thin and the volt drop would mean reduced light and live from the lamps used.

It is very easy to jump to conclusions as to what some one is intending to do and to give a totally wrong answer. Clearly from what I have said one should keep the inverter (you call it a transformer but it's a bit more involved than a simple transformer) as close to the lamp as possible so all cables will be for the 230v supply. However in the past I have seem a 100VA inverter at one end of a room with 10 x 10W lamps around the room which looked like a planetarium to me with the lights being far too small for the room and the volt drop making the end lamps have a reddish look to them.

To me although phatboy's reply may seem better he could very easy have got you using 1.5mm sq cable for a 10 meter run with ELV which would be far too much of a volt drop. So in real terms BAS and ricicle were giving a better reply.

It takes some time to write out a reply like this and still it does not seem to sink in that design is an important part. The paperwork is available for three signatures one for design, one for installation, and one for testing and that is because on larger jobs they are often three different people.

Installation is the easy bit. You follow a plan and do as you are told and other than for the Part P charges when not all done by same person I see no reason why a DIY guy should not do the donkey work.

Design however has to consider many aspects and the testing uses equipment so expensive that even if the DIY guy could work out how to use it likely it would still be cheaper to get some one in to do it.

What I should do I suppose is to store this reply and then copy and paste when the question is asked again. There is a section where people have spent time detailing all I have said but it seems people would rather start a new post than read the help section.

 

[macadonald]

Thanks EricMark,

That is a very useful response and it is worth saving. I will read it a few times to make sure I understand it properly. But what you've highlighted is that I need to go back to the electrician and confirm everything I've done too date is okay (obvious perhaps). I was possibly a little relaxed about the whole thing.

As you said, BAS is a little quick to answer without thinking. No doubt he may often be right with his answers, but unless he responds in words that make you want to pay attention it just annoys people. TBH I just did a search on user name and it turns out he is a member on loads of these types of forums and annoys lots of people, but each for himself.

Thanks once again for your response.

 

[ban-all-sheds]

But what you've highlighted is that I need to go back to the electrician and confirm everything I've done too date is okay (obvious perhaps). I was possibly a little relaxed about the whole thing.

Here's an idea - why don't you ring and speak to him

We also know that if you want an electrician to sign documents to say that he did the design and installation of something, and that it complies with the Wiring Regulations and Building Regulations it is the done thing to actually let him do the design and installation.

if you are expecting somebody to sign official documents which certify that he did the design then he has to do it and he is the only person you should be asking when you have design questions.