sheath colour?

[HappyHippyDad]

Hi,
I wondered if anyone could tell me if there is any legal requirement or safety requirement for using certain coloured sheathing for a 4mm 3core indoor cable?

Its going to be used to supply power to my shed (just the indoor bit).


I've found this on e-bay and wondered if it is ok?

Lapp Olflex classic 100 3 core 4mm2 cable 20m

Also, does it have to be flattened sheathing or is this circular sheathing ok? It will be going straight into the consumer unit.

Thanks, Steve.

 

[gibbyisking]

hi mate what are you going to be doing? is your shed connected to your house?

 

[Knobhead]

That’s flex!
From FleeBay!
Don’t touch it with a barge pole!
Probably manufactured by the Ying Yong Corporation of Outer Mongolia!
If you enlarge the photo it even has “FLEX” printed on it!

 

[Richard Burns]

The sheath in this case is the grey outer plastic and as far as I know there is no requirement for this to be a specific colour, the insulation of the cores should be as they are in the flex above (brown L, Blue N, Green/yellow E).

I would not recommend using this flex for your internal wiring in the shed, as Tony says above.
From a reputable electrical wholesaler buy some regular twin and earth cable of the appropriate cross sectional area to be able to supply the required current for the application.
If you are unsure of the correct cable then someone else should be on site to advise you of the correct requirements.

 

[Inteificio]

What you are doing has the potential to cause a fire. You can bodge quite a few things on electrics, do not cheap out on the wire.

Use a bs7671 cable calculator to work out the rating, 63A cable does not mean it can take 63A in a wall.
Also you may interfere with tripping time.

Make sure the cable and breaker are the correct type or there is a good chance of it failing.

 

[SPARTYKUS]

As above. At first may seem like a jolly good telling off, until you've seen a house burnt out by electrical bodgings.

My best mate got me round as he had a loud bang & burning smell on landing (& no power up stairs) - turns out the 2.5 radial was supplying the up sockets (on a 15A 3036, possibly) . And the immersion. Oh! And a 10kW shower.

Boom shak a lak.

Looked like a grenade had gone off under his nice fitted wood floor we had to rip up.....

 

[Lighthouse Phil]

The cable in the photo is NYM-J, its a very common cable in Europe. Its used a here in Ireland. As long as its got the required Standards stamped / printed into it, it will be ok. But I think you would be much better off going to your local sparks / wholesaler, as you'll never know the history of that cable off fleebay.
http://lapplimited.lappgroup.com/index.php?id=735223&no_cache=1&rel=3236d673&pageID=758802

 

[Lighthouse Phil]

Also see this

NYM-O, NYM-J - lapplimited.lappgroup.com

 

[HappyHippyDad]

Thankyou all,

I will not be buying this cable!

(Gibbyisking) - The shed has already been wired up by the electrician and now it needs connecting to the house. At present there is just a 4mm cable plugged in to a socket in the house which leads to a 2 way consumer unit in the shed feeding 3 lights and 3 double sockets.

I can hear all the gasps and even I know this is very unsafe so I only use one light and one socket at a time until the cableing to the house has been completed properly. i.e it will have its own seperate circuit running from the consumer unit in the house.

As a point of interest, just how dangerous would it be to wire the shed into the back of a socket on the ring main (one that has no other spurs on it)? I realise this is now no longer legal but from a common sense point of view is it safe? In reality the maximum I will have on at any one time in the shed is 3 60w lights a radio and a table saw. Would this really be so bad (around a 100w approx)? I know quite a few people that have done this and they just use common sense about not using too much power.

Thanks all, Steve

 

[Marvo]

I realise this is now no longer legal but from a common sense point of view is it safe?

I think the problem with your question is that as qualified electricians and engineers most people on the forum are legally bound by the regulations and won't sanction installing electrics in any way other than compliant.

As a lay person you can do things differently and if it ever comes to a court case there won't be the intent to have harmed someone so you'll relatively get away with it. Don't get me wrong, this won't bring back the dead or heal the injured but it will give you the luxury of some plausible deniability that a professional won't have.

 

[Richard Burns]

The current system you have sounds very dangerous and you should not be using it at all. 4mm cable will not fit into a standard plug so there must have been some modifications made here, which will make it worse.

Please contact the electrician who wired the shed and arrange for a safe, designed and tested installation to be put in place as soon as possible.

Table saws can take a high inrush current and may cause unwanted tripping.

 

[HappyHippyDad]

Thankyou both to the moderator and to Richard Burns.

I assumed the 'make do' cable going from a plug socket in the house to the shed to supply power was a 4mm, there are no alterations to the plug and it fits fine so I am assuming it must be 2.5mm.

If it is potentially that dangerous to use the radio/light/table saw then until the proper cables are added I will stick to just the light and nothing else. If I get a reply back that even that is dangerous I will simply stop using everything and wait till it is finished properly, but surely that is a tad over the top.. its one 60watt light!

Again I do respect the comments made by the moderator regarding the law but i find it frustrating that that restricts or even precludes discussion. I would love to understand more about spurs, not what the judicial law says (of course this has to be respected) but what the laws of physics say.

I think the maximum load that can be taken by a socket is 3000watts and the ring main is about 7000watts. This is what the law says but that doesn't help me understand it any better. With regards to physics what wattage could the ring main take without the cables heating too much and catching fire and more importantly how do you determine this figure (what natural laws are involved). Obviously not because I will do this, that would be madness, but I want to understand rather than just be told a figure!

I've got a little carried away there, sorry. But I think it is only through clear, open discussion without fear that you can truly learn and in return truly understand something and therefore be safe.

Again, I will not do anything that is dangerous and already I have hugely restricted the power usage in the shed thanks to advice from the forum so far.

Thanks again, Steve

 

[Richard Burns]

Standard 13A plugs are designed to take a 1.5mm flex at maximum, this has a current carrying capacity of 15A in ideal situations and this level cannot be exceeded because of the 13A fuse in the plug.

In supplying power to a location there are a large number of factors to take into consideration to ensure a safe installation.
The potential current demand of the location, the level of protection required, the current carrying capacity of the cables used, the installation method, grouping, ambient temperature, requirements of the regulations for the location, to name but a few.

Using a spur off a ring final circuit then introduces the considerations of what other power may be used on the existing ring compared to the protective device as well as the current demand for the spur and the requirements for keeping the loading on the ring as even as practicable.

A normal ring final circuit has the potential to be used to its capacity very easily as you can tell from a ring with 10 double sockets this could, at maximum, use 130A if every socket is used to capacity which is way above the 32A protection supplied normally, in a normal domestic situation this does not occur. however with a separate supply attached to the ring a different level of usage come into play and the ring could easily be overloaded, with the potential for fire at the worst and nuisance tripping of the power at the least.

What you are describing with a small consumer unit in your outside building means that the house ring protective device is probably the only one actually protecting the circuit and this can lead to overloading of the cable especially if the cable is not sufficiently rated for the current demand.
The consumer unit being connected with flex is a non standard method and the connection are not designed to accept this cable and may cause problems with secure connection into the consumer unit leading to junctions heating and potentially fire.

I hope this goes some way to explain the problems that may occur in a badly installed arrangement and the reasons why we are not sanguine about providing any form of advice on the use of an untested and incorrectly installed arrangement.

 

[Marvo]

Again I do respect the comments made by the moderator regarding the law but i find it frustrating that that restricts or even precludes discussion.

My comments weren't as a forum moderator they were just personal thoughts. In your previous post you stated that the new CU in your shed was supplied by a 4mm cable that was plugged into a socket. You followed later by inquiring about making it a permanent spur from the socket.

I was just worried about the direction it was heading.

It would help if you could answer a few questions;

Does the new shed CU contain RCD protection?
Does your house CU have RCD protection?
What type of earthing arrangement is there?

If you can attach a photo of the CU in the house and one of the CU in the shed it would be even better.