Spur security light

[wtf69]

Ha Ha Ha
well from reading the current rated capacity listed in the wiki a 2.5 cable is rated at 20A
so, how can it possibly support 26A which is what effectively 2 x 13A plugs could supply. and yes I am aware that a double socket is probably only rated for approx 18A and it is a miss-conception that it can withstand 26A as to what it could be supplied.

As for my 1.5 cable, I still want soemone to tell me how the set up is electrically wrong. Is it possible that the bulb in the security light could somehow blow up but still create a correct gap for an arc to jump across and the demand jump up to more than 15 A, and even then be higher to create a temperature high enough to melt the cable and set it on fire?

 

[chapeau]

well from reading the current rated capacity listed in the wiki a 2.5 cable is rated at 20A

Well all that demonstrates is that you shouldn't believe everything you read on the internet.

 

[wtf69]

Ha Ha, Your quite right there .

So, do you fancy sticking your neck on the line and saying that it is all right, no sorry, i will re-phrase that..... saying that it does not pose any risk or damage to the property.

I think we all know it is wrong, it just appears that none of the sparks on here will state it!

Oooh I got one, if a spark was doing a report on this item would they put it as a code 1?

 

[chapeau]

... no sorry, i will re-phrase that.....

Let me re-phrase it for you.

Reasonable provision shall be made in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury

Now if your solution satisfies the above then it is OK.

 

[wtf69]

Woah!
its not my solution, as originally stated I have just bought a house and this is all ready installed. When i come across things like this it makes me think what was the original installer thinking off and how unsafe it actually is lol.

Still....

Reasonable provision shall be made in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury

I think the set up covers all those posts.

And as stated I dont agree with it, but do not think it poses a fire / electrical risk either.

And that is what my original question was getting at.... I think lol.

I still have no bites agreeing with me though lol so maybe im wrong!

Thanks anyhow!!!

 

[rebuke]

To answer your question about a situation where the RCD wouldn't trip - imagine a bug of some sort manages to crawl in and then bridge live and neutral in your light fitting - as it's a L-N fault, the RCD won't trip, since that only trips on a L-N imbalance. If the resistance of the bug is appropriate, it could quite easily draw over the fault current that the cable is rated to, without tripping the MCB...

 

[wtf69]

Marvelous, cant argue with that one!
damn those little interfering bugs!!! I need Grissom to come and tell me now what type of bug could create a problem like this without frying and the resistance not breaking down?

Still, I suppose a bigger problem always related to that 2.5 spur cable that is supplying a double socket that is now over loaded!!!


Oops that has been pointed out to me that I can not take the wiki on here as standard, and I suppose the 2.5 can take 27A depending on the mounting methods.

So my argument here is now flawed I give in, You win!

P.S. Still think it is safe tho in everyday circumstances

 

[Taylortwocities]

A nail through the cable will do it very nicely. And an RCD is only to be used as a supplementary protection device, the fuse/cb is the device that must trip/blow. The regs (and the detailed loading characteristic tables) define how installations must be carried out. They provide a methods of providing safe installations even under extreme and worst case scenarios.

When a competent electrician carries out work he signs a certificate that says the work has been carried out in accordance with BS7671.

There is no defence in court if you use the "I thought it would be OK to do it using the weedy wire spur method".

same as you would very rarely see two high powered appliances plugged into a double socket spured off the ring with 2.5 which would in fact do the scenario you are talking about and is much more likely, even to very rare!!!

But I see this all the time. Kitchen fitter runs spur to under worktop double socket. Into this is plugged a washing machine and tumble dryer.

 

[chapeau]

There is no defence in court if you use the "I thought it would be OK to do it using the weedy wire spur method".

But that wasn't his argument.

his argument is

1) The cable will never carry more than two amps because the light bulb fillament will not draw any more.
2) any damage to the cable which will bypass the protective device (light bulb filament) will be sorted out by the rcd.

So we return to what really matters i.e

Reasonable provision shall be made in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury

Is 'reasonable provision' using an RCD to prevent overcurrent in a cable?

Well. I don't think it is.

1) It's not what an RCD is designed to do. Not in its 'type rating' so to speak.
2) Failure rates of RCDs are unreasonably high

Add as you see fit.

 

[wtf69]

Well thanks for all your responses,
unfortunately I am of the same opinion (damn me!)
I do not think that the cable will ever pose a risk to my new property unless the RCD does in fact fail! I wont worry tho lol.
and from what I gather this can happen quite a lot of times!
thanks for all your replies, I really appreciate the answers and queries

Still doesn't rule out how some concealed spur 2.5 is deemed safe tho lol.

but there is plenty of posts on here relating to this so I can read them all to my hearts content!

Thanks again

 

[scousespark]

The 2.5mm spur (which I assume is rated at >26 amps as otherwise it was badly selected for the environment it is installed in) is protected by the two 13 amp fuses in the plug, these are proper protective devices.

You are protecting your 1.5mm spur with a light bulb, this is not a protective device. I think you now owe me a tenner

If a 2.5mm spur is run from a soket outlet, the protection is provided by the breaker, unless there is an FCU fitted. The FCU will protect anything on the load side. There will be a fuse in the plug top, but that protects the flex feeding the appliance.

 

[chapeau]

If a 2.5mm spur is run from a soket outlet, the protection is provided by the breaker, unless there is an FCU fitted. The FCU will protect anything on the load side. There will be a fuse in the plug top, but that protects the flex feeding the appliance.

So why can you only have a maximum of one double socket on an unfused spur in 2.5 t/e ? If what you say is correct there should be no limit.

 

[wtf69]

as we all know it is because of overloading the cable.
you cant spur off a spur becasue you then have an easier chance of connecting two high current devices, or indeed even more.
but this was part of my original argument, a concealed 2.5 cable is rated at 23A. a single spur could effectively have two high powered (13A) appliances attached and therefore overload the cable.

Still I guess that even having 26A running thru this cable will never casue it to catch fire, after all they always have a safety margin in

 

[Taylortwocities]

......... having 26A running thru this cable will never casue it to catch fire, after all they always have a safety margin in

I can tell you have never been Scuba diving. With an attitude like that you'd be dead in one dive.

As a DIYer you can make whatever assumptions you like about what safety margins there may (or may not be) in a particular method of doing things. After all, its only you and your family that could fry.

Electricians (good ones, anyway) tend to have a greater regard for the safety of others and their reputations.


Anyways, it looks like almost the end of this riveting topic, do enjoy trawling through old posts until you find one that agrees with you....

 

[wtf69]

yeah, I think I agree, the end of the topic is nigh!!!
and anyway, i have to get ready to go and watch the toon woop some coventry butt!!!

but if you can tell me what the current rating of a cable is buried into a wall / plastered in. as long as it is over 26A I bow down to your great expertise as been an electrical expert!

Thanks and good night!

Oh, and if you can link me to a site that shows me it is more then 26A it may save me some of my bedtime reading one night