wiring a light directly into a 13 amp socket

Hi

My father claims it's perfectly safe to wire a 3 amp light directly into a 13 amp socket (rather than using the plug supplied with the light). I've heard different -- can someone here give me a definitive answer?

What's the danger of doing something like this? (So I can finally convince him).

Cheers,
Graham.

the issue is fusing

3A rated flex wired to a 32A cuircuit with no protection is insane and under fault conditions could well melt

if you do want to wire it to the socket then provided the socket is on the ring you can wire from the socket to a fused conenction unit using 2.5mm twin and earth and fit a 3A fuse in the fused connection unit

But you most certainly can not wire the light flex straight into the back of a plug socket!

When you say the plug supplied with the light, do you mean a standard 13A plug or a lighting-style plug (round pins)? It would be safe to use a 13A plug with a 3A fuse.

graham365 said:

My father claims it's perfectly safe to wire a 3 amp light directly into a 13 amp socket (rather than using the plug supplied with the light). I've heard different -- can someone here give me a definitive answer?

Click to expand...

Does your Dad ride a horse by any chance ?

Definitive answer on this...ABSOLUTELY NOT

The light must be fused according to it's designed load, therefore it must be fused to 3A max, therefore should be connected via a standard plug or a Fused Connection Unit, either used should contain a 3A fuse.

AdamW said:

When you say the plug supplied with the light, do you mean a standard 13A plug or a lighting-style plug (round pins)? It would be safe to use a 13A plug with a 3A fuse.

Click to expand...

Standard 13A plug, with 3A fuse.

Thanks for the info, guys. I'll let him know.

Just out of interest, what kind of fault would make the wire melt? I've often heard people make comments like "if something went wrong" or "if a fault occurred". What kind of thing are we talking about?

Cheers, and thanks again for your help.

Well - actually a melting wire is extremely unlikely - a short circuit would cause the MCB/fuse protecting the ring to operate so quickly that the wire would never have a chance to melt.

What could happen, although still v.unlikely is a partial insulation fault (e.g. chafing or other mechanical damage to the flex) that causes a current <30A but too much for the cable to flow. Since the melting point of copper is, IIRC, 900 deg C, what will happen is that the insulation will melt, and maybe catch fire.

You should have protection to prevent this, rather than relying on the fact that the odds are in your favour.

I had a similar discussion with my father last year - he had a TT supply and therefore a whole-house RCD. He wired flex with a trailing socket on it (trailing across the concrete floor of the garage, I might add) directly onto the incoming terminals of the RCD to power the freezer to avoid problems with nuisance trips. It's sorted now though.

yeah on a short flex to a light melting is unlikely because in the event of a short the fault loop would still be low enough in reseistance to take out the mcb

but with a long bit of 3A flex its definately possible that your short cuircuit current could be insuffiant to fast trip the breaker and the plastic would start to melt

a wire melt on a short flex would require an overload and not a short which is fairly unlikely but possible

the other thing is whereever a flex leaves fixed wring you need a cord grip to stop it being ripped out and the backs of sockets don't have theese (fused connection units generally do)