Often new houses have 5-amp sockets installed on a lighting circuit which have switches just like normal room lights. Thus you can install table or floor lamps which can be turned on "on the wall".

Is it SAFE to connect (via a non-fused 5-amp lighting plug) to such a (5-amp) circuit, a table lamp that originally came with a 3-amp fuse?

The lamp only has a (maximum!) 100-watt bulb, so that in itself will not overload things, but is it possible that the connecting cable itself is only 3-amps - thus weaker than the main circuit fuse?

I just want to check whether i can cut off the existing 13-amp plug fitted with a 3-amp fuse (via the 13-amp ring-main), and replace it with a 5-amp (round pin) plug with no fuse on the lighting circuit????

Trying to be extra dumb/safe!!!!

mb

not being dumb matey....just clued up...if you dont know then not worth the risk..

ok.....if you have a table lamp and it is fitted with a plug, you can put a 5a fuse and use it in any mains socket......if you have 5a sockets in the wall that are swithed either at the normal light switch or at source. then yes, you can chop off the mains plug and fit a 5a lighting plug to the lamp flex and plug in...it it what its desighned for...table lamps that have mains plugs on are the same with a different plug, just the fuse is changed to 5a for discrimination.........so as the small round sockets are already on a 5a lighting circuit no need for discrimination.

Ed,

my worry is that as the table lamp came with a 3-amp fuse (rather than a 5-amp one) in a normal 13-amp square pin plug, there may be some part (flex, wire, connector, bulb?) in the lamp that is limited to 3-amps!

Replacing the 13-amp plug (with a 3-amp fuse) with (effectively) a 5-amp fused circuit could thus potentially overload things.

I would hope that the regulations state that all lamps can hack 5-amps, thus no-problemo! - but i just want to make sure?

Cheers,

mb

By my sums W/V = I So 100 (watt bulb) / 240 (volts) = .417 Amps

Looks like a 100 w bulb draws only about half an amp so you'd be more than ok ;)

D

if you use a 60w bulb you will only draw .25amps so even better!

the 3A fuse was put there to discriminate.....(from 5amp.)you can go right ahead and put the lighting plug on, it wont blow up, im assuming the flex on the lamp is 1.0

If the flex is what was supplied with the (100W) lamp then it doesn't matter what plug/fuse you have, the flex will stay safe for the lamp. After all the lamp will use no more power than it used to

Unless the socket is different (?) there is no real point even changing the plug.

Deano

Diesel,

sure, under normal operation, a single bulb is not going to overload even a 1-amp fuse - but if some of the other bits go wrong (flex, holder, whatever) then it potentially can!

Ed,

yup, i reckon that it is basically down to the flex - what does "1.0" mean (mm2?), (and how can i tell - bought from B&Q on Thursday)? Also, being very dumb, what does "discriminate" mean in an electrical context?

***snip after Scoobynet hung***

dsmith,

it will be a new table lamp, on an as yet un-used 5-amp socket (after cutting off the existing 13-amp plug).

I guess that i am just being too paranoid, and there should be no problem plugging a table lamp into a 5-amp lighting circuit - but better safe than sorry!

Cheers for all the help so far,

mb

disrimination is...in electrical terms ......the order of fuses
ei:- 100amp down to 60a to 40 , 32, 16, 13, 5, 3.
you only ever fuse down otherwise it will not do its job in breaking if it is higer then the previous fuse in line....this is known as discrimination.

the '1.0' was flex size dia. of cable. this is used on lighting circuits like in a baton set from the rose to the bulb holder, usually only got two core cables (red/blue) some are 1.5 with an earth in the flex, no need for larger on light circuit ( unless of coarse its a 2kw search light )It is safe to put an unfused 5a small round pin lighting plug on and use it, im assuming i is switched on the wall by the entrance or exit, and is wired to the lighting circuit...in fact it is more safe than pluggin into a ring main with a only a fuse to rely on!