10amp mcb's on light circits

[StaticPhilly]

hello all,

just a quick question,

just moved, house has 2 10amp mcb's for the lights
one circit, 4 lights
other, 4 lights

is it safe to use 10amps for these small circits? all the cable looks to be 1.00 3 core and 1.5mm 2 core

cheers,
Phil

 

[securespark]

There aren't any other lights you are unaware of on those breakers?

Is there more than one conductor leaving those breakers?

1.5 is OK on 10A.

 

[ericmark]

Normally no but it is not the cables that cause the problem but ceiling roses which are rated at 6A not 10A so to comply with the manufactures recommendations 6A is the normal max.

The regulations say we can use up to 16A for lighting but of course that would mean no ceiling roses being used.

Although it likely does not comply with regulations in real terms the only problem is likely is where a lamp which does not have an internal fuse (which they should have) goes short circuit (likely due to ionisation) then it can weld the contacts inside the BA22d lamp holder to the bulb.

It is unlikely to cause a fire.

So although it does not likely comply with regulations I would not really be worried about it.

 

[barnies]

how are ceiling roses rated at 6amps? how do you know that is there a way of calculating it?

 

[tonyelectric]

Most (but not all) are, it is generally pressed into the moulding somewhere, can't recall seeing one bigger than 6A but the older Rock plug in ones were 2A as were some of the older style dome with flange shaped ones

 

[barnies]

Most (but not all) are, it is generally pressed into the moulding somewhere, can't recall seeing one bigger than 6A but the older Rock plug in ones were 2A as were some of the older style dome with flange shaped ones

yea? and is the ceiling roses rated at 6amps becuase of the mcb rating? or how is the rating determined for a ceiling rose?

 

[Monkeh]

.. They're designed for a rating of 5/6A. The manufacturer states the rating and you follow it.

 

[DetlefSchmitz]

Bayonet sockets are manufactured to meet BS EN 61184. I assume this (originally British) specification defines the 6A limit. I can't afford the £120 to find out.

 

[tonyelectric]

Most (but not all) are, it is generally pressed into the moulding somewhere, can't recall seeing one bigger than 6A but the older Rock plug in ones were 2A as were some of the older style dome with flange shaped ones

yea? and is the ceiling roses rated at 6amps becuase of the mcb rating? or how is the rating determined for a ceiling rose?

Well i'm pretty interested and good at electrical history, but can't give you a definitive on this, the bayonet holder was one of the first electrical connections along with the edison screw. 6A is fairly recent and came with the modern wave of white MCBs, back in the days of fuses and black C50 breakers it was 5A, sockets could be had and still can in 2A for lighting but the smallest fuses of the ceramic re-wirable i've encountered are for 5A wire. The norm for lighting circuits on a domestic instal is 6A, but on a 1980s install at a local school the lighting breakers are 15A because they run vast banks of florrys, but but via 2A rock ashley roses wired with 2L1.5 pyro (which can take 21A)

 

[securespark]

Are we touching on that "13A socket" argument again?

The sockets are rated at 13A, but the terminals are used to connect wiring through which a potential current in excess of 32A could flow.

 

[tonyelectric]

In fairness all our british sockets are fantastically over engineered with oversized pins, but sooner that than the wobbly rubbish or 110volt friends across the pond have.

USA has 110V AC, except washington thats DC (sorry bad electrical joke, couldn't resist )

 

[barnies]

why are sockets rated at 13amps then and protected by a 32amp breaker?

 

[ajrobb]

why are sockets rated at 13amps then and protected by a 32amp breaker?

Probably because the CB protects the line cable and the plug fuse protects the socket internals. 32A is only carried between cables in the same terminal, not within the socket. (I think the CB disconnects the socket under fault conditions, so standard 13A sockets mustn't be connected to circuits capable of more than 32A.)

 

[barnies]

why are sockets rated at 13amps then and protected by a 32amp breaker?

Probably because the CB protects the line cable and the plug fuse protects the socket internals. 32A is only carried between cables in the same terminal, not within the socket. (I think the CB disconnects the socket under fault conditions, so standard 13A sockets mustn't be connected to circuits capable of more than 32A.)

why cant you connect the socket to something more than 32amps?? if the sockets internals are rated at 13amps only then???

 

[Monkeh]

why are sockets rated at 13amps then and protected by a 32amp breaker?

Probably because the CB protects the line cable and the plug fuse protects the socket internals. 32A is only carried between cables in the same terminal, not within the socket. (I think the CB disconnects the socket under fault conditions, so standard 13A sockets mustn't be connected to circuits capable of more than 32A.)

why cant you connect the socket to something more than 32amps?? if the sockets internals are rated at 13amps only then???

Because the terminals on the back are only rated for 32A?