New Miele Oven causing main RCD to trip. :(

[bongos]

He swapped a fuse in the kitchen board to rectify a lighting issue - a 6a to a 10a as on three occasions the fuse has tripped due to me powering on all the lights (14 x 50w mains, undercabinet led, plinth leds and an led 9 metre strip around the skylight)

IF those lights are all that are on the kitchen lighting MCB then I wouldn't have thought it would be enough to trip the 6A MCB (you would require upwards of 1380W to trip it). Although you have 700W of halogens the LED's won't take much power.

I hope the spark did test the earth fault loop impedance before whacking in the 10A breaker instead! Possibly a 6A 'C' type curve would have been more appropriate if it was tripping when you switch on.

 

[mfarrow]

A C6 breaker requires a lower fault impedance than a B10 breaker, but I agree that a C6 should have been considered. I don't really see the point of 10A breakers existing really, other than to fuel this bad practise.

 

[Spark123]

10A breakers exist for the same reason as any other fuse or protective device, there is a relatively big jump from 6A to 16A so I don't see a problem with having one round about the middle. 10A breakers are not only just used on lights!
It is up to the electrician to specify the correct one.

 

[Taylortwocities]

Also fitting a 10A fuse probably doesnt comply with the regulations, as the switchgear and fittings are only rated to 6a.

With respect, that is cr@p information.
How can you determine that?

Even if it is 1mm cable it is good for 10 amps. And the switches will be 10AX.

The only issue is determining that the EFLI is good for the upgrade to a 10A CPD.

 

[mfarrow]

With respect, that is cr@p information.
How can you determine that?

By looking on the back of the switch. Many are either 6A or 10A, but I'd prefer not to have to look.

Most standard fittings are rated at 15A, according to the regs.

 

[RF Lighting]

I always fit 10AX switches as standard, and occasionally 20AX for lighting.

Only the very cheapest nastiest switches are 6A rated. Besides, one switch will not be switching the entire circuit load.

 

[csh]

Surley the 6A rating is the switching load not the maximum protective device size.

 

[Aragorn84]

yes, but the protective device is there to protect the cabling the switches etc.

I didnt realise 10A switches were common, i thaught most were 6A, and the same for the bayonet light fittings and suchlike.

 

[csh]

No the protective device is there to protect the cable not the accessories. That is why you can put a 13A socket on a 32A ring final circuit[/quote]

 

[Aragorn84]

The device attached to a 13A socket cant draw any more than 13A, becuase theres a fuse in the plugtop (assuming no-ones shonked it up with a bolt)

A device attached to a 6A light switch could happily draw 20A (for example) unless the protective device tripped out...

So surely the CPD is protecting the fittings as well as the cable?

 

[csh]

A double socket could draw 26A through 2 plug tops the protective device is to protect the cable not the accessory

 

[mfarrow]

6A is the rating of the switch - most don't specify whether this is switching or continuos rating.

Either way an overload on a 6A switch could cause the switch to overheat, melt, burn etc.

I would hope a double socket is capable of 26A, as that's what it's designed for. You're right in that the socket itself isn't protected, however it's in such close proximity to the plug fuse that I doubt it's applicable in this discussion.

 

[csh]

If I remember correctly MEM double sockets are rated at 22A.

 

[mfarrow]

I'm surprised they couldn't find the time to squeeze the extra 4 amps out of that.

Still, with at least two loads connected to a double socket you can take into account some diversity. With a fixed lighting final circuit fed from one switch, you can't.

 

[skenk]

I'm surprised they couldn't find the time to squeeze the extra 4 amps out of that.

The discussion about the rating of a double socket has been had before. If I remember correctly, most aren't rated to 26A. I think MK are (but even then not for continuous use for extended periods).

Still, with at least two loads connected to a double socket you can take into account some diversity. With a fixed lighting final circuit fed from one switch, you can't.

You wouldn't use diversity deciding which switch rating would be suitable but you would limit the load at the circuit design stage.