Existing 5amp switches on 6amp circuits

[Paul P]

Hi This may seem a silly question, I heard a rumer that you can't keep the old 5amp light switches if you replace a consumer unit and fit 6 amp mcb's. I think it is a load of tosh. Does anyone have a definite answer?

 

[hasel5]

O load of tosh mate

 

[Sintra]

The switch is limited to the load that it switches not the load of the circuit. I would say it's a load of tosh.

 

[7029 dave]

Rubbish

 

[Flanders]

As long as the load connected to the light switch is 5 amps or less then I can't see a problem

 

[Plonker 3]

Imagine a 13 amp socket on a 16 amp radial circuit, it's not dissimilar.

 

[Octopus]

Or a 13A socket on a 32A circuit!

 

[Darkwood]

Paul P... exactly where did you hear this rumour?

We have a lot of ears to the ground on here and this is a new one on me although complete rubbish- half the equipment in any installation wouldn't comply if this scenario was correct

 

[Engineer54]

Hi This may seem a silly question, I heard a rumer that you can't keep the old 5amp light switches if you replace a consumer unit and fit 6 amp mcb's. I think it is a load of tosh. Does anyone have a definite answer?

Have you been listening to one of those 17 Day whizz kids by any chance?? lol!!

 

[Sintra]

It's probably another way of scamming the poor customers after they have been convinced to change their perfectly good consumer unit.

 

[old_sparky_RE]

http://www.electriciansforums.co.uk...85039-light-switches-mcbs-size-reg-536-a.html

A question I posted 2weeks ago as we were being inspected and Reg 536 was quoted as the reason for failure!
Overcurrent is fault current or overload current (see430.3), so with this in mind all 5A switches must be fitted with 5A MCB's !!!!!!!!
Common sence is NOT allowed. Do as I say.

 

[Engineer54]

Apart from being a complete load of rubbish, you try finding a 5A MCB!! lol!!

This inspector clearly doesn't understand the basics of what he's inspecting. Did he put anything down in writing by any chance??

Oh and by the way, over current and fault current are completely different and have completely different and separate mechanisms within MCB's (or MCCB's etc) eg thermal & magnetic, for the protection for each type of current.

As for the minimum sized lighting cables, as related too in you're link, this is common practice on larger sized projects, and we too have 2.5mm minimum for lighting circuits, but that is only for ''Fixed or Installation wiring, not factory supplied equipment etc.

If anyone else is sacked because of these idiots, take the company to court for unfair dismissal, ....and then see what happens!! lol!!

 

[pepparz]

ive got loads of 5 A MEM MCBs there type 1 to BS3871 category of duty M6, order code; 51QEB.

 

[Engineer54]

ive got loads of 5 A MEM MCBs there type 1 to BS3871 category of duty M6, order code; 51QEB.

Will they fit a modern CU though?? And come to that, do/will they comply with 17th BS7671?? Those Type 1/ 2/ and 3's must have been out of production for years now....

 

[Kamikaze]

You can still get a load of 3A mcb’s. :smile5:

 

[old_sparky_RE]

In reply to E54

All recorded and 'repaired' with 277v 20A switches c/o US Goverment funds.

I know and understand the difference and functions of an OCPD it's just the 'gate keeper' software we have stops me adding those smiley face things to show when I'm being pedantic !!

US contracts company for DOD (US Goverment), employment contract signed in Dubai, working in/on NATO, Crown and US soil in Afghanistan... likleyhood of winning anything ZERO.

 

[Engineer54]

In reply to E54

All recorded and 'repaired' with 277v 20A switches c/o US Goverment funds.

I know and understand the difference and functions of an OCPD it's just the 'gate keeper' software we have stops me adding those smiley face things to show when I'm being pedantic !!

US contracts company for DOD (US Goverment), employment contract signed in Dubai, working in/on NATO, Crown and US soil in Afghanistan... likleyhood of winning anything ZERO.

You have never mentioned where you are, or what Code or Reg system you are working too. Unless i'm missing something, i'm pretty sure everyone here thinks you're talking about a UK situation. Not sure how you retrofitted American typical 20A toggle switches in a UK back box mind!! lol!!

 

[Flanders]

Imagine a 13 amp socket on a 16 amp radial circuit, it's not dissimilar.

But a 13 amp socket will only have a max load of 13 amps as the fuse in the plug top would protect it,(unless someone has shoved a euro plug in it ) but a light switch does not have any local over load protection so although as I stated, as long as the max demand on the 5 amp light switch does not exceed 5 amps then there is no problem but if the switch is supply a load of 6 amps then it does not comply .

 

[MDJ]

Total Rollocks, the amount of 32 amp Switch fuses bolted onto 200 amp busbar chambers and the cables only 6mm2 is very common, so a 5 amp switch connected to a 6 amp MCB is no problem at all, what a silly thread.

 

[HappyHippyDad]

The switch is limited to the load that it switches not the load of the circuit. I would say it's a load of tosh.

I've thought about this before and thought about asking the forum.. Its not rare to see the switch with a neutral in it which means if its at the beginning of the circuit its taking all the current, not just what its switching?

Or a 13A socket on a 32A circuit!

Also thought about this! :smiley2:

I'd be interested to know how we can use sockets rated as 13A when the current running through them could be as much as 32A? Even though the 32A is unlikely, it's certainly possible to be well over 13A at times. I guess the sockets are able to take much more than 13A, but it seems a bit misleading to rate them as such.

 

[Flanders]

The reason only 6mm cable is used for these switched fuses is because you only have to install the cable from the bus bar big enough to carry the maximum demand of the circuit, in this case 32 amps (as long as the switched fuse is connect within 3 meters of the bus bar )

 

[Flanders]

I've thought about this before and thought about asking the forum.. Its not rare to see the switch with a neutral though which means if its at the beginning of the circuit its taking all the current, not just what its switching?



Also thought about this! :smiley2:

I'd be interested to know how we can use sockets rated as 13A when the current running through them could be as much as 32A? Even though the 32A is unlikely, it's certainly possible to be well over 13A at times. I guess the sockets are able to take much more than 13A, but it seems a bit misleading to rate them as such.

The socket outlets them-self's would only pull a max of 13 amps As the fuse in the plug top would prevent any more load, I would guess the terminal would be ratted at 26 amp (two plugs in a double socket) it would be imposible to pull 32 amp through a socket unless you put some kit-kat rapper in place of the fuse

 

[Silly Sausage]

I'd be interested to know how we can use sockets rated as 13A when the current running through them could be as much as 32A? Even though the 32A is unlikely, it's certainly possible to be well over 13A at times. I guess the sockets are able to take much more than 13A, but it seems a bit misleading to rate them as such.

That would have to be a broken RFC running at maximum capacity.
Not having read BS1363, I can only assume each individual socket (the part plug fits into) is rated at 13A.
The cable connections must be rated higher, maybe 20A; but to repeat, I haven't read BS1363!

 

[Sintra]

I've thought about this before and thought about asking the forum.. Its not rare to see the switch with a neutral in it which means if its at the beginning of the circuit its taking all the current, not just what its switching.

Think you need to rethink this

 

[HappyHippyDad]

Think you need to rethink this

Have I put my foot in it big time!! :smiley2:

I'm actually in the middle of something that is taking about 90% of my concentration so will think later!

 

[HappyHippyDad]

Think you need to rethink this

I've rethought and rethought and I cant think anymore.

(nearly) all the current 'could' go through the switch (circled)!!

Put me out of my misery and tell me what is the obvious thing that I'm missing Sintra!

View attachment IMG_20131219_0001.pdf

Apologies for awful drawing, just a bit rushed.

 

[overskilled]

I'd go with a difference in labelling - exhibit A) terminal strips, bought some from one wholesaler, labelled as 5amp, same size elsewhere...packaging labelled as 6amp....
3871 followed 3036 ratings, but they changed for 60898...and I cannot find out the reason why through a quick google...I'd guess something to do with powers of 2 or something...

Also double sockets are NOT designed to support 26A draw...MK did some testing and the most their sockets (Which are over specced) could thermally support was around 19Amps sustained, much over 20 caused thermal damage over time (brown heat damage, deformation due to heat) 26A draw got things rather hot, very quickly and the conclusion was that it would have led to a fire.

 

[spark 68]

I've rethought and rethought and I cant think anymore.

(nearly) all the current 'could' go through the switch (circled)!!

Put me out of my misery and tell me what is the obvious thing that I'm missing Sintra!

View attachment 21861

Apologies for awful drawing, just a bit rushed.

Hi HHD,

In your drawing the supplies are merely looped at the switch , using the switch as a junction box, the current actually running through each switch is only that for each lamp/s each switch controls.

Unless you only have one switch controlling every lamp in the building lol

 

[HappyHippyDad]

Hi HHD,

In your drawing the supplies are merely looped at the switch , using the switch as a junction box, the current actually running through each switch is only that for each lamp/s each switch controls.

Unless you only have one switch controlling every lamp in the building lol

What a patient reply Spark68 , thanks..

I have to confess I thought of the switch (and everything within it) as being rated at what it stated, but its just the switch itself!! I wonder what the actual terminals within the switch are rated at?

 

[spark 68]

What a patient reply Spark68 , thanks..

I have to confess I thought of the switch (and everything within it) as being rated at what it stated, but its just the switch itself!! I wonder what the actual terminals within the switch are rated at?

No bother hhd,
The terminals in the switch will be rated greater than the 1 or 1.5mm cable usually used, besides which they are mainly just a means to secure the conductors (together in this case) rather than being an actual link in the current path.

Edit: in the context of looping through