Kitchen Appliance circuit

[Snapester]

Designing a kitchen appliance circuit, i plan to feed a bank of grid switches with a 6mm T&E fed via a 32A MCB, then each switch will have a 2.5mm cable to a fcu supplying an under counter appliance.
My main question is, is it ok to change down to 2.5mm and then feeding the FCU? As the cable cannot be overloaded as the main load is connected to the FCU at position?

Regards

 

[i=p/u]

but the 2.5 is protected by 32A, but im talking basics so hold up for an expert

 

[GLENNSPARK]

yes.....minimum feed for an FCU is 1.5mm by the way......

 

[GLENNSPARK]

but the 2.5 is protected by 32A, but im talking basics so hold up for an expert

come on I=P/U....you gonna try stuffin 4mm or 6mm into the back of an FCU?...lol.....

 

[Snapester]

Is that down to the reg which states 1mm is only allowed on lighting power circuits?

 

[telectrix]

can you get 2 6mm cables in each terminal of the switches?

 

[Snapester]

I=P/U if the connected load is protected by the FCU then the 2.5mm cannot be overloaded hence protected.

 

[telectrix]

come on I=P/U....you gonna try stuffin 4mm or 6mm into the back of an FCU?...lol...

i read it as 6mm to switch bank, then 2.5mm to each FCU. but doubt if could link switches in 6mm

 

[Snapester]

telectrix yes that is a valid point! Maybe i will run a 4mm 20amp radial i will check the calcs!
I should have thought about that one damn! This is why you guys are good to run it through with!

 

[i=p/u]

sso what stops me from adding a light off 11kw shower in 1.5 , sure the light will only pull 40W... thats my point..

 

[J&M Electrical]

Why not just run a Ring in 2.5? even if it is only to the grid switch it will be hell of a lot easier to terminate. You could keep it on a 32A Breaker then.

 

[GLENNSPARK]

come on I=P/U....you gonna try stuffin 4mm or 6mm into the back of an FCU?...lol...

i read it as 6mm to switch bank, then 2.5mm to each FCU. but doubt if could link switches in 6mm

yes...it was meant in jest more than anything else....

 

[Snapester]

I=P/U nothing as long as you protect it via FCU

 

[i=p/u]

so i take it hes in a commercial kitchen with lot of appliances and wants to switch them from the door.. so how would you go about this.

and detailed for the impaired glensparks

 

[i=p/u]

but what about the 2.5 from the switch to the fcu???

 

[ipf]

Why not just run a Ring in 2.5? even if it is only to the grid switch it will be hell of a lot easier to terminate. You could keep it on a 32A Breaker then.

Incorporate general sockets too, if required.

 

[i=p/u]

id run a radial for each to minimize inconvenience, that just me a professional

 

[D Skelton]

Why not run two seperate 2.5mm radials protected by two 20A breakers each feeding half of the switches within the grid then run your circuits in 2.5mm from each grid switch straight to each socket outlet? Also, no need for FCU's, unless the appliances have no plugs.

 

[DaveyD]

but what about the 2.5 from the switch to the fcu???

On this radial circuit that 2.5 run from the appliance switch can only ever be subjected to maximum 13a being drawn through it because the SINGLE appliance will be conected to the 2.5 via the FCU or a standard plug - either of which take a maximum 13a.

 

[D Skelton]

On this radial circuit that 2.5 run from the appliance switch can only ever be subjected to maximum 13a being drawn through it because the SINGLE appliance will be conected to the 2.5 via the FCU or a standard plug - either of which take a maximum 13a.

What about in the event of a short circuit at the FCU?

Edit: Or a fault at the FCU that somehow results in 32A and no more being drawn through the 2.5mm cable?

Fire hazard me thinks

 

[Octopus]

How about the good old 2.5mm T&E ring protected by a 32A breaker in the board. Got to be easier!

 

[Snapester]

There was an article in NICEIC mag about putting grid switches on ring and how it needs to be balanced at the middle of the ring, i will see if i can dig it out! Also the grid switch is one point so i wouldn't want to run a ring to one point?

 

[Octopus]

There was an article in NICEIC mag about putting grid switches on ring and how it needs to be balanced at the middle of the ring, i will see if i can dig it out! Also the grid switch is one point so i wouldn't want to run a ring to one point?

I wasn't suggesting keeping the grid switch at all!

 

[sedgy34]

your 2.5 cable will be on a 32a mcb also the grid switch terminals are rated at 20amp again on a 32a mcb



you could run seperate 20amp radials and use a dp switch with neon and a un switched socket below your appliance will be fused in the plug that comes with it

 

[Snapester]

Yes sedgy34 but the switch is only supplying a 1x 13amp appliance so full load of 32a isn't flowing through the switch.
Sorry Murdoch misread you post, the client has stipulated a isolation bank of switches.

 

[i=p/u]

move the mcb to the exit:. ive seen this in older installations but not in new ones....

 

[Des 56]

There was an article in NICEIC mag about putting grid switches on ring and how it needs to be balanced at the middle of the ring, i will see if i can dig it out! Also the grid switch is one point so i wouldn't want to run a ring to one point?

Why not ?

If the grid assembly is the only outlet on that circuit,the ring will be almost perfectly balanced

I would say keep it simple 2,5mm ring to the grid assembly on its own 32A mcb,
If you want ,you can fit grid fuses as well for the loads and outlet plates for the appliances

I would also suggest the 20 amp rating refers to the switch contacts not the supply terminals

 

[telectrix]

i'm with des and murdoch here. 2.5mm RFC to grid. as in K.I.S.S.

 

[Snapester]

run a ring to a grid switch?

 

[Des 56]

run a ring to a grid switch?

--- assembly,yes

 

[Snapester]

It seems a little strange running two ring legs from the CU straight to the grid plate? Surely 1x 6mm will be exactly the same? I fail to see the difference apart from conductor size?

 

[J&M Electrical]

run a ring to a grid switch?

Yes, its 1 switch but the switch is effectively 6/9/12 points or however many Appliances your switching.

 

[Snapester]

I gather the whole idea that the switch supplies x amount of points but why run 2x 2.5mm 20m to the grid whereas 1x 6mm will be more than adequate?

 

[Des 56]

It seems a little strange running two ring legs from the CU straight to the grid plate? Surely 1x 6mm will be exactly the same? I fail to see the difference apart from conductor size?

Do 2 installations,one with a 6,0mm radial supply and another with 2,5mm ring.fit the grids then decide which was the easiest and better quality arrangement

 

[Snapester]

Yes i may do this.

 

[DaveyD]

It seems a little strange running two ring legs from the CU straight to the grid plate? Surely 1x 6mm will be exactly the same? I fail to see the difference apart from conductor size?

Would you even get two 6mm conductors in? If its MK, crabtree or GET I could'nt do it.

 

[Snapester]

Well according to Mk Data sheet 2x6mm is possible! Although i think looping with 4mm will be a better option and just having main feed as 6mm.

 

[Des 56]

You have had many opinions, so all I can now say is, everyone to their own ways, hope it works out for you

I will think of this thread the next time I'm putting those little loops across the grid switches

 

[Snapester]

Could always use a 6mm wago connector in the backbox and loop off with 2.5 to each switch!

 

[DaveyD]

What about in the event of a short circuit at the FCU?

Edit: Or a fault at the FCU that somehow results in 32A and no more being drawn through the 2.5mm cable?

Fire hazard me thinks

OK - I'm not tring to be contentious here - I'm sure you are more experienced than me; but are you saying that my reply is incorrect? I was thinking say for example on a 32a radial in 4mm T&E. You are permitted to spur off to one double socket in just 2.5mm T&E. We are not suggesting that 2.5mm will be ok at 32a.
Happy to be corrected so long as it's constructive.