Kitchen extractor supply cable

[regsmyth]

I am taking a spur from the kitchen 2.5mm ring, to a DP FCU. Can the cable from the FCU to the connection unit next to the extractor be 1mm, or is it best practice to use 2.5 in case anyone in the future decides to connect something more powerful to it? The connection unit itself would be either an unfused plug, or a hard wired jobbie.
Thanks for all comments.

 

[ban-all-sheds]

I am taking a spur from the kitchen 2.5mm ring, to a DP FCU. Can the cable from the FCU to the connection unit next to the extractor be 1mm, or is it best practice to use 2.5 in case anyone in the future decides to connect something more powerful to it?

Can't be more than a 13A load, so 1.5mm² will be fine.

The connection unit itself would be either an unfused plug, or a hard wired jobbie.

What sort of unfused plug?

Not a BS1363 with the fuse replaced by a link, I hope...

 

[regsmyth]

I was under the impression that once the appliance was protected (by the FCU), you shouldn't have another fuse "down the line", so the connection by the extractor could be either permanently wired in, or use an unfused plug, but I don't actually know what that is, so I was going to look into it.

BTW, does your reply also apply to the dishwasher under the worktop? ie 1.5mm supply from the FCU (yes a different one).

 

[stargazer]

Reg, have a look here and all will become clear.

 

[regsmyth]

Thanks Stargazer, there is just so much good stuff on this site! But my question is to do with the cable size. bas says 1.5mm is fine for the extractor as there can't be more than a 13A load, so does that mean that 1.5mm is also fine for the dishwasher?

 

[stargazer]

The cable used from the load side of the FCU should be appropriate to the rating of the FCU fuse and intended load.
1.5mm is suitably rated for the maximum current draw of 13 amps set by your FCU, but common practice is to use 2.5mm for the load side when wiring kitchen appliances with a heavy current draw.
So I would wire as follows:-
FCU for extractor fan fused at 5 amps – 2.5mm to supply side of FCU, 1.5mm from load side.
FCU for dishwasher fused at 13 amps – 2.5mm to supply side of FCU, 2.5mm from load side.

 

[Taylortwocities]

And Reg, dont forget to notify your local authority before you start work

 

[regsmyth]

FCU for extractor fan fused at 5 amps – 2.5mm to supply side of FCU, 1.5mm from load side.
FCU for dishwasher fused at 13 amps – 2.5mm to supply side of FCU, 2.5mm from load side.

Thats just what I'll do. But now it's got me thinking and confused.
If 1.5mm is ok for up to 13A, then as you infer, it's possible to use it for "lighter" use domestic appliances, so I was just thinking about power and amps and stuff and I thought W = VxA, so a 3kW kettle/230V = 13A so why doesn't the fuse blow?
A little knowledge....
But at least I've worked out how to do the quote thing!

 

[stargazer]

Reg, I know it sounds illogical, but a 13 amp fuse will not blow when you run 13.1 amps through it. You’d be surprised how much overload it will tolerate and for how long before it gives up the ghost. Kettles are normally rated below 3KW, so why don’t you boil one, make yourself a coffee, and have a read of the link below. It’s a long article but worth the effort.
http://www.kevinboone.com/cableselection_web.html

 

[regsmyth]

That's a great link too. I have quickly scanned it and will look at it properly......later.
Thanks again to all.

 

[ban-all-sheds]

so why doesn't the fuse blow?