6mm down to 2.5? design question?

[Clark3169]

Hi guys just want to run this one past a few of you genius dudes out there. Is the following ok...?

32amp mcb > 6mm cable > socket in loft > x2 2.5 (1 leg to underfloor heating in bathroom 13amp & 1 to summer element 13 amp both fixed) the socket has a shower pump permanently plugged into it with a 5 amp fuse. All RCD protected.

Now I know the 2.5 should have a 20 amp MCB normally but is this ok because they are run in parallel from that socket? Ie there isn't a section in the circuit that is just 2.5 with all the current going through. Thanks guys.

 

[telectrix]

if each fixed item ( ufh and summer element) is on a 13A FCU, then it's OK.

 

[Clark3169]

Brilliant that's what I thought. Thanks for your prompt reply, was in the middle of a debate about it and now my pint this evening is all paid for. Thanks again.

 

[Brightspark2]

There not in parallel as there not run to the same item of equipment there feeding seperate FCUs are they not?...

How far from the socket are the FCUs and how is it installed?. In certain circumstances over current protection can be omitted you need to look in the BGB.

Why dont you de rate down to 20A at the CU and then link them from socket to FCU to FCU?...

 

[monkeyelectric]

You could link the 2 2.5's to form a ring then you would have a lolipop

 

[Clark3169]

Brightspark, I understand what your saying. Is it possible to run from fcu to fcu? Would the first one not have more current than the manufacturer of the appliance intended?

 

[Clark3169]

Sorry that was a stupid I just thought about that. Connect the second one from supply side of first fcu of course. Sorry had a moment.

 

[Clark3169]

Anyways to answer your question. Walls can be chased but we can't lift tiled floor and each appliance is on opposite wall to the other. So I need two run two cables one down each side.

 

[Brightspark2]

Sorry that was a stupid I just thought about that. Connect the second one from supply side of first fcu of course. Sorry had a moment.

Ha ha yes thats it

But you say you cant, so I'd de-rate to 20A...