Water heater wiring advice please

[montrose]

Hi

I am about to install a 5kw undersink instant water heater for hand rinse basin. I was hoping to wire into the mains with a dp switch. Is this OK or do I have to take supply direct from fuse box with its own breaker?

Was hoping to keep as simple as poss, noted another post where 9.5kw was being used and advice was that building control would need to be notified, would this also be the case for smaller unit?

Cheers

 

[Lectrician]

Not sure what you mean by 'the mains' - I hope you do not mean the 'ring circuit' or 'socket circuit'?

A 5kw water heater requires it's own circuit and own consideration. You cannot pick up a feed from anywhere.

A new circuit does need to be notified to the BCO if you cannot self certify.

 

[ColJack]

not sure on the BC front with regards to the size, but as it's an installation in a kitchen it would be notifiable anyway, irrespective of the size..

for 5KW I would prefer to run a seperate supply, it's about 21A, so you'd have to use a 32A DP switch ( MK make them apparently ) and use a 25A-32A breaker in the board..

that's a big load on the ring if you try that, but it's only sparodic use.. it's not like you'd have it running for 20 mins... probably 30secs to a min to fill the washing up bowl? ( or are we talking instant tea water tap? )

 

[Lectrician]

MK and the rest of them

 

[ColJack]

looks like I can't read..
I'll asume that Angus is in scotland, and I'm unaware of the Scotish building regs with regard to electrics ( never had to use 'em myself ).

 

[montrose]

Thanks for replies so far. I am in scotland.

The unit will be in an office and hand rinse only so max use 1-2 mins? Was hoping to use the ring main if pos.

 

[Steve]

The unit will be in an office and hand rinse only so max use 1-2 mins? Was hoping to use the ring main if pos.

Not in my house, and definitely not in an office / commercial area.

It must be done right by someone qualified.

 

[Lectrician]

You cannot use the ring circuit - It is not designed to supply loads of that type.

 

[montrose]

Thanks guys.

Out of interest if I was to install 2 units, would could they both be on same circuit, and if so would 2.5mm cable do the job and 32A trip?

 

[RF Lighting]

Time to phone for a commercial electrician, me thinks

 

[ColJack]

lets see shal we?

21+21 = ????

DO THE MATHS..

2.5 cable can at BEST take 27A.. so you need 4mm cable for JUST ONE of them... on a 32A MCB..

 

[montrose]

Thanks guys

Have located a water heater circuit, getting electrician in to check it up to spec.

Cheers