Tail upgrade unconventional set up

[Dal Roberts]

Been to look at a job, the property is a 1st floor flat 3 bed , the service head is situated downstairs in communal external meter cupboard with 16mm tails (standard tails not PYRO 10mm which I have seen before) rising to the flats CU more than 3 metres away to board which is a BS3036 board, customer requires a 10.5kw supply for new shower, they don't want to spend out on a new board and the only way I would be able to offer install under section701 would be to henley block at the CU in flat itself and feed the existing BS3036 and fit alongside the BS3036 a shower CU 50amp with 30ma RCD, in this situation surely the tails would need to be upgraded to 25mm and the max of 3 metres rule would also apply, any suggestions would be appreciated  

 

[ProDave]

Isn't it just  the lack of isolator at the supply is the issue? If there were a switch fuse with an 80A fuse in it, then the 16mm tails are okay, so can you not just fit a switch fuse in the supply cupboard?
 

 

[Lurch]

I would as a minimum add a switch fuse at the meter end so as @ProDave points out, this will allow you to fuse down to a relevant rating for the tails. I would strongly advise the client though that a board change would make more sense in the long run, for the price difference. I'm doing similar on another job, client wanted a new circuit but the CU was in a bit of a state and there were a few remedials needed to get it something like before I could add a circuit, and then an RCD in another enclosure, at which point we might as well just change the board.

 

[Dal Roberts]

Thanks guys , that's been really helpful , it's a flat so the demand is not high and only 1 ring final and LTG circuit on the 3036 board , I will try to convince him of a new amend 3 board and fuse rate the 16s . Have a nice weekend 

 

[Adrian]

But they have the same appliances as any other house ie cooker, kettle ,microwave, washing machine,TV,vacume cleaner ,ect  ect  just because it has one ring circuit don't assume the load is less than a property with several circuits.

 

[Dal Roberts]

Thanks guys , that's been really helpful , it's a flat so the demand is not high and only 1 ring final and LTG circuit on the 3036 board , I will try to convince him of a new amend 3 board and fuse rate the 16s . Have a nice weekend 

 

[Dal Roberts]

That's true obviously max demand would go on the cert, I doubt they'll be pulling more than 16kw unless there filming masterchef in the flat and the cooker diversity goes out the window 

 

[Lurch]

But they have the same appliances as any other house ie cooker, kettle ,microwave, washing machine,TV,vacume cleaner ,ect  ect  just because it has one ring circuit don't assume the load is less than a property with several circuits.

But bear in mind that excluding all electric cooking (not just a single electric oven) and heating most houses would struggle to use more than 16A. My own house is a reasonably sized 4 bedroom but has 1 ring and 1 lighting circuit and an unused immersion circuit and the main fuse is a 30A BS88. Been fine for years.

So I'd look at it the other way, just because you have a huge house don't assume that the max demand is any more than a 1 bed flat!

 

[Murdoch]

How daft some people can be, as can the sparks viewing the job....

A new cu in the flat or all the faffing around with Henley blocks, tails, a separate new rcd cu etc.....

Give them a price for the Henley etc and the "upgrade" price to a new cu...... The difference won't be as much as you think....

 

[Dal Roberts]

True Murdoch , the job starts Monday , and he has gone for the new CU ;o)