Pretty sure my cps assessor was wrong

[AndyL]

So I had my yearly assessment today with my friendly local engineer. He was fair enough but there was 2 points he pulled me on that have niggled me because I am sure I was right.
Would like some other opinions please.

Firstly a 60 Amp TN-S supply to a domestic property. ... what is the minimum size tails?
Secondly do you guys tick the double insulated box in S.O.I because of the meter tails?

I'll let you know who was in each corner after a few replies so as not to sway your decision ( as if it could)

 

[Ian1981]

My thoughts on clipped direct is that it may apply between the head and meter where there is no enclosure, enter them into a board they are no longer clipped direct and should be down rated.

What reference method would you use for down rating them?

 

[AndyL]

My thoughts on clipped direct is that it may apply between the head and meter where there is no enclosure, enter them into a board they are no longer clipped direct and should be down rated.

But surely all clipped direct cables eventually go in to an enclosure

 

[westward10]

What reference method would you use for down rating them?

I would use the column from 4D1A for cables contained in conduit or trunking, Reference B.

 

[westward10]

But surely all clipped direct cables eventually go in to an enclosure

Not between the head and meter they don't.

 

[Dave OCD]

25mm tails, what's the point when the incoming supply is 16mm.

 

[stevethesparks]

But surely all clipped direct cables eventually go in to an enclosure

My thoughts too, with that logic, clipped direct cannot exist.

 

[Ian1981]

Not between the head and meter they don't.

Think he means installing twin and earth buried in a wall then into the db would be considered reference method c clipped direct.
I think that's what he means anyway

 

[westward10]

No talking of tails, yes they can be clipped direct between head and meter but they are no longer clipped direct within the CU.

 

[Ian1981]

That would mean 16mm tails CCC would be 76amps reference method B and maybe couldn't be adequately protected by a DNO 80amp fuse , tho load profile maybe acceptable If clipped direct then 87 amps

 

[westward10]

Not actually looked the ratings up.

 

[Dave OCD]

But like any cable these are continuous ratings, I'd be amazed if domestic meter tails ever see 80amps.

 

[7029 dave]

The bloke does not know what he is talking about. Lots of sparkys will use 25mm no matter what size the supply cut out is, I will not even up grade tails with a 80 amp cut out. ( you lot may have to depending on installation method)

 

[AndyL]

He actually said it had to be 25mm because the cuu main switch is rated at 100A.

 

[Ian1981]

He actually said it had to be 25mm because the cuu main switch is rated at 100A.

that makes no sense to me

 

[7029 dave]

He actually said it had to be 25mm because the cuu main switch is rated at 100A.

Well it will never reach that with a 60amp cut out. lol