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Discuss 16mm SWA tails maybe 9 mtrs from isolator on a 100a supply, and other concerns - EICR opinions in the UK Electrical Forum area at ElectriciansForums.net

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This has come up many times before and after a couple of hours reading previous posts I'm no closer to deciding on a code, note or nothing at all.

BS7671 allows 16mm tails on 100A fuse if demand is less than the cables CCC, I have 16mm at 94amps and the max demand is 60a.

From a previous post I've read UKPN state switched fuse OR ISOLATOR within 3mtrs.

Would you code, mention or no mention this?
 
You are assesong the job as per BS7671, nithing else so UKPN has no bearing on it. What you have to ask yourself is will the maximum demand ever chamge in the future seeing as the incoming fuses will allow it.
 
Thanks Guys,

I agree Dillb, and it is feasible as separate 6mm cable has been run for hob and oven, new home owners may decide to install induction hob and higher rating oven.

It is a gas hob atm and 13amp SFS for oven.
Oven at higher rating is probably unlikely as most modern ones are 16A max.

Either way it didn't sit right with me as I would have installed switched fuse at 80A. Still unsure on code though?
 
Im going to try to attach photos..
Other areas of concern are:

1) Un-enclosed SWA conductors - I guess it could be argued the meter cabinet is an enclosure opened by key. so maybe C3 not C2?

2) Main earth uses gas supply = C2
From suppliers terminal they have 10mm to first earth terminal, the 2x 10mm goes to water bond, the 2x 2.5mm go to SWA amour. Nothing connects to the other earth terminal! Which holds the 2x 16mm from the SWA and 2x 10mm Gas bonds. Therefore other than the gas the earth path is the 2x2.5mm to the amour.
 
[ElectriciansForums.net] 16mm SWA tails maybe 9 mtrs from isolator on a 100a supply, and other concerns - EICR opinions
[ElectriciansForums.net] 16mm SWA tails maybe 9 mtrs from isolator on a 100a supply, and other concerns - EICR opinions
[ElectriciansForums.net] 16mm SWA tails maybe 9 mtrs from isolator on a 100a supply, and other concerns - EICR opinions
 
You are assesong the job as per BS7671, nithing else so UKPN has no bearing on it.
I was under the impression for BS7671 you have to have fault protection for all cables, and overcurrent where necessary.
Overcurrent has been dealt with through assessement of max demand for the installation.
The fault protection for the tails is only by permission with UKPN, so if UKPN has no bearing, surely that means it would be unsatisfactory by default due to no valid fault protection? If they only allow 3m if they are happy for their fault protection to be used, then that's that?
 
I was under the impression for BS7671 you have to have fault protection for all cables, and overcurrent where necessary.
Overcurrent has been dealt with through assessement of max demand for the installation.
The fault protection for the tails is only by permission with UKPN, so if UKPN has no bearing, surely that means it would be unsatisfactory by default due to no valid fault protection? If they only allow 3m if they are happy for their fault protection to be used, then that's that?

I thought the same until I read through a load of posts.

IET Forums - EICR - https://www.------.org/forums/forum/messageview.cfm?catid=205&threadid=70233

"
Not BS7671 as such, but in the paperwork from a well know DNO..
If you want connection, you need ot do what they ask for.

4.6 Meter Tails
Standard 25mm2 copper double-insulated conductors (meter tails) from the meter to the cut-out shall be provided and installed by the appointed meter operator.
Standard 25mm2 copper double-insulated conductors shall be provided and installed by the customer from the consumer unit for connection by the meter operator into the outgoing (load side) of the meter.
BS 7671 Regulation 433.2.2 requires a maximum three metres distance between overload protection devices and their source, therefore the customer shall provide and install an intermediate switch fuse or isolating switch if the distance between the meter and consumer unit is greater than three metres.
The customer should seek professional electrical advice to determine the protection equipment that is appropriate for the customer given the impedance at the cut-out and the design of their installation as UK Power Networks is unable to advise on these aspects.
Meter tails shall not be installed or run inside the cavity wall of a building other than passing directly through the wall.
Tri-rated cables shall not be terminated onto UK Power Networks equipment.



quoted from page 6 of the
ENGINEERING DESIGN STANDARD EDS 08-0129
LV CUSTOMER SUPPLIES UP TO 100A SINGLE PHASE
"
 

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