Consumer unit to be moved away from service head

[Midwest]

The old school rule of thumb is to exclude the highest rated circuit breaker, add up up the rest of the circuit breakers, times this figure by 0.4 and add this figure to the rating of the highest circuit breaker you excluded.

That sounds just as ridiculous as Appendix A in the OSG

 

[Bellendian]

I've not come across a 'standard' house yet that can't live on 16mm and 60A, even big ones. Max demand calcs are a pita, you can talk yourself into all sorts of absurd figures, but the reality is that these scenarios never arise, and on the off chance that they do, the dno aren't daft enough to let your error damage their network beyond the fuse in the cutout.

 

[buzzlightyear]

Yes main fuse rating is 100A, thank you.

And i know it wasnt a dig! I work for a housing association and havent done any maximum demand calculations since my college days

http://www.napitonline.com/downloads/CP 4 07 P 10-11 16th Diversity.pdf

 

[Pete999]

no worries pete, i served a 4 year apprenticeship and have been qualified for 2 years and have my 17th edition (18th booked in), the 2357 NVQ and just recently passed the Inspection and testing 2391.

Thanks Chris

 

[telectrix]

Yes i only made this the other day i am yet to fill in all the details, will get round to it soon.
Yeah the supervisors do all the drawings and calculations so the rust appears to have set in haha! No offence taken.
That was my thought too im almost certain it will be too large for the MET i may have to figure something out for that.

you can fit a reducing lug.

 

[Octopus]

at the foot of the NAPIT document linked above

"Conclusion Other methods of determining the maximum demand can be used with the values selected being the responsibility of the installation designer or a suitably qualified electrical engineer."

Yup - like the one outlined by the IET is completely irrelevant these days with fuseboards typically having more breakers ......

 

[Chris]

Hi Everyone, i have decided to install a 25mm 3 core SWA from an 80a FCU like the one shown here
Wylex Domestic Switch Fuse 80A - https://www.toolstation.com/shop/Electrical/d190/Wylex+Consumer+Units/sd2615/Wylex+Domestic+Switch+Fuse/p51068

However the earth terminal on the FCU can take a maximum of 16mm. 16mm is fine for the main earth CSA but the cores are all 25mm for the L+N tails..

Can i use a 2 core 25mm SWA and use the cable sheath for the sub main from FCU?

If only there was a 2x25mm/1x16mm SWA!

Anyone have any suggestions?

 

[Spoon]

Anyone have any suggestions?

Maybe something like this.

 

[Bellendian]

Why not use ring crimps on the 25mm and fix both incoming and outgoing earths to the SWA banjo bolt. Could even run a 16mm fly lead from earth terminal to banjo if you were concerned about earth to switch fuse casing.

 

[Chris]

Thanks lads, big help!

 

[Octopus]

3 core 16mm would be the best way forward if you haven't bought the cable ..........

remember the switch fuse is 80A

 

[Chris]

I think that may be the easiest way to go murdoch, i was hoping to put 25mm in as that is what everybody seems to recommend now a days but it might be a bit too much messing around

 

[Octopus]

Check the ccc for 16 mm swa ...

 

[Chris]

Brill, 16mm it is. Thanks murdoch