4 sq mm Radial - Never again!

[Piratepete]

Had to rewire part of a house (inc kitchen) and the layout suggested that the best solution was a 32Amp 4mm radial cct for the power (sockets etc). I hadn't done one for years!

No problem doing 1st fix - 4mm is nice and flexible.

2nd fix. Using MK Logic White could get 2 x 4mm into the terminals, could just about get an extra 2.5mm in where there was a single spur (though particularly difficult on the back of a switched fused spur), but no way could I get 3 x 4mm in where I was branching off to 2 or more sockets.
Also had problems stripping 4mm cores cleanly - insulation much softer than on 2.5mm.

Anyone else had problems using 4mm. Funny thing is, my local supplier says he sells loads of 4mm!

Cheers

Pete

 

[ipf]

4mm better for radials, but never branch off resulting in 3 at a point.

 

[bugsy]

if its a new install why the spurs

 

[Deleted member 9648]

Poor design mate if you are wiring a new radial and ending up with 3x4mm's at a socket.

 

[highspark]

Never ever see the point in 4mm radials. If it exceed 50m squared throw rings i4mm radials are crap for this reason I'm all for radials but only 2.5m 20a!

 

[Piratepete]

if its a new install why the spurs

Why not? I'm always keen to save on cable! It's allowed!

 

[Piratepete]

Poor design mate if you are wiring a new radial and ending up with 3x4mm's at a socket.

Not my original plan - change of mind by customer - but what's wrong with spurs? It's allowed, there's a lovely diagram in the regs Appendix 15 in the Red book, and I save on cable.

 

[highspark]

Why not? I'm always keen to save on cable! It's allowed!

You could have saved cable if you ran 2.5mm rings! Or 20a radials depending on size of install

 

[Piratepete]

You could have saved cable if you ran 2.5mm rings! Or 20a radials depending on size of install

Kitchen and Utility cct so 32 Amp. long run to CU and because of ceiling construction (steel beams and open voids to roof) no way to continue a ring all the way around. As I said at the beginning - radial looked the best solution.

Back to original question - is it just MK that has terminal holes really only designed for 2.5mm?

 

[Engineer54]

All power accessories these days allow a max of 10mm!! Around 5 or 6 years ago it was 12mm!! Makes a hell of a difference when your wiring in 4mm cables!! lol!!

 

[One_of_them]

regs Appendix 15 in the Red book

Green book now

 

[Piratepete]

Green book now

Someone had to notice! Couldn't be arsed to fetch it from the van! By the way - The new Site Guide is full of lots of new interesting subjects - I like it!

Cheers

Pete

 

[GLENNSPARK]

wanna watch your Zs n all with 4mm....only a 1.5mm CPC in it.....so you have a 32A radial which for MCBs to BS60898 will be 1.16 ohms.....not much especially on longer runs....

 

[Piratepete]

All power accessories these days allow a max of 10mm!! Around 5 or 6 years ago it was 12mm!! Makes a hell of a difference when your wiring in 4mm cables!! lol!!

So 4 + 4 + 4 = 10 now! Hmm.

At this point should I also make a rude comment about lighting accessories which won't take 3 x 1.5mm!
Thank goodness the 4mm supp. bonding wire has all but disappeared from the scene! When I did my BS7671 course 10 years ago, I did suggest removing some strands off the 4mm wire to make it fit in the earth terminal as it's only required to be 2.5mm inside the accessory (mechanically protected)! I can't print the lecturer's reply! :90:

Cheers

 

[Engineer54]

So 4 + 4 + 4 = 10 now! Hmm.

At this point should I also make a rude comment about lighting accessories which won't take 3 x 1.5mm!
Thank goodness the 4mm supp. bonding wire has all but disappeared from the scene! When I did my BS7671 course 10 years ago, I did suggest removing some strands off the 4mm wire to make it fit in the earth terminal as it's only required to be 2.5mm inside the accessory (mechanically protected)! I can't print the lecturer's reply! :90:

Cheers

Did i say that?? .....Nope, What i said WAS, that previously accessories COULD take 3 X 4mm, being 12mm, but they WON'T now!! Is that plain enough?? lol!!!

 

[Piratepete]

Did i say that?? .....Nope, What i said WAS, that previously accessories COULD take 3 X 4mm, being 12mm, but they WON'T now!! Is that plain enough?? lol!!!

Understood the first time!:rolleyes4: Whose clever idea was it to reduce the size?

I'm off to bed! Another busy day tomorrow, full of fun, no doubt! Nite

 

[Engineer54]

Understood the first time!:rolleyes4: Whose clever idea was it to reduce the size?

I'm off to bed! Another busy day tomorrow, full of fun, no doubt! Nite

Pass, ....haven't got a clue who or why!! lol!!!