Extending short wires in consumer unit?

sasolshares · 1 Jun 2004

I want to replace a fusebox with a MCB consumer unit, but the neutral wires in the fusebox are quite short. Is it permisable to extend them inside the consumer unit using connector blocks?

Big_Spark · 1 Jun 2004

Absolutely not.

If it is not possible to rewire those circuits, or not practical, then the only method acceptable is CRIMPED TERMINALS.

sasolshares · 1 Jun 2004

Thanks for that. Do you mean using pre-insulated butt crimp connectors?

ban-all-sheds · 1 Jun 2004

You can also use DIN rail mounted through terminals.

sasolshares · 1 Jun 2004

Hi guys,
Getting a bit confused here. The wires in question are not long enough to take to any sort of connector block on the din rail, so was intending to have loose in-line joints using connector strip to extend these wires by 2 or 3 inches to reach the consumer unit neutral strip. FWL_Engineer suggested crip terminals, but I assume we are talking about butt crimp connectors to make an end-to- end joint on each wire. As a matter of interest, why are the screw connections of a connector strip unacceptable?

crystal ball · 1 Jun 2004

I fail to see why connector strip is not acceptable to extend cores, there are JB's on the market using connector strip and virtually every accessory uses screw terminals, I have seen quite few crimp joints on solid cores fail and will never use them on solid core cable. It is not ideal to have floating joints though, and they should be secured to the base of the enclosure, difficult to do that with crimps.

ban-all-sheds · 1 Jun 2004

Glad to see the debate on the suitability of crimps on solid-core cables won't go away....

sasolshares said:
Hi guys,
Getting a bit confused here. The wires in question are not long enough to take to any sort of connector block on the din rail

What about putting something like this before the CU:

Position it so that the existing cables reach it comfortably, use DIN mounted terminal blocks:

and new lengths of cables through to the CU.

plugwash · 1 Jun 2004

no bas

din rail terminals are not shaped properly to be fitted into CU style din rail enclosures (which expect a device with a large protrusion in justthe right place to go through the panel

also that box is intended to be bolted to a 3 phase board and for the end cover plate of the 3 phase board to be moved onto it its not really suitable for any other fitment

if hard to replace cables only exit the CU in one direction then you could move the CU position a bit

securespark · 1 Jun 2004

Going to suggest something to make many take a sharp intake of breath.

What about mounting the CU in such a position that whichever group of cables is the lesser (ie those going up or those going down) can reach, and the others are extended via accessible jb's??

plugwash · 1 Jun 2004

another option along those lines

MK do a multi level kit for thier CUs
then put stuff leaving upwards on the top rail and stuff leaving downwards on the bottom rail

ban-all-sheds · 1 Jun 2004

plugwash said:
no bas

din rail terminals are not shaped properly to be fitted into CU style din rail enclosures (which expect a device with a large protrusion in justthe right place to go through the panel

also that box is intended to be bolted to a 3 phase board and for the end cover plate of the 3 phase board to be moved onto it its not really suitable for any other fitment

if hard to replace cables only exit the CU in one direction then you could move the CU position a bit

Well - on closer examination of the picture......
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You're quite right - it'd be useless.

So buy a length of DIN rail and put it in the adaptable box of your choice

Or maybe a row of these screwed to the wall?

They're rated at 60A, with 2 screws per conductor they should achieve a good contact, and with all but the largest cables you could probably get each one to run all the way through the terminal thus having 4 screws bearing down, they are enclosed, they have grips to lessen the chance of mechanical stresses on the connections, and they are accessible for inspection.

There is no logical reason for them to be unacceptable, but we all know about logic and wiring regs, don't we?

securespark · 2 Jun 2004

Still like to query Jim's connector versus crimp, especially on fracture-prone solid conductors.

Jim?

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Extending short wires in consumer unit?

Big_Spark

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