replacing consumer unit

[climberjim]

Dear all,

I wish to replace my old re-wireable fuse consumer unit. I have arranged for the electricity co. to come out and fit an isolator in a couple of weeks time.

I don't think the existing arrangement is 16th edition compliant. The company fuse and meter are in an outside cabinet mounted in the wall i.e. the meter etc are mounted on a board attached to the internal concrete block wall. The consumer unit is mounted indoors on other side of this wall, roughly a meter higher-up. Currently the meter-tails run up inside the cavity wall and the circuit wiring from the consumer unit goes up inside the cavity to the 1st floor.

As I understand it running cable in the cavity of an external cavity wall is no longer permitted (or just not recommended?). None of the tails/cables are inside any conduit.

Can I leave the existing arrangement as I'm not doing a complete re-wire?
I could probably run the meter tails inside some (fairly flexible) plastic pipe if that makes any difference. As I understand it the meter tails should be run straight through the wall (in a conduit) but I don't want meter tails running up the internal wall where they will be knocked and bashed by all and sundry or a consumer unit at shin level.

With regards to the existing circuit wiring I'm tempted to put a small cabinet (presumably there are specs. for fire protection?) on the (wall above on the) first floor for use as a large junction box, run new cables up the wall from the consumer unit to the cabinet and connect there to the existing wiring. (my reasoning being there's bound to be a cable that just too short and will simplify replacing any of the existing wiring if required)


Does anyone have any comments/suggestion?

I have access to copies of the wiring regs (and some other texts e.g. onsite guide) if it would be easier to point me towards the relevant sections.

Many Thanks

Jim Ingram

 

[breezer]

i personaly do not like the sound of I'm tempted to put a small cabinet for use as a large junction box,

junction boxes are not a good idea

 

[ban-all-sheds]

....junction boxes are not a good idea

What about things like these:

 

[climberjim]

Breezer,

i personaly do not like the sound of I'm tempted to put a small cabinet for use as a large junction box,

junction boxes are not a good idea

Is this an excuse for not answering the rest of the question or do you simply not know. I have looked for the information in various books e.g. Whitfield; electricians guide to 16th ed., on-site guide, Brian Scaddam; Electric wiring: Domestic etc but cannot find any information on this particular issue. Maybe this cavity wall business is actually to do with building regs?

Anyway with regards to having additional junction box what's the problem?

a) I can't see that its any different to joining cables with a socket or ceiling rose. In fact if anything since your not having to push cables back into the pattress they're probably less likely to come loose.
b) Housed in a small cabinet the boxes/ chockblock or BAS suggestion would be 1) accessible for testing 2) Free from damage from mechanical impacts.



Thanks

Jim

 

[il78]

I agree with breezer with the idea a plastic adaptable box in your hallway landing may look a bit ugly but your left with limited options, other being moving your fuse-board.......but you live there, not me....

Cavity wall thing...I dunno....I've never heard anything apart from on here......

 

[climberjim]

I agree with breezer with the idea a plastic adaptable box in your hallway landing may look a bit ugly but your left with limited options, other being moving your fuse-board.......but you live there, not me....

I'm not sure breezer said that or am I missing a post?. Anyway are you saying I should (must?) house the consumer unit in a box? I was just going to screw the new one to the wall where the existing one is.

I did think about moving it further up the wall i.e. more out of the way. (I haven't checked but am I right in thinking that I could have slightly longer meter tails (but less than 3 meters) without having to put in an additional fuse&isolator or rate tails for maximum supply current (as opposed to my demand)?). To be honest though I'm not really that bothered about its location although it would give me a bit of spare cable length for wiring the old wiring into the new CU in.

Cavity wall thing...I dunno....I've never heard anything apart from on here......

I've seen references to it on the net but I can't remember where now. I think I'll probably just leave the cables as they are (I can think of any sensible alternative for the tails anyhow).

Thanks

Jim[/quote]

 

[securespark]

My local EB does not like tails (cables from meter to consumer unit) longer than 2 metres.

 

[breezer]

all i said was i do not like the idea of a box some where on a wall full of junction boxes.

regs say must be crimps (lets not go in to that one again)

it will look awfull (but i too don't live there)

If it still has rewireable fuses how about a complete re wire (not saying it should just it may be time)

and also climberjim, you said "Does anyone have any comments/suggestion? "

So dont start whinging when you do not like my opinion, after all it was you who asked for "any comments/suggestion? "

they were mine

 

[climberjim]

all i said was i do not like the idea of a box some where on a wall full of junction boxes.

regs say must be crimps (lets not go in to that one again)

On the subject of crimps whats the best way of using them? Stagger each connection so they can't touch and wrap in tape. Presumably a single union is better than two spades or rings for joining two conductors.

it will look awfull (but i too don't live there)

It would be in the back of a built in wardrobe so not an issue.

If it still has rewireable fuses how about a complete re wire (not saying it should just it may be time)

It may come to this. But I intend to extend the kitchen and put in a new ring and so would rather leave it for now. Currently the whole house is one ring. I've arranged to borrow a Megger (and hopefully a low ohm meter) for when the new CU goes in so I'll check the wiring out then and come up with a plan. Perhaps ideally I should sort the wiring out first and then replace the CU but it suits me to do it this way round. In any case I hate doing anything with the existing unit as its cramped and there's 1/2 an inch of exposed live meter tail poking out of the connector.

and also climberjim, you said "Does anyone have any comments/suggestion? "

So dont start whinging when you do not like my opinion, after all it was you who asked for "any comments/suggestion? "

they were mine

Fair enough. But it might have been more helpful if you'd elaborated a little more as to why. Anyway do you know anything about this cables in cavity wall business or does it just exist in my imagination?

Thanks

Jim

[/quote]

 

[amtodd]

Jim, between the regulars on this site many hours have been devoted to crimps, but it still looks like you are likely to kill yourself. You will need butt crimps. This is not something which Yankee-Sparkey will use for his nocturnal activities, but what you need to joint your cables. Spade/ ring terminals etc may be suitable for cars, speaker connections and inside exquipment, but if you use them for your wiring, I suggest a new forum may be required for DIY coffins.

You can find butt crimps at Screwfix, RS and many other suppliers. There are different sizes for different cable diameters.

• Do use the correct size as you will not get a good joint otherwise.
  Do use a proper tool such as these and not the type sold with kits intended for cars (Even B&Q sell reasonable ones for £20 inc vat these days).
  Do not use them to joint more cables than they were designed for. (butt connections designed for two cores to be joined).
  Do not use them on ELV kit as they do not take to temperature as well as the silicon cable many ELV lamps have.
  Do stagger the joints where possible.
  Do strip off the minimum amount of insulation possible so that there is a firm joint, but there is no bare copper showing.
  Do ensure your joints are properly contained inside conduit, trunking or some kind of suitable box.

As for cables in cavity walls, there are different recommendations from different organisations regarding the possible injection of foam insulation into the cavity. Ignoring that arguement completely, there are additional reasons why cables in cavities are not my preferred way of installing: any cable needs to be physically supported at regular intervals to prevent damage under its own weight. In a cavity, there is no support to the cable other than at the top of the run. Secured in this manner, a between floors cable under heavy current (and therefor warm), could result in the cores pulling through the insulation, and now we are back to MDF coffins again.

 

[ChrisRogers]

if you want to put more than 2 wires in a crimp use 6.00mmm crimps