New SWA Supply from DNO Isolator to Upper Flat

[Right Spark]

Hi guys first post here and looking for the best solution to this problem.

4 in a block flats with separate front doors.

External meter boxes for each flat.

The upstairs flats 25mm tails are run in a pipe box in the downstairs neighbours flat up into the upstairs flat and across the attic to their consumer unit.

Downstairs Neighbour has found the Upstairs neighbours tails In his property and has tapped into them (free electric, disconnected now).

I’ve been brought in to make sure this can’t happen again so my plan is to run a 25mm 3 core SWA externally then bring it into the upstairs property high level therefore bypassing the downstairs altogether and making it tamper proof.

My issue Is that I cant make up my mind of the best way to supply the SWA from the DNO’s 100a plastic isolator, which I obviously can’t connect into direct without an intermediary. It’s the usual sized electric/gas semi recessed external meter box containing the cable head, smart meter and isolator switch so there’s not a huge amount of room to add any more switchgear into.

My plan was to fit a separate meter box next to the original one, install a 100a SP+N Metal Switch Fuse ( https://www.cef.co.uk/catalogue/products/4390934-100a-sp-n-switch-fuse-with-100a-hrc-fuse ) and terminate the SWA into that with the DNO isolator feeding it. But I need to then figure out some way of getting the double insulated tales from the Isolator in the original meter box into my new one without it looking like a pigs ear, which I’m struggling to come up with a decent solution. Possibly copex?

In the property I plan to swap out the plastic consumer unit for an amendment 3 metal one and terminate straight into that.

Can anyone suggest anything better? As I say getting the supply into my new box via the isolator is the bit that’s puzzling me the most...

I’m open to any suggestions.

 

[Murdoch]

Do you have the freeholders permission to run the cable externally etc?

 

[Right Spark]

Do you have the freeholders permission to run the cable externally etc?

Yes this has all been discussed.

 

[Murdoch]

Yes this has all been discussed.

Good man - not everybody does this .......

 

[Sharpend]

This semi recessed box is this in the outer skin of a brick wall? 

 

[Right Spark]

This semi recessed box is this in the outer skin of a brick wall? 

Yes, It’s had it’s broken door replaced with a metal overclad replacement similar to this.

https://ritherdon.myshopify.com/products/r18e-replacement-door-and-frame

 

[Phoenix]

I think what is being got as, was just fish the tails between the two recessed meter boxes in the void...

And not helpful, but AFAIK this is the reason the DNOs often used MICC for the 'soft latteral' main between the head and the mter (so on the unmetered side) in flats etc, it makes it very difficult for someone to tap into!

 

[Right Spark]

I think what is being got as, was just fish the tails between the two recessed meter boxes in the void...

And not helpful, but AFAIK this is the reason the DNOs often used MICC for the 'soft latteral' main between the head and the mter (so on the unmetered side) in flats etc, it makes it very difficult for someone to tap into!

I don’t think fishing between boxes via the cavity will be possible in this instance. 

 

[Sharpend]

Why? 

 

[Right Spark]

Why? 

My remit is to keep all of the wiring out of the reach of the downstairs neighbour. Although unlikely, if the tails run between the cavity of their property there is the possibility of access to them, regardless of the slimness of the chances. 
My spec is to run all cable where there is no possibility of unseen tampering.

 

[Sharpend]

Get an engineering firm to bend you a piece of steel tube to fit then put tails inside. 
think the neighbour might be extremely desperate for electricity if they’d take the wall down from inside to get too the tails? 

 

[Right Spark]

Get an engineering firm to bend you a piece of steel tube to fit then put tails inside. 
think the neighbour might be extremely desperate for electricity if they’d take the wall down from inside to get too the tails? 

Hi mate, I appreciate your input but I didn’t come on here to argue semantics. To keep it civil I’ll just say politely that I know what’s expected in this job and also the history, which you don’t. I’ve stated a few times now that this isn’t an option and would like to move on. Thanks

 

[Sharpend]

So you have been brought in to sort a problem that is impossible to sort without bringing the tails out through the door of the existing box as any other route would be within the cavity? 
the supply cable comes into box externally or through cavity? 
can you exit the box externally at the bottom or side into a metal IP rated box to mount switch fuse in then up wall? 
 

is there room to mount a small kmf to feed new swa to flat in meter box? 

 

[SPECIAL LOCATION]

I didn’t come on here to argue semantics. To keep it civil I’ll just say politely that I know what’s expected in this job and also the history, which you don’t. I’ve stated a few times now that this isn’t an option and would like to move on. Thanks

Don't think anyone is arguing semantics...? :C

More like a perfectly reasonable observation IMHO...

And I can't see where you have stated "a few times" what your options are.. or are not...

To keep things civil I would suggest you climb a few rungs down you step ladder and  be a bit more understanding of people who are trying to get an angle on what you are asking for....

and what possible solutions there may be to your problem..

If you have chosen to withhold certain critical elements of detail relating to this job then that's your problem..

Not others who are trying to help..

headbang  

 

[Right Spark]

In my experience cavities are not for installing any sort of wiring in?

 

[Right Spark]

guidance from the Electricity Safety Council says "installing such cables in this way (external cavity walls) is generally an undesirable practice" 

Reasons: 

Obstructions in a cavity wall, such create a risk of unseen damage during installation.

Long unsupported vertical drops may place undue strain on the 
conductors, leading to damage - Not applicable really in this case, but still.

Polystyrene used for insulation, if it come into contact with thermoplastic (pvc) cable sheathing, plasticiser can migrate from the thermoplastic to the polystyrene 

Thermal insulation in the cavity may cause cable not to be able to carry the load current without overheating due to their current-carrying capacity being reduced.

Presence of flora and fauna - unforeseen external influences.



Building Regulations 2000  and NHBC Standards state that no cables other than electricity meter tails are to be located in the cavity of an external wall.

sorry, I’ve  never in my 25 year career wired anything in The cavity of a building and I’m not about to start now.
 

 

[Sharpend]

Meter tails are what we are talking about between two cabinets a total of probably 30cms of cable to which the insulation can and will be removed when the new box is installed. The polystyrene balls will cascade out once the brickwork is opened up, it is usually if builder is conscientious enough replaced with the fibre insulation bats which being stiffer means you can leave a small channel for the tails. 
 

to say no cables are in cavities is utter impossible rhetoric otherwise there would be no outside lights for one and how many consumer units are installed directly behind the utility meter box to minimise meter tails in cavity. They are usually within the 3m rule so that’s 3m of cable in a wall cavity?  
So whilst the council say its undesirable practice I would say with a logical head or old fashion common sense  that they are implying that general wiring within cavities should be avoided where possible ie in conservatories or extensions etc. Who would wire a ring circuit or lighting circuit in a cavity in normal practice? 

or do you not install any cables in a cavity? 

 

[Right Spark]

Meter tails are what we are talking about between two cabinets a total of probably 30cms of cable to which the insulation can and will be removed when the new box is installed. The polystyrene balls will cascade out once the brickwork is opened up, it is usually if builder is conscientious enough replaced with the fibre insulation bats which being stiffer means you can leave a small channel for the tails. 
 

to say no cables are in cavities is utter impossible rhetoric otherwise there would be no outside lights for one and how many consumer units are installed directly behind the utility meter box to minimise meter tails in cavity. They are usually within the 3m rule so that’s 3m of cable in a wall cavity?  
So whilst the council say its undesirable practice I would say with a logical head or old fashion common sense  that they are implying that general wiring within cavities should be avoided where possible ie in conservatories or extensions etc. Who would wire a ring circuit or lighting circuit in a cavity in normal practice? 

or do you not install any cables in a cavity? 

yeah all this is true, totally agree.

another thought, can I terminate the gland into the top of the metal GRP enclosure and take my cables to the iso switch that way?

i know there’s the whole thing about cables are required to be double insulated in a mains area if run without protection which might rule this method out?

sorry if I came across as difficult last night, there’s a few jobs that’s got me stressed, I’m genuinely a nice guy and I’m pretty knowledgeable with the regs and was hoping to partake in these forums and help out with advice where I can.

 

[Sharpend]

From my experience on new builds years ago the double insulated rule in the meter box was disregarded as we use to put swa into the isolator via an earthing gland. Apparently this was agreed by those that write the rules. :C  

Is it a metal box or GRP (glass reinforced plastic ) ?  

 

[Right Spark]

From my experience on new builds years ago the double insulated rule in the meter box was disregarded as we use to put swa into the isolator via an earthing gland. Apparently this was agreed by those that write the rules. :C  

Is it a metal box or GRP (glass reinforced plastic ) ?  

the Original box is the standard gas/electric meter GRP but has a Ritherdon style replacement door and frame over it now which is metal.

thanks that’s good info to have about the relaxing of the DI rule.

Yes sorry, mixing my terminology up. I’m that used to calling meter boxes GRP boxes that it’s become a universal term for them. I see why you’re confused lol!