Adaptable Box?

[Greenie9657]

Hi All

People who have seen my previous posts will know im having to sort out the wiring in every room as i move through my new (1930s) house as there arent enough sockets, spurs from spurs etc etc....

Anyway, as im going underneath my hall way i thought i might as well sort out wiring under there for when i get my new CU fitted later in the year.
Im going to put in cable from the CU to 2 adaptable boxes:-
.... 1 on the drive wall for the garage CU which im kind of happy with the dimensions and ill be using 6mm2 from CU then 6mm SWA from adaptable box 1 to the garage. Suggestions are welcome;
....The other one is just going to be 2.5mm2 from the CU to the box then 2.5mm2 SWA to 2 maybe 3 front garden lights. What size adaptable box would take the 2.5mm2?

Thanks for you time..

 

[Greenie9657]

I might be too cautious here thinking i need access to the joints but if i was to use crimps and heat shrink am i right in saying i wouldnt need that access and i could just bury it under the hall floor? The floor is all floor boards.

 

[ericmark]

Being pedantic I know but for domestic the distribution unit should be type tested. Although we all know the adaptable box will do the job if inspected by a "jobs worth" he could fail it.

I am sure some where buried in the wall in my daughters house there is an adaptable box. The wiring in the consumer unit does not seem to match what is found in the rest of the house. I would guess done when garage converted to a room.

Having had to contend with this I would advise it does really need to be accessible. If accessible then want it to look right so I would consider using a mini consumer unit rather than just a joint box.

With DIN rail in a joint box the proper terminals can be fitted complete with link bars where required.

these are also available as maintenance free but I would say either a box which you can access or use a proper shrink sleeve joint for each cable.

I would be interested in other peoples opinion as to using non type tested stuff in a domestic premises. I have built many control panels and distribution boards but never fitted any in a domestic premises. I have raised before the problem with old central heating installs where the electrician has used a simple back box and cover instead of the proper unit where all the terminals are set up for the job. The main problem is multi earth wires. At least with DIN rail

the earth wires are interconnected. But never seen these with domestic.

 

[Greenie9657]

Thanks for the reply mate.

The adaptable boxes would be easily accessable as one would be on the side of my porch (not seen from the road) and the other would be on the wall just above my drive (for the garage). But i could splice the new cables in if this is allowed then i wouldnt need to boxes at all.

 

[Greenie9657]

As im in the process of digging up the drive and building a porch ive found an old steel/galvanised conduit running pretty much the entire lengh of the driveway, and luck would have it that it ends underneath where my garage/shed is. Its still got a cable in there that looks like its been there since the house was build. Anyway, rather that lay SWA if i could manipulate/join this conduit to run from underneath my hall, all the way down the drive to the garage could i use normal 6mm2 twin and earth inside the conduit or is it worth just getting rid of it and laying swa?the cable has pulled out freely so its clear all the way through.

thanks

 

[JohnW2]

... ive found an old steel/galvanised conduit running pretty much the entire lengh of the driveway, ... the cable has pulled out freely so its clear all the way through.

Did you pull anything (like a draw cord) through the conduit when you pulled the cable out?

Kind Regards, John

 

[bernardgreen]

could i use normal 6mm2 twin and earth inside the conduit or is it worth just getting rid of it and laying swa?the cable has pulled out freely so its clear all the way through.

Was the cable you pulled out completely dry ? Or would the "normal twin and earth" be laying in water in the duct. ? Not good.

And how mechanically robust is the iron along the entire length ?

damage to the twin and earth as you pull it in could result in the live conductor being exposed with the subsequent risk of the metal duct becoming live.

In short, by all means use the duct but for SWA Damage to it's outer sheath will expose only the earthed armouring so not be a serious hazard, at least not until the armour rusts away.

 

[OwainDIYer]

I don't think there's anything wrong with joints in adaptable boxes. It is, after all, largely what adaptable boxes are for - apart from breaking the general principle in conduit wiring that all joints should be at accessories and adaptable boxes should only be for carrying wires between conduits.

However it is neater if a terminal strip is fixed to the box instead of having individual terminals dangling about on the ends of cables.

 

[Greenie9657]

... ive found an old steel/galvanised conduit running pretty much the entire lengh of the driveway, ... the cable has pulled out freely so its clear all the way through.

Did you pull anything (like a draw cord) through the conduit when you pulled the cable out?

Kind Regards, John

Hi John

Yeah, its force of habit (and learning from my own mistakes) even when ive finished putting in the wires i always leave 1 piece of cord in just incase i need to pull anything else through in the future.

 

[Greenie9657]

Hi Bernard.

I cant get the conduit out of the ground and i cant check underneath the garage but the section i can see seems very intact and the cable came out of it without any snags. i could always either con check the conduit to each of the conductors or i could do insulation resistance checks from the twin and earth to the conduit just to make sure nothing is touching or breaking down. (obviously with both end disconnected)

 

[bernardgreen]

Having myself used twin and earth in a duct I laid myself I would NOT recommend it. When I removed it after a few years the cable was obviously discoloured and did not feel right. Immersion in water had affected it. The duct should have been dry, the ends were 18 inches above ground level, but had become water filled during a flood. Other ducts not affected by the flood were also wet due to condensation over the years.

 

[JohnW2]

Hi John, Yeah, its force of habit (and learning from my own mistakes) even when ive finished putting in the wires i always leave 1 piece of cord in just incase i need to pull anything else through in the future.

Great. Just checking

Kind Regards, John

 

[ban-all-sheds]

I don't think there's anything wrong with joints in adaptable boxes. It is, after all, largely what adaptable boxes are for - apart from breaking the general principle in conduit wiring that all joints should be at accessories and adaptable boxes should only be for carrying wires between conduits.

So buy ones sold with integral terminal blocks - they must be junction boxes.

OOI - how have you determined that "general principle"?

 

[JohnW2]

Was the cable you pulled out completely dry ? Or would the "normal twin and earth" be laying in water in the duct. ? Not good.

Having myself used twin and earth in a duct I laid myself I would NOT recommend it. When I removed it after a few years the cable was obviously discoloured and did not feel right. Immersion in water had affected it.

'Affected', no doubt - but in a significantly deleterious manner?

I'm now nearly 4 years into my long-term experiment of leaving T+E submerged in a solution of salt and various other electrolytes. At the last count, its IR was still fine (even at 1000V). Also, I've recently removed (and replaced with SWA, mainly 'just for the sake of it') a long length of T+E which had been in an (often partially water-filled) duct for at least 26 years (my period of occupation), probably a fair bit more. Again, it was still 'working fine' and IR at 1000V was still OK.

Probably the greatest environmental hazard to PVC cables is that various factors (heat, UV, polystyrene, other chemicals) can cause the PVC insulation to become brittle, hence at risk of cracking, or even crumbling, when flexed. However, even if the PVC did become brittle, flexing is not going to happen with a cable in conduit or ducting (or securely clipped to a surface).

I therefore am not too concerned about PVC cable remaining wet. My greatest concern, which you have mentioned, would relate to the possible damage to PVC cable which could result from pulling it through potentially rusty conduit. However, given that condensation (hence potential rust) gets everywhere, that's probably an ever-present risk whenever cables are pulled through 'old conduit', even indoors. One should certainly IR test any cable after it's been pulled through conduit/ducts - although a satisfactory IR obvioulsy does not preclude significant cable damage. I would personally use SWA, 'to be safe', but I think it's a fairly close call.

Kind Regards, John

 

[ericmark]

I have found twin & earth seems to snag when drawn through conduit. I would be temped to use a flex as the smoother surface does not snag as much.

I have in the past used washing up liquid until I was told how it contained benzene and could explode. Now I use Yellow77 designed for the job. Also in the past used soap and tallow not sure if they will explode but not inclined to do the tests.