0.5mm T&E cable now available.

[Dustydazzler]

Also a lot of ham fisted DiYers and some ham fisted sparks struggle to make off 1mm connections without mashing the ---- out the copper conductor. So getting them to make of 0.5mm cable would be near impossible for them...

I do like the idea of 0.5mm cable for domestic lighting but the cost saved on cable over a basic rewire compared to 1mm would probably only be £10 , so hardly worth it in the grand scheme

 

[John-SJW]

+1 to them for an April fools idea that actually makes for interesting discussion.

One problem with a very small cable is its lack of mechanical strength. Although @John-SJW is quite right that it could be installed in an electrically safe manner, it might be too flimsy without additional mechanical protection, at which point the advantage of economy is lost.

The reduction in overall size is moot; it might not be possible to reduce the radial thickness of the insulation and sheath, for both mechanical and electrical strength reasons, in which case the overall dimensions would be only slightly smaller than that of 1.0. The volume of plastic dominates in the small sizes under consideration, unlike say 70mmsq where the copper dominates over the plastic.

CH control wiring on retros is done using flex.

A two bedroomed flat with a 2A RCBO or MCB using 0.5mm, as been mentioned, can do the lighting for sure. 0.5mm has a maximum current load of about 3A. If there was 50 5w LED lights in the flat, it would be highly unlikely we know, it would be 250 watts, which is about 1 amp. Totally safe.

The thinner cables would be a dream to wire up inside single light switches with Wagos inside for the switched live, and easy to run being so thin. A 50m reel of three core 0.5mm cable with an insulated CPC is about £16.50. A 50m reel of 1.00mm T&E is about £22 plus earth sleeving. Using ferrules obviously would be a more professional job.

Nothing says in the regs you cannot use flex for house wiring. In a 3 bedroom house, one lighting circuit with a 2A RCBO or MCB in 0.5mm for downstairs with the same upstairs. Very safe.

The only problem is it may encourage cowboy work. If that is a problem. Also electricians will perceive it deskills their job.

 

[nicebutdim]

CH control wiring on retros is done using flex.

That sort of makes Lucian's point about the ratio of plastics to copper and flex has an even greater CSA than T&E. While I enjoy the theraputic qualities of crimping ferrules on flex, it adds considerably to installation time.

 

[John-SJW]

One point raised. I prefer having a lighting junction in the light switch backbox rather than at the ceiling rose. It is easier to fit and fault find. Using T&E and a Wago in the light switch backbox made matters tight in there. 0.5mm and Wago in the backbox, makes it all so much easier.

Just thinking of positives of using 0.5mm over 1.00mm or 1.5mm T&E.

 

[John-SJW]

That sort of makes Lucian's point about the ratio of plastics to copper and flex has an even greater CSA than T&E. While I enjoy the theraputic qualities of crimping ferrules on flex, it adds considerably to installation time.

But the conductors are thinner when working inside backboxes and no earth sleeve needed. The flexible CPC conductor is ideal for connecting to metal backbox terminals. Pulling either of them will be similar. Then 0.5mm is cheaper.

An April Fool's joke sparked some positive thought.

 

[DPG]

One point raised. I prefer having a lighting junction in the light switch backbox rather than at the ceiling rose. It is easier to fit and fault find. Using T&E and a Wago in the light switch backbox made matters tight in there. 0.5mm and Wago in the backbox, makes it all so much easier.

Just thinking of positives of using 0.5mm over 1.00mm or 1.5mm T&E.

I think most people have moved on from 3 plating at the rose now to be honest. Light fitting design and smart switches drove that.

 

[nicebutdim]

One point raised. I prefer having a lighting junction in the light switch backbox rather than at the ceiling rose. It is easier to fit and fault find. Using T&E and a Wago in the light switch backbox made matters tight in there. 0.5mm and Wago in the backbox, makes it all so much easier.

Just thinking of positives of using 0.5mm over 1.00mm or 1.5mm T&E.

But the conductors are thinner when working inside backboxes and no earth sleeve needed. The flexible CPC conductor is ideal for connecting to metal backbox terminals. Pulling either of them will be similar. Then 0.5mm is cheaper.

An April Fool's joke sparked some positive thought.

Comparing like with like, there's no benefit to flex in terms of size, but obviously there would be where conductor CSA is reduced. The downside to fine flex within back boxes is a greater likelihood of damage - from both DIY and 'professional' workmanship alike.

 

[pc1966]

I have seen a bathroom light fed with 0.5mm flex (stuff like pendant lights, etc) from a FCU outside of the small room. Now had they only changed the 13A fuse for 3A...

 

[HappyHippyDad]

So, can we start using this 0.5mm then?

 

[HappyHippyDad]

So, can we start using this 0.5mm then?

Changed my mind.
Can't pluck up the courage to pretend I'm that silly.
Close though

 

[John-SJW]

So, can we start using this 0.5mm then?

Entirely up to you. Nothing says you cannot. Before 1.00 mm T&E I am sure many viewed having that as they are doing now with 0.5mm. What! Such skinny cable!

Although when using 1.00mm cable fitting a 2A MCB must tighten up the safety margin. If you have a light switch switching a 5A round pin light outlet, with side lamps with 0.5mm flex, using a 6A MCB does not fully protect the 0.5mm flex. A 2A MCB will cover all scenarios.

6A MCB for lighting now is far too high. Before anyone comes in, I know it does fully protect the 1.00 T&E cable at with a 6A MCB.

 

[pc1966]

Entirely up to you. Nothing says you cannot. Before 1.00 mm T&E I am sure many viewed having that as they are doing now with 0.5mm. What! Such skinny cable!

Not quite, the regs still say 1mm minimum for copper fixed wiring (16mm for aluminium should you ever have the misfortune to work with it).

EDIT: Don't have new one, but 524.1 for Table 52.3 has details. Seems for flexible cables you can use 0.75mm, but the '*' note says for multicore bundles of 7 or more!

6A MCB for lighting now is far too high. Before anyone comes in, I know it does fully protect the 1.00 T&E cable at with a 6A MCB.

I agree here, these days it should be 3A or less for light circuits. That would also deal with the stupidity of extractor fans!

Some brands offer MCBs below 6A, with 4, 3, 2, 1 and 0.5 in some cases (usually only C/D curve), but I have not seen a RCBO below 6A yet.

 

[John-SJW]

My point was that when 1.00 T&E was not available, many would be saying you can't introduce that bootlace when it was mooted 1.00mm T&E maybe coming.

I think I saw online a 2A//3A RCBO. Not cheap. Yes, 6A lighting MCBs and RCBOs are too high a value these days.

 

[pc1966]

My point was that when 1.00 T&E was not available, many would be saying you can't introduce that bootlace when it was mooted 1.00mm T&E maybe coming.

I think I saw online a 2A//3A RCBO. Not cheap. Yes, 6A lighting MCBs and RCBOs are too high a value these days.

I just tried a search and yes, some are available but not mainstream CU options. For example:

RCBOs | RCBO | Residential Circuit Breakers | RS

Shop our range of RCBOs to ensure your electrical circuits are running safely. Browse our latest RCBO Offers from leading brands. Free Next Day Delivery.

uk.rs-online.com

Cheapest is £63 but is 300mA trip! Suitable final circuit 30mA ones there start at £107 plus VAT.

Or this at £110 plus VAT:

https://www.bpx.co.uk/store/product/410997

If I had a request for mainstream CU it would be a 3A C-curve RCBO, that would have same switch-on limit (more or less) as current 6A B-curve MCB/RCBO and for dumbass extractor fan manufacturers.

 

[loz2754]

when 1.00 T&E was not available

When was that? In the early 1800s?

 

[John-SJW]

When was that? In the early 1800s?

You are too young.

 

[DPG]

When did 1mm T&E come in then?

 

[John-SJW]

It may have been available on order, but it was not sold in the mainstream dealers for sure. I was not aware of it. I came across it as a general stock item about 10-12 years ago when LEDs took off like a rocket.

I recall about 7 years ago a developer fitting 1.00mm T&E on the two lighting circuits in the houses. Shock, horror, bootlace! They used 6A MCBs rather than 3A, which was an oversight. 6A MCBs do protect the house cables, but 2A or 3A will protect 0.5mm flex to table lamps. The developer fitted a light switch in the living and dining rooms switching a few 5A round pin lighting sockets at skirting height for table lamps. Switching on-off the table lamps from one switch was selling feature. Memory is hazy but I think they fitted two-way switching in main bedroom to a bedside table lamp can be switched from the bed or doorway. Theoretically the 5A plug/socket is not protected using a 6A MCB. I assumed they used the cheaper 1.00mm T&E to offset the costs of the 5A lighting sockets.

The rule of thumb was that 1.5mm T&E was for lighting with no one ever thinking of doing anything else.

 

[brianmoooore]

Funnily enough, the last bit of fixed wiring I installed was using 0.5mm2 flex. Wasn't in a building or 230V though.
The problem of poor physical strength of 0.5mm2 T&E could be overcome by incorporating strong string into the cable, as used to be common with flexibles.

 

[westward10]

Rule of thumb means absolutely nothing as there are many thumbs with alleged rules hanging from them.
1.0 T&E has been around in common use for at least fifty years.
2A and 5A sockets have been fitted to protective devices which exceed their rating for years in fact I have 2A sockets backed up by a 6A protective device, this is not an oversight because the socket does not require lesser protection due to the fact they support lighting appliances which will not subject them to excess current.