0.5mm T&E cable now available.

[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.

 

[pc1966]

Certainly seen 1mm T&E in 80s installation.

 

[7029 dave]

Certainly seen 1mm T&E in 80s installation.

When moved into a new council house in 1977 that was wired in T&E , wylex metal clad 8way with BS3871 mcb's.

 

[marconi]

I think 0.5mm2 t &e should be marked up along its sheath ( in a noticeable way so amateurs ought to see it) with the maximum circuit breaker size as E2.

 

[loz2754]

Theoretically the 5A plug/socket is not protected using a 6A MCB

The MCB is not there to protect the plug or the socket.

 

[Cagethethird]

Problem with 0.5mm T+E, if the apprentice misses with their hammer when clipping it they would go straight through the cable.
At least I know one that would.