Is 0.75mm Flex in conduit behind tiles and tile backer sufficient for led lights (6w) or Fan (4w)?

[benhurr]

Hello to all.
I know now that 1mm T&E would be better for lights, but legally is 0.75mm Flex in conduit behind tiles and tile backer sufficient for led lights (6w) or Extractor Fan (4w)?
1 out of 3 quoting electricians said that those need to be replaced. Is it really that bad? Looking at the specs it is more than sufficient (0.75mm handles 6amp 1380 Watt) and not being exposed to movement and covered by conduit etc.

 

[Spoon]

1 out of 3 quoting electricians said that those need to be replaced.

Did they say why? Quote a reg number?

0.75mm handles 6amp

Depends on what the data sheet says. It may be 6A when installed in free air. What about the derating factors for conduit?
Any ferrules used?

 

[davesparks]

What is providing overcurrent and fault protection for this cable?

 

[benhurr]

What is providing overcurrent and fault protection for this cable?

32mA RCD in CU

 

[benhurr]

Did they say why? Quote a reg number?



Depends on what the data sheet says. It may be 6A when installed in free air. What about the derating factors for conduit?
Any ferrules used?

can use ferrules if necessary, the ends are not wired at the moment

 

[davesparks]

32mA RCD in CU

RCDs don't provide overcurrent protection, this will be provided by a fuse or MCB. Unless it is an RCBO where it is provided by the overcurrent portion of the RCBO.

 

[benhurr]

RCDs don't provide overcurrent protection, this will be provided by a fuse or MCB. Unless it is an RCBO where it is provided by the overcurrent portion of the RCBO.

yes fuse is possible , fused spur maybe. Light and fan is on different circuits. Fused spur for fan definitely (not for light)

 

[benhurr]

RCDs don't provide overcurrent protection, this will be provided by a fuse or MCB. Unless it is an RCBO where it is provided by the overcurrent portion of the RCBO.

it is part of light circuit with is connected to MCB and RCD in CU

 

[Spoon]

How much of this project has been installed?

 

[benhurr]

How much of this project has been installed?

this cable will only serve 1 light , the rest of the circuit is on TE cable. this room 4 led lights in total. Together with the rest of the light circuit it will be about 12 lights (including). Fan is on outlet circuit.

 

[benhurr]

How much of this project has been installed?

at this moment only spare cable for fan and one short cable for mirror light are installed because those are under tiles .this cable will only serve 1 light , the rest of the circuit is on TE cable. this room 4 led lights in total. Together with the rest of the light circuit it will be about 12 lights (including). Fan is on outlet circuit.

 

[Julie.]

Did they say why? Quote a reg number?
....

I would say 524.1

It may be in flex but as it's used as fixed wiring.....

 

[benhurr]

I would say 524.1

It may be in flex but as it's used as fixed wiring.....

So will it fail b. Control based on this?

 

[Julie.]

It would not be compliant with the wiring regulations, the minimum size conductor for lighting circuits is 1mm^2

If there is a fused connection unit, or plug with a suitable fuse for the flex then it would comply.

The principle is that fixed wiring is protected by the mcbs or rcbos or fuses in the consumer unit and must provide disconnection times generally of 0.4s in the case of a fault.

Flex doesn't have to do this as it's usually associated with an appliance or so on, so it must have it's local fuses, and shouldn't really be used as fixed wiring, although there isn't a specific regulation preventing it.

 

[benhurr]

It would not be compliant with the wiring regulations, the minimum size conductor for lighting circuits is 1mm^2

If there is a fused connection unit, or plug with a suitable fuse for the flex then it would comply.

The principle is that fixed wiring is protected by the mcbs or rcbos or fuses in the consumer unit and must provide disconnection times generally of 0.4s in the case of a fault.

Flex doesn't have to do this as it's usually associated with an appliance or so on, so it must have it's local fuses, and shouldn't really be used as fixed wiring, although there isn't a specific regulation preventing it.

So to recap adding fused unit like a maintenance switch will not make it compliant? Even Just for short 1m leg of wiring?

 

[Julie.]

So to recap adding fused unit like a maintenance switch will not make it compliant? Even Just for short 1m leg of wiring?

Fused connection unit.

What is a maintenance switch?

 

[benhurr]

Fused connection unit.

What is a maintenance switch?

Fused spur switch ?

I think here is the answer suggestion that 0.75 on lighting is acceptable .75mm flex used from junction box to downlights - https://www.electriciansforums.net/threads/75mm-flex-used-from-junction-box-to-downlights.171264/
or maybe they are referring to an older regulations.
I can see now the reg It is clearly saying 1mm for lighting circuits 220v regardless of flexing.
But how about this way:
We remove the led driver from light fitting and place it in a box outside the room, this way it is going to be low voltage going via 0.75mm with is within current regulations.
The wire is less than a meter long.

To be honest it doesn't make much sense if this flex 0.75mm allowed on flexible applications like hanging lights but not good inside the wall in conduit behind tiles and backing board (even if it will be very short part of it)

 

[davesparks]

If it's in conduit the electrician can just use the bit of flex to pull through whatever cable they feel is required.

We can all give you our own opinions on what is/is not acceptable but ultimately it is down to the electrician who does the work and signs it off to make the decision and put their name to it.

A lot of electricians are likely to refuse to connect or sign off a cable which the customer has installed themselves regardless of what size or type it is.

 

[benhurr]

But how about this way:
We remove the led driver from light fitting and place it in a box outside the room, this way it is going to be low voltage going via 0.75mm with is within current regulations.

If it's in conduit the electrician can just use the bit of flex to pull through whatever cable they feel is required.

We can all give you our own opinions on what is/is not acceptable but ultimately it is down to the electrician who does the work and signs it off to make the decision and put their name to it.

A lot of electricians are likely to refuse to connect or sign off a cable which the customer has installed themselves regardless of what size or type it is.

 

[Pretty Mouth]

Interesting. The way I read table 52.3, from left to right, 0.75mm2 flex is permitted.