Advice on work I've had done

[bryc-123]

Hello,

I've recently had some outside lights fitted, there is about 10 of them, all LED. The electricans took the cable from the fuse board down into my basement void where other services are running and then out to the garden. Outside they have used armoured cable, 1.5mm, about 20-30meters in total I'd have thought. But in the basement void, it's about another 20m from the fuseboard end to the outside but they have used a 0.75mm 3 core white flex cable.

The circuit breaker is 6 amps.

I don't know whether that is good or bad but to me something isn't quite sitting right having a cable half the size of the armoured cable, it looks like they've used a cable very similar to the flex hanging down on my pendants for 20m.

Should I be concerned or is it ok? Since I have had the work done I've been hearing bad things about the company I used so I was hoping someone on here could give me some advice.

Thank you.

 

[westward10]

I disagree. Table 52.3.

(I wouldn't do the install like this, I should stress. And the flex needs proper termination with bootlace ferrules. But there's nothing in the Regs that says you can't do it this way.)

Yes Table 52.3, 1.0mm for lighting circuits. Whilst some allowance is allowed for final connections if the 0.75mm is direct into the consumer unit it is undersized.

 

[happysteve]

Yes Table 52.3, 1.0mm for lighting circuits. Whilst some allowance is allowed for final connections if the 0.75mm is direct into the consumer unit it is undersized.

You have to read the table left to right.

The first column is "type of wiring system" and the first row is "non-sheathed and sheathed cables." If you're using this type of cable, then I agree minimum size is 1mm for lighting, 1.5mm for power (assuming copper).
The second row is "bare conductors" - not relevant here.
The third row is "non-sheathed and sheathed flexible cables." This is a different row from the first row, and there are different requirements. Under "use of the circuit" (2nd column) you've got "for a specific appliance" (not relevant here), and "for any other application", which is. 0.75mm.

So rather than reading it as, "lighting says 1mm, so 1mm", you start off by asking which type of cable, then what the application is, then the minimum size.

 

[bryc-123]

Yes Table 52.3, 1.0mm for lighting circuits. Whilst some allowance is allowed for final connections if the 0.75mm is direct into the consumer unit it is undersized.

So the flex cable needs to be replaced for 1mm cable?
Don't understand any of the recent posts, trying too!

 

[westward10]

So 1.0mm for lighting circuits.

 

[westward10]

So the flex cable needs to be replaced for 1mm cable?
Don't understand any of the recent posts, trying too!

Yes it needs replacing.

 

[Pete999]

You have to read the table left to right.

The first column is "type of wiring system" and the first row is "non-sheathed and sheathed cables." If you're using this type of cable, then I agree minimum size is 1mm for lighting, 1.5mm for power (assuming copper).
The second row is "bare conductors" - not relevant here.
The third row is "non-sheathed and sheathed flexible cables." This is a different row from the first row, and there are different requirements. Under "use of the circuit" (2nd column) you've got "for a specific appliance" (not relevant here), and "for any other application", which is. 0.75mm.

So rather than reading it as, "lighting says 1mm, so 1mm", you start off by asking which type of cable, then what the application is, then the minimum size.

Well having read the table from left to right I still say 1mm2 I/is the min for a lighting circuit.

 

[Pete999]

So 1.0mm for lighting circuits.

Yep no arguments with that Westy

 

[happysteve]

Well having read the table from left to right I still say 1mm2 I/is the min for a lighting circuit.

Ok, let's try this:

Which of these two descriptions most accurately describes the "flexible cable" we're talking about? Is it:

(a) "Non-sheathed and sheathed cable,"

or

(b) "Non-sheathed and sheathed flexible cable."

 

[Pete999]

So the flex cable needs to be replaced for 1mm cable?
Don't understand any of the recent posts, trying too!

w/Without the pleasure of seeing the install, and from what you have said so far, my advice would be to get it looked at by a competent Electrician

 

[Pete999]

Ok, let's try this:

Which of these two descriptions most accurately describes the "flexible cable" we're talking about? Is it:

(a) "Non-sheathed and sheathed cable,"

or

(b) "Non-sheathed and sheathed flexible cable."

b

 

[westward10]

Ok, let's try this:

Which of these two descriptions most accurately describes the "flexible cable" we're talking about? Is it:

(a) "Non-sheathed and sheathed cable,"

or

(b) "Non-sheathed and sheathed flexible cable."

If 0.75mm was suitable for lighting circuits manufacturers would produce T&E in this size.

 

[happysteve]

b

Great, so we go to that row of the table (near the top of page 145 in the blue book, or page 134 of the old yellow book). Now read across for application, is it:

(a) for a specific appliance? (no)
(b) for any other application? (yes)
(c) extra-low voltage circuits for special applications? (no)

Minimum size for (b) is 0.75mm

If 0.75mm was suitable for lighting circuits manufacturers would produce T&E in this size.

No, because T&E uses solid (or, for larger sizes) stranded copper conductors, rather than flexible conductors. The minimum size for these is 1mm, and for good reason - they'd be too easy to break if smaller than 1mm.

Have you ever wondered why the cpc on 1mm T&E is not smaller than 1mm? It's not because of the adiabatic. It's because it would break too easily.

 

[happysteve]

... but in response to the original poster: the installation method is "unconventional" to say the least, you should certainly have got an Electrical Installation Certificate as the work involves the provision of a new circuit, and the work should have been notified to Building Control. Unless the flex has had bootlace ferrules put on the end of it before termination in the consumer unit, it has not been installed correctly.

 

[westward10]

(b) for any other application, no it is lighting. The cable is undersized.

 

[Pete999]

... but in response to the original poster: the installation method is "unconventional" to say the least, you should certainly have got an Electrical Installation Certificate as the work involves the provision of a new circuit, and the work should have been notified to Building Control. Unless the flex has had bootlace ferrules put on the end of it before termination in the consumer unit, it has not been installed correctly.

Away from the discussion about 1mm or 0.75mm, who or what sort of person would wire the garden lights in 1.5mm3 SWA cable, and then lash it on to a length of 0.75mm2 flex, answers on a post card please.