Garage power

[Electrapeace]

If I connect 4mm2 armoured from a 32A mcb to a garage 30metres away do I need to sub-fuse box in the garage or can I just use it as a radial circuit?
The garage will have two sockets and fused down lighting.

 

[Taylortwocities]

Why 'must' this be a prime aim in a garage installation of two sockets and some lights?

I absolutely agree. Nothing needed In the outbuilding more than the sockets and an SFCU for the lights.

60898's won't fully discriminate whatever you fit.

Absolutely. Some people really dont understand this.

 

[MDJ]

do you really need 32a at the garage ?

if you don’t then you Could save yourself some money and use 2.5 on a 20a

Or the 4mm cable on a 20.

 

[Dustydazzler]

Or the 4mm cable on a 20.

but that would cost the same , 2.5 is cheaper is what I was getting at

 

[MDJ]

but that would cost the same , 2.5 is cheaper is what I was getting at

Yes but a 2.5 running 30 Mtrs doesn’t sit Right with me, call it old fashioned thinking on my part ?

 

[Dustydazzler]

Yes but a 2.5 running 30 Mtrs doesn’t sit Right with me, call it old fashioned thinking on my part ?

30m is nothing , 2.5 on a 20a device wouldn’t even get warm...

 

[John-SJW]

An issue with 60m of 2.5mm is voltage drop. In a district where voltage fluctuates, this may be an issue. In my place it is always 249-250 volt, so I am lucky, other may not be. So a 4mm cable may be the way to go, even though it appears oversized for the current it handles.

 

[pc1966]

This is when the OSG is your friend, a quick look at Table 7.1(i) has some quick answers to most initial guess of current & length combinations.

However, the OP said the client wants 32A option for the future so that really pushes for 4mm cable now. Also the difference between 2.5mm and 4mm 2-core SWA is around the 50p/m mark so for 30m or so run around £15 and compared to the labour, etc, involved it is hardly worth arguing over!

 

[Strima]

In my place it is always 249-250 volt

But we still use a nominal voltage of 230 at the design stage. Can you guarantee in ten years time that the voltages will be the same?

 

[Dustydazzler]

An issue with 60m of 2.5mm is voltage drop. In a district where voltage fluctuates, this may be an issue. In my place it is always 249-250 volt, so I am lucky, other may not be. So a 4mm cable may be the way to go, even though it appears oversized for the current it handles.

60m

i though the distance was 30m ?

 

[John-SJW]

But we still use a nominal voltage of 230 at the design stage. Can you guarantee in ten years time that the voltages will be the same?

Not at all. But as a transformer is not far from me it is a good bet it will remain that way in my case. But generally you are right.

I recall one Dutch guy who said the British oversize cables. He said, with widespread adoption of LED lights you are still installing 1.5mm lighting cable when 1.00mm is more than adequate. Lightly used rings are oversized with a total of 5mm. But the oversizing may compensate, even if ever so slightly, over voltage drop.
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60m

i though the distance was 30m ?

typo. approx 98 foot, a fair distance in a domestic house. Then wires off that.

 

[pc1966]

He said, with widespread adoption of LED lights you are still installing 1.5mm lighting cable when 1.00mm is more than adequate.

You do get 1mm for light circuits and it is often used.

The problem is the IET regs have 1.5mm as smallest for power circuits (not sure exactly why, might be for mechanical reasons, or a throwback to the days of 15A rewirable fuses being the next size up from 5A) so for many a stock of 1.5mm is more generally useful stuff to have for odd fused spur, etc, as well as for lights.

 

[John-SJW]

Also the difference between 2.5mm and 4mm 2-core SWA is around the 50p/m mark so for 30m or so run around £15 and compared to the labour, etc, involved it is hardly worth arguing over!

At TLC 2.5mm 3 core swa for 50m is £50.52. 4mm for 50m is £99.60. x2.

 

[Strima]

installing 1.5mm lighting cable when 1.00mm is more than adequate

Just poor design using 1.5mm when 1.0 would suffice in the vast majority of installations.

As an aside I use 1.0mm when installing new but a lot of installations in my area use 1.5mm so I use that when modifying or repairing.

 

[pc1966]

At TLC 2.5mm 3 core swa for 50m is £50.52. 4mm for 50m is £99.60. x2.

Do they need 3-core?
Why 50m, I thought the run was 30m?

 

[Spoon]

Do they need 3-core?

It might not be needed but personally I would use 3 core. It's only 25p more per meter, so an extra £7.50 for 30 meters, which isn't that bad.