Armoured Electrical Cable

[DIYWell]

If you can measure the overall diameter of the cable, 15mm would be 4mm2, 17.5mm would be 6mm2 and 19mm would be 10mm2.

Current carrying capacity is dependant on how the cable is installed; cables heats up the more current they carry so it's all about how the cable can dissipate that heat safely. Electricians install fuses and breakers to limit (down rate) the current carrying capacity to protect the cables.

 

[Craig Farrall]

Ok, so you aren't able to find out based on the wording on the cable itself then?

 

[Taylortwocities]

Ok, so you aren't able to find out based on the wording on the cable itself then?

There should be more lettering, maybe further down the cable or on the opposite side. We are looking for numbers something like
3 x 2.5

Often the embossed letters go on to say something additional
See my pic. This is 6mm, 2 core cable. The figures say
BASEC CABLES 2x6 2008

Look further, report back. Thanks.

 

[Craig Farrall]

I have checked again and I can see that it says "3 x 2.5 SQ MM" - does that help?

 

[Taylortwocities]

Yes. The cable you have is 3core, 2.5mm²
Max current is about 30amp, assuming it is XLPE cable.
What will be the length of the cable run?

 

[Craig Farrall]

Is there anyway of me knowing if this is an XLPE cable? Just to make certain the max is about 30amp (which would be ideal).

The cable run will be about 20m run.

 

[Taylortwocities]

Is there anyway of me knowing if this is an XLPE cable? Just to make certain the max is about 30amp (which would be ideal).

The cable run will be about 20m run.

IIRC, XLPE 6943X. Should also be marked on the cable.

In any case 2.5mm will probably not be big enough for the loads you have in mind. There’s now no such thing as a 30amp MCB, so your max will probably be 25amp (if your cu has such a thing in its range). Or the circuit could be run from a switched fuse.
I’d be looking at 6mm for a run of 20metres or the distance will kill you with volt drop.

Can’t (won’t) design circuits like this. It’s a new circuit so you’ll need a Registered electrician to carry out a proper cable size calculation and recommend a route snd connection strategy.

 

[chivers67]

Have you enough to run two lengths? If not then as TTC says

 

[Risteard]

Yes. The cable you have is 3core, 2.5mm²
Max current is about 30amp, assuming it is XLPE cable.
What will be the length of the cable run?

Do you suspect that it will be connected to terminals suitable for 90 degree operation? I certainly doubt that.

 

[JohnW2]

In any case 2.5mm will probably not be big enough for the loads you have in mind. There’s now no such thing as a 30amp MCB, so your max will probably be 25amp (if your cu has such a thing in its range).

The only loads which have been mentioned explicitly are a ("13A") hot tub and "at times a heater". We don't know what the latter does, or might, mean, but many a heater (fan heaters, many 'panel' heaters etc.) are only about 2 kW, so the peak demand might only be 22A or so..

Kind Regards, John

 

[chivers67]

That maybe but the OP also mentions "Future proof" & a "few things".


Regards Chivers

 

[winston1]

You can’t future proof as no one knows the future. Who would have thought 20 years ago that we would be having hot tubs, instant hot taps, and EV chargers to mention a few?

 

[Risteard]

You can’t future proof as no one knows the future. Who would have thought 20 years ago that we would be having hot tubs, instant hot taps, and EV chargers to mention a few?

I presume you are referring to chargepoints rather than chargers?

 

[JohnW2]

That maybe but the OP also mentions "Future proof" & a "few things".

He does, but provided the "few things" are not heaters, they are unlikely to require much power for appreciable periods of time - and it might be necessary for him to think again about the 'future proofing'.

This whole exercise is a bit back-to-front, and is presumably essentially about money/cost Given that the OP is considering using cable he has been given, rather than determining, and then buying, whatever cable would be required for his possible future needs, I can but presume that he does not want to future-proof "regardless of cost".

Kind Regards, John

 

[Agile]

I would suggest you think more simply.

If a voltage is applied to something that has a resistance a current will then flow which is roughly proportional to the voltage applied.

So if 230v is applied to a 10 ohm resistor then a current of 10 amps will flow.
When cables are used to carry higher currents their current carrying ability depends partly on how they are mounted. For example if closely fitted to a metal cable tray they can carry a higher current as the metal helps to carry away the heat produced.

If the cable is run under loft insulation it cannot dissipate much heat and need to be significantly de-rated.