Specification of cable to carry power over about 600 metres

[MattGSW]

I want to run power to an endpoint about 600 metres away to power some security cameras and some power points. I'll be using a qualified electrician to hook everything up but I'm happy to dig/refill the trench and supply cable and piping as necessary.

What kind of thickness of cable would be required for this sort of distance?

Thanks!

 

[SparkyChick]

It all depends on the anticipated load. Given it's a long run I would be wanting to know the power characteristics of the camera and what you were planning on plugging in the power points so I could run some cable calculations.

Given the price of copper is pretty high right now, a more precise measurement than 'about 600m' would also help, as would avoiding convoluted cable routes.

To give you some idea, unless I'm much mistaken to provide 13A at the far end over a distance of 600m and be within acceptable voltage drop limits for power, you're going to need a 35sq mm cable (1.35mV/A/m => 600m x 13A x 1.35mV/A/m => 10.530v - Limit for power is 5% of supply which is around 12v).

It's going to be an expensive cable run.

 

[DPG]

With the amount of work and cost of cable it may be worth looking into solar/battery power?

How are the cables going to send their video feed out of interest?

 

[Rockingit]

It all depends on the anticipated load. Given it's a long run I would be wanting to know the power characteristics of the camera and what you were planning on plugging in the power points so I could run some cable calculations.

Given the price of copper is pretty high right now, a more precise measurement than 'about 600m' would also help, as would avoiding convoluted cable routes.

To give you some idea, unless I'm much mistaken to provide 13A at the far end over a distance of 600m and be within acceptable voltage drop limits for power, you're going to need a 35sq mm cable (1.35mV/A/m => 600m x 13A x 1.35mV/A/m => 10.530v - Limit for power is 5% of supply which is around 12v).

It's going to be an expensive cable run.

If it's ONLY camera's then I'd be tempted to say that VD doesn't apply based on a) dedicated equipment and b) the spec on them probably states a supply voltage of 90-250v. However, that doesn't overcome ADS unless the source CPD was probably a 3a FSU (haven't checked the maths on that).

Might also be able to achieve the same for sockets if again they are locally down-fused by a significant value as that way the design current rather than a possible current load comes into play. In which case for a 3A fuse we're down to 6mm values.

 

[Rockingit]

Of course, if you're locally downfusing to that extent then you'd probably do the maths on a 5s circuit for ADS to a small board...

 

[MattGSW]

It all depends on the anticipated load. Given it's a long run I would be wanting to know the power characteristics of the camera and what you were planning on plugging in the power points so I could run some cable calculations.

Given the price of copper is pretty high right now, a more precise measurement than 'about 600m' would also help, as would avoiding convoluted cable routes.

To give you some idea, unless I'm much mistaken to provide 13A at the far end over a distance of 600m and be within acceptable voltage drop limits for power, you're going to need a 35sq mm cable (1.35mV/A/m => 600m x 13A x 1.35mV/A/m => 10.530v - Limit for power is 5% of supply which is around 12v).

It's going to be an expensive cable run.

Thanks! Expensive is probably the word... though I'm having a hard time getting a price for a conductor area (did I get that right?) of 35 sqmm.

 

[MattGSW]

With the amount of work and cost of cable it may be worth looking into solar/battery power?

How are the cables going to send their video feed out of interest?

Yes, sounds like it might be simpler. I'd planned to run the cable down suitable piping and run fibre optic alongside for the network connection. 4G and battery/solar is beginning to sound more reasonable

 

[DPG]

Yes, sounds like it might be simpler. I'd planned to run the cable down suitable piping and run fibre optic alongside for the network connection. 4G and battery/solar is beginning to sound more reasonable

At least you were considering fibre. I'd visions of you trying to send it down 600 metres of coax or RJ45!

 

[Rockingit]

Thanks! Expensive is probably the word... though I'm having a hard time getting a price for a conductor area (did I get that right?) of 35 sqmm.

For that length you'll want to get on the phone to suppliers for deals rather than hit Google but I'd reckon on around £15/m at the moment. Also - you'll need a forklift and the correct cable reel supports for that size of length!

 

[MattGSW]

For that length you'll want to get on the phone to suppliers for deals rather than hit Google but I'd reckon on around £15/m at the moment. Also - you'll need a forklift and the correct cable reel supports for that size of length!

Sounds like I'm going to be biting off about 599 more meters than I can chew

 

[SparkyChick]

Thanks! Expensive is probably the word... though I'm having a hard time getting a price for a conductor area (did I get that right?) of 35 sqmm.

Yes, but it as @Rockingit points out in post #4 my figures are based on an anticipated maximum load of 13A. You should definitely take a look at his posts because if your can be fairly precise with your design currents and they are much smaller, the cable can be significantly smaller.

 

[Timbo]

35mm² 3 core swa £13.50/m from

35mm 3 Core SWA Armoured Cable

35mm 3 Core Armoured Cable available for some of the best prices online with fast, free delivery on orders over £100 excluding VAT.

armouredcable.net

 

[brianmoooore]

The 13A sockets are what puts the cost up. What are they for?

 

[Rockingit]

35mm² 3 core swa £13.50/m from

35mm 3 Core SWA Armoured Cable

35mm 3 Core Armoured Cable available for some of the best prices online with fast, free delivery on orders over £100 excluding VAT.

armouredcable.net

35mm the armoured would be fine for CPC so only need 2 core. That should reduce the cost of a 600m run by at least a pint.

 

[Rockingit]

In fact, thinking about it some more, if it’s going in a duct anyway then I’d be doing the maths for concentric service cable and a TT…

And thinking even more outside the box, for that ££££’s of cable two small LV-MV MV-LV transformers might even be cost effective with a much reduced conductor size cable. Outside the scope of BS7671 but doesn’t make it a bad engineering solution.

 

[SJD]

There was a similar post a few months ago that might be of interest, which also happened to be about 600m:

What type and size of cable for a long underground run

Hi there, I have a customer (I'm in IT, not an electrician, and am just getting information at this stage before appointing a contractor early next year) who is planning on having fibre and a switch in a couple of fields for events. We will be providing an IP65 cabinet with mains power, a fibre...

www.electriciansforums.net

 

[MattGSW]

The 13A sockets are what puts the cost up. What are they for?

Thanks - security camera, recharge points for a robot mower, plug for laptop and a wifi point at most. I get the feeling I'm out of my depth on this one and not even asking the right questions. Sounds like I should dig the trench and leave everything electrical to a pro!