Cable run

[paulpa]

I need to work out cable size to run a temporary cable 100m to a tent to power approx 2kw of equipment. The cable will be run and protected by an RCD. Required for one evenings party.

Appreciate power loss etc, so can you help with the cable size?

 

[PrenticeBoyofDerry]

T&E
Required Cable Size 4 mm
Voltage Drop 9.57 Volts.
Percentage Drop 4.2%
Current Load 8.00 Amps
Max Cable Load* 27.0 Amps

SWA
Required Cable Size 4 mm
Voltage Drop 8.70 Volts.
Percentage Drop 3.8%
Current Load 8.00 Amps
Max Cable Load* 42.0 Amps

Hi-Tuf
Required Cable Size 4 mm
Voltage Drop 9.57 Volts.
Percentage Drop 4.2%
Current Load 8.00 Amps
Max Cable Load* 32.0 Amps
Kind help of http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html

You will need to use a suitable cable for the environment in which it runs, so protection must be offered either by containment or by cable sheathing. The use of containment could effect the CCC of cable.

 

[ban-all-sheds]

SWA
Required Cable Size 4 mm
Voltage Drop 8.70 Volts.
Percentage Drop 3.8%
Current Load 8.00 Amps
Max Cable Load* 42.0 Amps

That's a 3-phase calculation using XLPE.

In this case the loading won't drive the cable over 70° so XLPE is irrelevant, but unless you specify 2-core cable in the TLC calculator it will assume a 3-phase application.

 

[ban-all-sheds]

Appreciate power loss etc, so can you help with the cable size?

What about earthing?

What type of supply do you have? Should you export the earth?

 

[paulpa]

Coming from the main consumer unit.

 

[flameport]

Hire a small generator - it will be cheaper and safer.

 

[PrenticeBoyofDerry]

That's a 3-phase calculation using XLPE.

In this case the loading won't drive the cable over 70° so XLPE is irrelevant, but unless you specify 2-core cable in the TLC calculator it will assume a 3-phase application.

Is it?
So if you use calculation with a voltage of 400V
Why do you get different values
Required Cable Size 1.5 mm
Voltage Drop 13.5 Volts.
Percentage Drop 3.4%
Current Load 5.00 Amps
Max Cable Load* 23.0 Amps

But anyway my mistake
SWA(PVC)
Required Cable Size 4 mm
Voltage Drop 8.26 Volts.
Percentage Drop 3.6%
Current Load 8.00 Amps
Max Cable Load* 33.0 Amps

 

[paulpa]

Hire a small generator - it will be cheaper and safer.

Not sure about cheaper as i may have the cable already. Safer... possibly

 

[ban-all-sheds]

Is it?
So if you use calculation with a voltage of 400V
Why do you get different values

It won't change the voltage for you if you select a 3-core cable.

Keep the voltage and cable type the same and just change from 2- to 3-core.

You'll see, f'rinstance, that the VD figure changes by √3/2

 

[ban-all-sheds]

It's more than a bit worrying when someone planning to run a cable to a marquee thinks that the answer to

"What about earthing?

What type of supply do you have? Should you export the earth?"

is

"Coming from the main consumer unit".


Please get an electrician.

 

[paulpa]

It's more than a bit worrying when someone planning to run a cable to a marquee thinks that the answer to

"What about earthing?

What type of supply do you have? Should you export the earth?"

is

"Coming from the main consumer unit".


Please get an electrician.

Worrying?
Yes i will get an electrician, it is a charity event i have been asked to look at POwer.
When i find an electrician that offers his service for free to support the charity i will. At this point i am asking for advice on the cable not how i connect it.
I assume the consumer unit is earthed, and i assume the cable i get will have an earth. The equipment will be earthed.
Single phase supply on 100A main fuse.
Looking to run this via a 32A circuit.
Ideally looking to make a 100M extension cable protected from the consumer unit running 100M that can carry upto 2KW.
Looks like 6mm cable is required and best to use armoured cable .
And yes a generator is looking a cheaper option.

 

[Robin0577]

Hmmm...

At the risk of stirring things up here, the words "temporary" and "marquee" would suggest to me that its BS7909 we should be working with here as opposed to BS7671. Not that this changes anything with regard to the risks of exporting an earth or the need to calculate voltage drop, its just that I would be looking at doing it with H07RN rubber flex protected by ramps as appropriate, RCD at the supply end and BS4343 plugs and sockets, not with hardwired SWA and certainly not T&E. Earthing wise, the generator may still be the better option of course

 

[paulpa]

Generator it is.

 

[westie101]

Bear in mind that a 2.5 kW generator is not rsted to supply that load continuously, you'd be better looking for a 7.5 or 10 kVA site supply generator
One of these http://www.aplant.com/hire/small-diesel-generators/
If you talk nicely to some of the plant hire companies they will do good deals for charities I have found

 

[ban-all-sheds]

Yes i will get an electrician, it is a charity event i have been asked to look at POwer.

The problem is that you don't know enough, and charitable status does not include exemption from the laws of physics.

When i find an electrician that offers his service for free to support the charity i will. At this point i am asking for advice on the cable not how i connect it.

It's not as simple as that - connecting a cable, of any type or size, may not be safe.

I assume the consumer unit is earthed, and i assume the cable i get will have an earth. The equipment will be earthed.

Exporting earths from one equipotential zone to another is not a good idea.

Ideally looking to make a 100M extension cable protected from the consumer unit running 100M that can carry upto 2KW.

What do you think you mean by "extension cable"?

Looks like 6mm cable is required and best to use armoured cable .

1) 100m of 6mm² SWA is going to set you back £250 - £300.

2) SWA cannot be casually connected to a CU - see this: //www.diynot.com/wiki/electrics:swa-gland. A typical plastic domestic CU will probably have neither the space nor the strength to accommodate SWA glanded into it.

3) What would you do with it at the marquee end?

And yes a generator is looking a cheaper option.

There are more important factors than price, charity or no.

You are so far into your zone of unknown unknowns that you cannot begin to spec this job or make design decisions.

Whether you have to pay or not, you have to get an electrician, there simply is no other option. If you can't find one who will do the work for what you can afford to pay then you cannot host the event, it really is that black and white. Can you say "Public Liability Insurance", for example? Have you looked into local authority licensing requirements?

As well as not being exempt from the laws of physics, charities are not exempt from the laws of the land.

[EDIT]Wiki link corrected[/EDIT]