Help/Advice with Long cable runs in garden

[Sparky28]

Domestic property



Supply number 1
6 flood lights 4x400watt= 1600 watts
250meters from board to closets corner of tennis courts

Tennis court size
23m x 10m

My calculations are suggesting a
16mmsq cable
2.4% volt drop

Would anyone have any advice for doing long distances in a garden?

• 10-16mm to a halfway point and distribute out for both circuits
• apply diversity?

Supply number 2
Driveway 150meters
Cable length 200meters from fuseboard to 15 bollards lights (15x5w)=75watts

calculations
230v
75 load
1.5mmsq cable
Volt drop 0.8%

Many thanks

 

[davesparks]

Domestic property



Supply number 1
6 flood lights 4x400watt= 1600 watts
250meters from board to closets corner of tennis courts

Tennis court size
23m x 10m

My calculations are suggesting a
16mmsq cable
2.4% volt drop

Would anyone have any advice for doing long distances in a garden?

• 10-16mm to a halfway point and distribute out for both circuits
• apply diversity?

Presumably all of the lights will be on at once if they are for a tennis court so there is no possible diversity to be applied.

I would take a 16mm submain, if that is the required size, to a suitable enclosure at the side of the tennis court. In the enclosure I'd fit a small DB to put each of the 6 floodlight positions on its own circuit.

Having each lighting position on a seperate circuit makes future maintainence and fault finding much easier.

How will this lighting be controlled?

Having a DB at the tennis court would also allow the installation of a socket relatively easily which will probably be quite useful at some point in time.

 

[Sparky28]

Thanks for reply, Yes to all floods on a same time- so your right no diversity.
I think I’m going to try 2x lutron RA2 selects or even a Quentic wifi module.
However this plan was for having the 2 cables back at the main house where the wifi would have been strong enough. But now looks like it may have to be a wise box near the tennis court.

Presumably all of the lights will be on at once if they are for a tennis court so there is no possible diversity to be applied.

I would take a 16mm submain, if that is the required size, to a suitable enclosure at the side of the tennis court. In the enclosure I'd fit a small DB to put each of the 6 floodlight positions on its own circuit.

Having each lighting position on a seperate circuit makes future maintainence and fault finding much easier.

How will this lighting be controlled?

Having a DB at the tennis court would also allow the installation of a socket relatively easily which will probably be quite useful at some point in time.

 

[davesparks]

You can still control it from the house by switching the feed to the tennis court if that is what is required.

Why the need for a wireless switching solution?

 

[DefyG]

6 flood lights 4x400watt= 1600 watts

6 becomes 4! may affect your calculations ??

Not sure Wise box has a 250m range?

 

[Pretty Mouth]

On p424 of bs7671 there is a correction calculation for operating temperature. Based on your load being nowehere near the max for the cable, it will lower your calculated volt drop, which should permit 10mm2 at 3%.

If you were prepared to allow a 5% drop, it might just about permit 6mm2.

 

[davesparks]

6 becomes 4! may affect your calculations ??

Not sure Wise box has a 250m range?

As its a tennis court I read that as 6 columns with 4 floodlights mounted on each.

 

[Sparky28]

6 becomes 4! may affect your calculations ??

Not sure Wise box has a 250m range?

Sorry about that, I need to correct that it’s 1600 watts total load
8x 200watt floods

 

[Sparky28]

You can still control it from the house by switching the feed to the tennis court if that is what is required.

Why the need for a wireless switching solution?

1600 watts total load
8x 200watt floods

Customer had ask if they can control it through there phone or app

 

[Sparky28]

1600 watts total load
8x 200watt floods

Customer had ask if they can control it through there phone or app

I did think about switch at main house but if we go down there route of fuseboard by the tennis court the double socket would only work when switch locally is on.

 

[Taylortwocities]

Just wondering about the floodlights. Are these LED, halogen or something else?

 

[pc1966]

Just wondering about the floodlights. Are these LED, halogen or something else?

I would imagine LED these days!

 

[Taylortwocities]

I would imagine LED these days!

Me too, but you never know. I saw 400watts snd wondered …

 

[pc1966]

If you were prepared to allow a 5% drop, it might just about permit 6mm2.

As far as I know, the 3% drop for lights was to avoid unpleasant variations in brightness as other lights are switched on the circuit, probably not so big an issue now with LED as they have less change in brightness versus voltage than filament.

However, if all lights are switch simultaneously then no such interactions and 5% might make for a far cheaper job.

But also check the surge from simultaneously switching them. Some companies give to limits for this in terms of MCB rating, also check the de-rating needed for any relay or contactor.

You can reduce the surge slightly by using a zero-crossing SSR, but do remember that such devices cannot be used for isolation, only for functional switching.

 

[davesparks]

As far as I know, the 3% drop for lights was to avoid unpleasant variations in brightness as other lights are switched on the circuit,

The 3% and 5% volt drop limits are there to be used in the absence of knowing tge specific tolerances of the equipment being installed.