what size cable - Garden consumer unit

[runk]

Hi,

Firstly I will not be carrying out the electrical work, I will hire an electrician.

I currently have a trench open in the garden so want to take the opportunity to bury an armoured cable for future projects. I plan to have a garden sauna, some low volt garden lights along with a few 13A sockets.

I understand the sauna need it's own supply; my question is does the sauna need it's own dedicated cable and consumer unit from the house, meaning I would need a second cable and consumer unit for lights etc. Or can I run one big cable to one garden consumer unit which everything can run from?

planning to run a 10mm armoured cable, would cover everything? distance of cable run will be around 35-40m

thanks in advance.

 

[davelx]

You need to engage your electrician and discuss with him what cable size is required and how much of the work he is happy for you to do. He's the one who has to sign the certificate saying that he designed, installed and tested the work.

 

[chivers67]

Run a Screened Cat6 with it use a hosepipe or duct to protect it. I ran 10mm to my Garden room for sockets the Electrician you hire will probably do the same or 16mm, really depends on the power consumption the Sauna will require.

 

[Taylortwocities]

40metres is a long distance and volt drop will be a serious consideration. As chivers said

really depends on the power consumption the Sauna will require

you need to either

1. get your electrician on board and have the installation designed properly as he/she is going to have to sign it off. or
2. just install sizeable twin-walled cable duct like this
https://www.tlc-direct.co.uk/Products/FXKVR75.html your electrician can then pull in the SWA cable when he/she gets there.

 

[Robin0577]

What TTC said....

Don't bury a cable bury a duct. With a rope in it. Bury it "beyond any reasonably expected digging". Generally considered to be at least 450mm deep. Place yellow warning tape about 100mm above the duct as you fill the trench. Take photos, and include something, ideally a ruler, to prove the depth.

While you're at it, might as well bury 2 ducts, one for power, one for data. Perhaps even 3, if you're going to want a water supply down there.

Ideally, power ducts should be black, data ducts green, and water ducts blue.

 

[Taylortwocities]

bury a duct. With a rope in it

The duct in my link includes a draw-in wire .

 

[ericmark]

I plan to have a garden sauna, some low volt garden lights along with a few 13A sockets.

The main problem is the equipotential zone. With a sauna you want the area you will step on when you leave it to be the same voltage as the water in the sauna, there are a few ways to do this, we start by looking at the supply, we can have TN-S, TN-C-S, TT, and IT supplies, and the requirements depends on what supply you have.

Also, the sauna can be class I or class II this also changes what is required.

Low voltage is 50–1000 volts, so 230 volts is low voltage, I will assume you mean extra low voltage (under 50 volts) the is separated extra low voltage (SELV) functional extra low voltage (FELV) and protective extra low voltage (PELV) to advise we need to know which.

The 13 amp socket also has a problem, clearly needs some protection, this can also vary between TN-S, TN-C-S, TT, and IT supplies.
It will likely need a RCD.

This is why people say get an electrician, it is so easy to give wrong advice, as we have no idea what you are doing. We are not trying to drum up business.

 

[runk]

thanks for advice, think best to just bury the conduit as you say then electrician can pull through. or get a wood burner

do you think a data cable is worth it, can't think why I would need it. are you thinking additional garden wifi node

 

[blup]

10mm SWA

 

[SUNRAY]

As has been said it is your electricians responsibility to get it right and this example has no easy answer, get him on board soonest. By all means come back for forther advice if you wish to double check.

In the meantime I have only worked on one sauna heater which I knew the power of and it was 13KW - I have no idea how representative this is but TLC cable calculator shows the demarcation between 10mm² and 16mm² at 11.9KW, same results at 35m too

 

[morqthana]

or get a wood burner

Neither healthy nor environmentally friendly.

 

[flameport]

do you think a data cable is worth it, can't think why I would need it

Not needed at all unless you or others intend to use a phone, tablet, computer, laptop, security camera, smart speaker, television, smart lighting or most other modern devices at the location.

 

[Ragnar_AT]

Most sauna heaters I‘ve seen were 6 or 9 kW. Smaller ones are available too.

 

[SUNRAY]

Most sauna heaters I‘ve seen were 6 or 9 kW. Smaller ones are available too.

That sounds much more managable, my sauna experience is very limited.