Hi,

Lets go through my interpretation.

The cable is none armoured but in a low mechanical impact area, but it is low level so might have fauna interactions, so would possibly need mechanical protection for installations outside (Section 522), the datasheet I found doesnt mention any ratings, you mention it running along the top of pipe, if it was inside Galv pipe then you could deem it suitable due to that being the protection (the protection would be for mechanical impact but also if there is possibility of fauna interaction, with it being at low level, could be assessed away if deemed unlikely enough).

If you did run it along the top of the galv pipe, that pipework would need to make sure it is properly bonded to your installation, if it isnt already. (Edited, see replies below)

SWA cable would deal with both issues.

As the setup is using, by the sounds of it, standard plugs I would personally want to have it designed to a standard radial final circuit (assumed that was the setup you were going for?) (Appendix 15, Fig 15B), which based on your measurements you would probably need to upgrade it to the 32A radial and 4mm2 that can cover up to 75m2, as the 20A version can only cover 50m2 (although the 2.5mm2(20A) could be argued to be suitable with the reduced expected loads), the MCB would need to be RCD protected (Section 411.3.3), if it isnt already.

I say I would prefer a normal socket installation, as I would be thinking this installation would be staying even after you leave the house, so would people have an expectation on the installation to behave as a normal socket installtion and a reduced MCB may cause nusiance tripping in this regard, if they overload your reduced MCB, by using multiple sockets in different ways to yourself. However if it wont be staying, then I would say as long as it is appropriately labelled, you could have a reduced MCB feed.

From my personal point of view and my interpretation of the regs, I think the over all idea is ok, it is just the details are a little off in my opinion or the validation of some choices not communicated from your post, I provided sections of the wiring regs that can be used for further reading on the points I was using.

Feel free to correct/dispute any interpretations you dont agree with

Mike

Mike Mln said:

The cable is none armoured but in a low mechanical impact area, but it is low level so might have fauna interactions, so would possibly need mechanical protection for installations outside (Section 522), the datasheet I found doesnt mention any ratings, you mention it running along the top of pipe

Agreed ... SWA would often be chosen for this purpose.

Mike Mln said:

If you did run it along the top of the galv pipe, that pipework would need to make sure it is properly bonded to your installation, if it isnt already.

Why ? It would not be an exposed-conductive-part, and extraneous-conductive-parts only require bonding within buildings?

gkenyon said:

Why ? It would not be an exposed-conductive-part, and extraneous-conductive-parts only require bonding within buildings?

If it was running along the top of the galv pipe with non armoured I would then be treating that galv pipe as support medium (like tray), and since it has the potential to be live if the cable was damaged, I would as a preference want it bonded at some point, it would be a very fringe case for it to happen.

That was my thinking behind it.

Mike Mln said:

If it was running along the top of the galv pipe with non armoured I would then be treating that galv pipe as support medium (like tray), and since it has the potential to be live if the cable was damaged, I would as a preference want it bonded at some point, it would be a very fringe case for it to happen.

That was my thinking behind it.

I wouldn't disagree with the sentiment. However, if sheathed cables are installed on tray, ladder or in trunking, the containment is not an exposed-conductive-part. Within buildings, it's usually a very good practice to bond metallic containment, and it provides advantages in terms of EMC as well.

It's definitely not a requirement of BS 7671 though ..

and there are cases where earthing/bonding something that's neither an extraneous-conductive-part nor an exposed-conductive-part can lead to dangerous touch-voltages and touch-currents even if there were no fault. These cases occur more frequently outdoors ... in many domestic properties, you'd be very unlucky to come across those situations.,

Thank you for the information, I happily stand corrected.

Mike Mln said:

Thank you for the information, I happily stand corrected.

No problem, as I said, many domestic situations should not be a problem ... I've worked on many jobs in major infrastructure, though, where you need to be careful about accidentally exporting earth potentials from one place to another.

Season's greetings and have a very Happy New Year.

Hello Mike, thank you for your response and all the others as well. Yes, the installation will remain as it is even if I decide to leave the house.

I apologize, but I prioritize my needs, which is why I chose a 16A MCB and 2.5mm NYYY-J cable (which is a very tough cable) instead of considering others' needs. I am aware that I can use a 20A, but I had the 16A spare in my CU (although I can replace it for £3.5).

People might want to use an external hot tub with a 4 KW heater or more. My installation will not be sufficient for this. They would need to upgrade to either 4mm or 6mm twin and earth, depending on the load.

My requirements are LED lights, but I have changed my mind and will stick with the solar ones I have. I will use the sockets for a small power drill if needed for minor jobs and later possibly use a freezer in the new Keter plastic shed as shown in my diagram.

All of my sockets are 13A, 2 gang, DP IP66 switched, and in a radial circuit. The galvanized pipes will be earth bonded with external earth clamps and 4mm earth cable if needed at corners for galvanized pipe and steel PVC flex conduit.

The cable will run from the CU either 16A or 20A, which is RCD protected, to an external IP66 connection box and from there to the sockets as shown in the diagram.

The galvanized pipe is only used to support the cable and above ground 150mm secured. You can see it on pic 1 & 2. The others are behind the flower beds.

For fauna interactions and mechanical protection, I can install a 22mm PE-X pipe over the galvanized pipe to house the cable, or I can use 22mm or 25mm steel PVC flex conduit (earth bonded as well) where the cable is most exposed. What are your thoughts on this?

Wishing you all the best, have a nice Christmass and New Year.

Hi Manos,

Having it suit your needs, vs complying with the wiring regs, as it is becoming part of your installation, that is why some outdoor installations are glorified extention leads as they are outside of the regs and can just be unplugged when it comes to testing.

As I have little experience on testing installations, I cant really comment on how they would judge it.

Look at gkenyon' s comments around the bonding (he corrected my thoughts on the matter), as he mentions you wouldnt want to introduce  touch voltages and currents to something that would normally be ok.

A steel flex would be more than enough mechanical protection.

Have a nice Christmas and New Year.

Mike

Manos said:

The galvanized pipe is only used to support the cable and above ground 150mm secured.

So there is nothing inside the pipe? Why not join the corners properly (you can get right angle bends if you do not have access to a bender) and put singles inside it?

Nothing inside pipes only for support. I will get some steel flex and put cable inside for mechanical protection.

Thanks Mike for this

Thanks Mike for this