No way that I'd connect SY cable underground unless it's mechanically protected (ducted), is at the correct depth, and has warning tape.
Sounds like it all needs ripping out and redoing.
I don't think ripping out is an option as it's all been landscaped etc. Option is to get anything we can connected and installed so it's safe and to regs, or not at all. At least that's what I'm thinking having never spoken to the customer.
I have no idea if it's ducted. It seems buried in areas where no digging will occur - under flagging and concrete. Only one of the 4 lighting cables could be under soil or a garden, but it may be under the stone pathway. I think the gardener and owners will have knowledge of this, so I'd have to ask.
Have to agree with Guitarist.
Just out of interest: How many light is the cable powering? What wattage are the lights? What size & length is the cable?
The guy installed 4 separate cables, each one between 30-45 meters in length. 1.5mm cable. Actually, it was mostly 2.5mm cable, but a small part of it was 1.5mm, so i've downgraded it all to 1.5 to be on the safe side. These distances include 10m of 16mm swa distribution cable.
One cable has just one light on it at the end. The others have 5 or 6 points on each of them. There were no actual lights, just junction boxes for the lights to run off, so I allowed 100w per light for any calculations I did. Using 6 100w bulbs on the longest cable run of 35m plus 10m distribution cable, I think I calculated voltage drop at 2.6v on the light cable and 0.7v on the distribution cable, (used total design current of 24a when calculating vd of distribution cable), so 3.3v total voltage drop for the lighting cable.
The way the guy's installed the cable is that he's run 10m swa distribution cable from the garage to the back of the house. He's then run 4 sy cables under the patio flagging at back of the house, about 15m. They are cut off here, possibly with damaged ends, but probably enough slack to cut it back. He's then run 4 more sy cables in different directions, another 10-20m each. Either under stone pathways or clipped direct. 2 of the cables have no junction boxes or lights installed. Just cable, with loops where it's to be terminated with an accessory.
I was thinking if it was possible to combine these four circuits into fewer, for switching purposes. So they'd be a 10m distribution cable run, followed by around 15m of the circuit run under the patio, where it would then radiate out 2 or 3 directions, all around another 10-20m each. However, I'm not sure how this changes the voltage drop calculation when a circuit radiates like this. I can make an educated guess, but I've not found confirmation of the right way to do the calculation when a circuit radiates in different directions from one point.
SY is not suitable for this set-up and should not be re-connected
SY is not UV tolerant.
SY braiding is a screen not an armouring and doesn't provide the necessary protection in your case.
SY Braiding requires earthing but should not be used as the earth if used for LV power.
SY suitable glands should be used.
The condition of the cable already reflects its poor installation methods and unsuitability for the job i would be informing your customer its poor quality of work and cannot be re-instated.
It's looking that way based on the posts so far.
Would black insulation tape around the exposed parts of the cable be suitable or adequate to give it uv protection?
If so, and the buried parts turned out to be ducted, an internal conducter used for earthing, and suitable glands were used to connect it to the plastic ip rated boxes so the braid was earthed, would it then be ok to use?
If the buried parts turned out not to be ducted, but buried under concrete or paving, would that be ok?
I assume parts of the cable ends which have had water get into them and mould or discolouration/rust of the braiding has occurred should not be installed. If so, this isn't in every part of the installation. If there was enough spare cable to cut the water damaged ends off, and/or cut out parts of the installation where that damage has occurred and can't be cut back, ending up with a smaller circuit with none of that damage in the cable ends, would that be acceptable?
Just out of interest, if your boss has told you to suss this out, be he/she will ultimately make the decision, is there any point us giving our opinions? Surely, as a trainee, you should be learning from the one responsible for your training....
I will learn from him, but I like to develop a deeper understanding of the underlying knowledge rather than just know what to do. I can only ask him so many questions before I start to feel like I'm pushing my luck and becoming a pain. It also helps to get different viewpoints from other experienced electricians. For all I know, I could be picking up bad habits.
Personally, I like to be able to do prep work when there's an opportunity. I think looking into things ahead of time will help me learn and develop quicker.
I'm with Darkwood 100% on this one!! But as Spoon quite rightly points out, that it's more about money/costs than any other factor!!
Does that mean some electricians in this situation, for cost reasons, would still do the job as is even if the sy cable wasn't installed properly - buried cable with no ducting or poor condition ends or unearthed braiding etc? Wouldn't that be dangerous? Or did I read your post wrong? Makes me curious what my boss will do in that case.