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Last week we had an electrical point installed at the bottom of the garden (about 15m from the house). The cable runs alongside the property boundary. The electrician did not bury the cable as the weather was “so hot” that day and advised that the cable needs to be buried 50cm underground. Obviously I’m very annoyed, and that’s a separate story. I’ve started to dig out the trench where I can but have two questions:

  1. Can the cable be left as it is (on the ground/on the ground with a protective Hard plastic cover over it) for the section where is runs under a row of conifers?

  2. How to best protect the cable for areas where it cannot be buried (there are two trees along the boundary and so I won’t be able to dig the trench under their roots). The cable will have to come back up from their trench, over the roots, and back down).

Finally, can I check I am doing the right thing by burying what I can; putting a warning tape over it; filling in the trench; putting something like wooden sleepers down that length of garden as an extra measure/reminder that there is cabling there?

Many thanks

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    What is the voltage and what type of cable was installed? Get the electrician back to bury it on a cooler day...
    – JACK
    Jul 3 '20 at 12:08
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    Where are you on this planet? Jul 3 '20 at 13:58
  • Also, is using a "wet" trenchless technique to go under the culprit roots an option here? Jul 3 '20 at 20:15
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Was this guy an actual licensed electrician? Was there a permit pulled for this work? Did the building inspector sign-off on the work?

Of these questions I suspect the answer is "no" to all of them! Even if #1 is "yes" clearly he's incompetent and/or lazy.

Anyway, what you have is unacceptable and the wire should be protected from the elements and from damage. Simply laying it on the ground, even with some type of warning tape is not going to change that.

The line needs to be buried but before doing that you need to determine if the wire used is rated for direct burial. If should have a "UF" designation on it. UF wire is more expensive than non-UF types and that's what concerns me regarding your "electrician". He cut corners on the installation, he may have cut corners on the materials as well.

Also, this type of circuit (i.e. outdoor) needs to have a GFCI breaker installed. Where did the hookup to existing power happen? Did he run a new circuit from the panel or did he just splice into an existing circuit?

In my opinion a license professional electrician would NEVER do such shoddy and incomplete work. Hopefully you didn't pay this clown yet.

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    I think they're outside the US, which means that their direct buried cables will be designated differently, and their differential (RCD) protection works differently as well Jul 3 '20 at 13:58
  • The op mentions conifers direct burial is probably not feasible but rigid metallic would be ok here at 6”. Plus 3 phase comments.
    – Ed Beal
    Jul 3 '20 at 16:02
  • +1 Since location was not specified and questions on this site are intended to be potentially helpful to future readers, this answer hits the mark for anyone from the US who might be searching for an answer to a similar question in the future. Jul 4 '20 at 10:48
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In the US you could use rigid metallic conduit and only have to dig 6” but based on your cm & m measurements you are in a different location, left on the ground would not be legal in any on the countries I have worked but some have no standards. I would want to protect the cable.

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As others have said you would need to check your local codes, but here in North America if the cable is designated as "direct burial", it has to be 18" minimum under the surface, which is 46cm, so I'm thinking that's what he was referring to when telling you to bury it 50cm. You cannot (again, here) run it above ground around trees and such, it's underground all the way or up above ground in approved conduit, generally rigid galvanized steel if not physically protected from damage. That then means junction boxes for the transitions etc.

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  • Well, you can run it as a full-blown aerial cable run on a messenger, but that's a whole another can of worms :) Jul 3 '20 at 18:17
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    Actually in the US direct burial needs 24” (60cm). PVC conduit gets 18”. Jul 3 '20 at 19:34
  • Yep, sorry, shot from the hip on that one.
    – JRaef
    Jul 6 '20 at 19:40
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Yeah, you can lay it on the ground like that, but don’t energize it!!!

As far as hokey-doke burying it on a “best effort” basis, you have to check the requirements of your Metric nation’s electrical code, and do what it says.

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    This seems to be more-so a comment than an answer. It’s akin to someone asking the same question in the US and getting an answer of “go check the nec”. Jul 3 '20 at 22:01

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