Armoured cable depth

[Delboybully]

I got called to look at a job for a landscape company, one of the chaps who works there is a mate who recommended me. It would be a good contact to get some regular work especially as they dont have a regular spark.

The customer wanted to have an external socket to run a water feature. The company forgot to arrange for this socket to be installed and now the patio is in place. So they have dug a 4inch trench in the path to the side of the house, the path is around 2.5ft wide. The cable will run from the house, under the path and then onwards to the socket position through flower beds. I told the customer the trench isnt deep enough. Then the boss of the landscape company turned up and when I told him it needs to be deeper, he said 'thats ridiculus, its in concrete'. I told him I am not doing it and he best get someone else to do it to which he replied that he would. I then left.

The mate who recommended me said he would put the cable in and would I connect it up to which I replied no.

I usually insist on armoured cable to be installed to a depth of 18 to 24 inches depending on where it is. What do others do?

Also what would you do in the case above? Would you accept 4inches in concrete?

 

[Hellmooth]

I've just been looking through armoured depths lol that's quite spooky to come back on and see this post!

Ive been asked to run power at my golf club and was looking it up, there isn't any reg that specifies a depth, it's more a common sense situation, making sure that it's deep enough not to get damaged or affected by day to day activities, I'd say a minimum of 3-400mm anyway!

As for being in concrete, if it was in ducting in the concrete and you could see the cable at both ends entering and exiting the ducting then I would possibly be ok with it!

 

[Marvo]

We usually go 500-600mm deep but if it's in concrete or under paving it shouldn't be a problem at any depth because it's not likely to get damaged.

 

[Hellmooth]

How long is the run? Rcd protection?

 

[ruston]

The consideration is the 'future disturbance of the ground'. With permanent markers and identified on the diagrams you have a bit of leeway.

 

[Delboybully]

Marvo, I see your point it is unlikely to get damaged in normal everyday use, I am thinking of the poor sod who gets the job of removing the concrete path when someone wants it changed to something better looking. Any warning tape isnt going to give much warning to a SDS max or kangoo.

The circuit does have RCD protection.

 

[ruston]

Tiles or metal markers can be used too, other than tape.

http://www.eliteprecast.co.uk/service-protection/concrete-cable-protection-covers/

 

[Leesparkykent]

I wouldn't have a problem with it being in a duct at that depth with concrete covering it.

 

[Marvo]

Marvo, I see your point it is unlikely to get damaged in normal everyday use, I am thinking of the poor sod who gets the job of removing the concrete path when someone wants it changed to something better looking. Any warning tape isnt going to give much warning to a SDS max or kangoo.

The circuit does have RCD protection.

I think there's always a 'what if' scenario for any depth it's buried, if he wants a fish pond and gets a back-hoe in to dig a hole then 600mm also won't cut mustard. Especially if there's RCD protection and given that SWA can even be run surface so I'd say the depth required is down to common sense as to likelihood of general accidental damage. Determination of this via a quick risk assessment would be fine for me personally.

 

[Andy78]

I'd not be worrying too much if under concrete. I would still be marking it though.
I wouldn't be keen for it to be buried direct in the concrete though. I would like to dig it a bit deeper than has been stated the trench already is, bed it on sand, then cover it with sand to provide a bit of leeway from sheath punctures when the concrete goes down.

Reg 522.8.10 is the one you need...... 600mm is the generally accepted depth in easily dug ground to satisfy this reg, however your concrete is not forseeably easily disturbed.

 

[Hawk]

I would have done it. 1. It's buried under concrete and 2. It's rcd protected. Not an ideal depth but it probably would have guaranteed you more work.

 

[davesparks]

I would have done it. 1. It's buried under concrete and 2. It's rcd protected. Not an ideal depth but it probably would have guaranteed you more work.

What has RCD protection got to do with it?

 

[SS-2015]

Get it in, get it covered and get paid!
It'll be fine at that depth.

 

[Delboybully]

I think there's always a 'what if' scenario for any depth it's buried, if he wants a fish pond and gets a back-hoe in to dig a hole then 600mm also won't cut mustard. Especially if there's RCD protection and given that SWA can even be run surface so I'd say the depth required is down to common sense as to likelihood of general accidental damage. Determination of this via a quick risk assessment would be fine for me personally.

This doesnt make sense to me.

So a cable is buried 600mm deep with some warning tape at 300mm deep. Whoever is digging out this pond will get plenty of warning that there is a cable below, bingo, the digger will be more careful.

In the job I walked away from it was 4 inches deep. It is perfectly reasonable, that with power tools to break the path out, that the digger could go through the warning tape and hit the cable in one go,therefore the warning tape could be of little use. This is why I walked from the job!

Surface run SWA is ok because you can see it, and again be careful around it. The danger is when SWA is shallow and then a digger gets no warning!

Thats my thinking anyway!

 

[davesparks]

A concrete slab is good protection against all normal and reasonable use of the land.
Smashing up the concrete is not a normal use of the ground. It is also reasonable to expect anyone doing so to make efforts to identify the presence and location of any buried services.
And ultimately if it is damaged then the armour will do its job as intended (assuming you have done yours correctly in sizing the cable and providing fault protection)

 

[Marvo]

I'm also with Dave, I just think that you're being unnecessarily cautious by trying to cater for a scenario that should never reasonably happen. Just my thinking and others may disagree.

 

[ruston]

And I would think if it is a water feature it will be clearly visible or obvious that it has an electrical supply.

 

[Delboybully]

It is also reasonable to expect anyone doing so to make efforts to identify the presence and location of any buried services.

Some of the landscape gardeners I have met are not that smart!!!!

It seems to me that this one is down to an indivual sparks opinion!

 

[Octopus]

This old chestnut. The regs are conspicuous by the lack of "proper" recommendations and it's about time this was sorted.

I have run swa under flag stones, and will do it again.

the last landscaper I encountered on a job asked why I was wasting the clients money using swa rather than flex!

 

[bf03yvd]

Could I suggest trunking ? How many likes will I get for this ?