Does armoured cable to Garage need to be buried?

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Roy22

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Bit confused on this one. An electrician has quoted to run a supply to my adjoining garage. The route would be from the external meter box (splitting the heavy supply cable to Consumer Unit), dropping down a foot or so and into a narrow gravel trench running right in front of the house to hide it, then at the opposite corner rising out of the trench and following the perpendicular wall (less visible) and through another wall into the garage.

He says that as it's armoured he need only hide the cable just under the gravel, with no warning tape on top of it.

Elsewhere I've read it should be properly buried to significant depth with warning tape on top. This job is to replace a less legitimate supply to the garage, so I don't want to pay good money for a new job if it doesn't meet the Regs.

Is anyone sure if this is acceptable?
 
Roy22 said:
... He says that as it's armoured he need only hide the cable just under the gravel, with no warning tape on top of it. .... Elsewhere I've read it should be properly buried to significant depth with warning tape on top.
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Armoured cable does not have to be buried.

However, common sense, if not regulations, suggest that if it is not buried at a safe depth, then it probably should not be buried at all (i.e. just left 'visible'), since "just under the gravel" is probably about the worst of all worlds. I can tell you from experience that it IS possible to put a spade through armoured cable!

Others may have different opinions.

Kind Regards, John
 
JohnW2 said:
Armoured cable does not have to be buried.

However, common sense, if not regulations, suggest that if it is not buried at a safe depth, then it probably should not be buried at all (i.e. just left 'visible'), since "just under the gravel" is probably about the worst of all worlds. I can tell you from experience that it IS possible to put a spade through armoured cable!

Others may have different opinions.

Kind Regards, John
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I don't(y)
 
I do not know what the regulations say but I do know that the tines of a garden fork can penetrate the sheath of a SWA cable and displace the strands of steel enough for the tine to make contact with a live conductor.

EDIT I agree with JohnW2
 
Thanks for your replies. I don't have a copy of the Regs, is it possible he might counter that as the gravel trench is just a few inches wide and right against the front of the house 'No one would reasonably dig there?'.

Not defending the guy, just asking. Assuming you are confident this is wrong, would you regard this as a bad guy to hire? He was youngish, pleasant & helpful when called out, had all the kit so not a complete cowboy. I'd have thought younger, newly qualified electricians would be closer to the Regs not ignoring them?
 
I agree with other opinions as above, if it’s going to be buried it does need to be at a sensible depth. And warning tape over it regardless. If the existing gravel trench isn’t wide enough to excavate (hence why he may be going this route) then I would suggest running the armoured through a piece of tube or conduit to give it a big extra protection, but would cover it with warning tape all the same
 
Roy22 said:
Thanks for your replies. I don't have a copy of the Regs, is it possible he might counter that as the gravel trench is just a few inches wide and right against the front of the house 'No one would reasonably dig there?'. ... Not defending the guy, just asking. Assuming you are confident this is wrong, would you regard this as a bad guy to hire? ...
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In terms of the regs, I don't think there is anything 'wrong' with what he has said. As far as the regs are concerned, armoured cable does not need to be buried (although it may be if one wishes), and that's it - it does not say anything explicitly about 'burying at a less-than-ideal depth' - although there are vague 'catch-all' regs (about taking reasonable steps to minimise the risk of mechanical damage etc.).

Rather than anything to do with regs, it's more a matter of common sense. However, given that you now tell us that the gravel is only a few inches wide, it could well be that he would be exercising reasonable common sense by saying "'No one would reasonably dig there". Even in such a place where digging (or 'probing'!) was very unlikely, I would personally probably not contemplate 'shallow burying', but, as I've said, I can see a 'common sense' argument that it would probably be OK.

From what you've told us, I therefore personally see no reason why you should be 'warned off' this guy.

Kind Regards, John
 
I seem to remember it's a frequent C&G Wiring Regs question: (roughly...)

How deep must you bury a cable?
1 1m
2 450mm
3 500mm
4 As deep as it needs to be
 
BS3036 said:
I seem to remember it's a frequent C&G Wiring Regs question: (roughly...)
How deep must you bury a cable?
1 1m .... 2 450mm ... 3 500mm ... 4 As deep as it needs to be
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... and the expected answer was?

Of course, as so often, it would be a pretty bad question, since the correct answer could be "not at any depth" if the cable were not of a type suitable for direct burying!

Kind Regards, John
 
Thanks for your answers. As these are being affected by the gravel width, I've looked more closely at the run in front of the house. Slabs have been laid, and peering behind the bins, not at an even distance all along the front of the house.

Near the meter box there's just a 4 inch gap. Behind the front bins in a partial flowerbed (well, roses grow from it to above the bins) the gap is 13 inches. So someone's unevenly laid slabs allowing for some plant growth probably. I'm guessing most of you will now say this is not a trivial trench, it could later be dug up, so a proper deep/taped cable should be used? If so, would you argue the point with him or look elsewhere?
 
BS3036 said:
I leave this as an exercise for the student...
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I thought you might say that! As I implied, my answer would be the (non-existent) #5 ("not necessarily any of the above") :-)

That's why I've always hated MCQ's - the answer I want to give, and believe to be the correct answer, is often not one of the 'multiple choices' on offer!

Kind Regards, John
 
Roy22 said:
Near the meter box there's just a 4 inch gap. Behind the front bins in a partial flowerbed (well, roses grow from it to above the bins) the gap is 13 inches. So someone's unevenly laid slabs allowing for some plant growth probably. I'm guessing most of you will now say this is not a trivial trench, it could later be dug up, so a proper deep/taped cable should be used? If so, would you argue the point with him or look elsewhere?
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I think you are probably regarding this as too 'black and white', hence your electrician as 'right' or 'wrong'.

As I've said, there is no explicit regulation to be 'right' or 'wrong' about, merely a general requirement that all cables be reasonably protected against mechanical damage. I therefore think that you need to discuss this with yiour electrician and come to a mutually acceptable judgement as to what is 'reasonable'.

As a compromise (if you had difficulty in agreeing on what was 'reasonable'), as has been suggested, if you ran the cable, 'just below the surface of the gravel' through a reasonably thick-walled steel pipe, then I feel sure that would provide more than enough 'mechanical protection'.

Kind Regards, John
 
Roy22 said:
Bit confused on this one. An electrician has quoted to run a supply to my adjoining garage. The route would be from the external meter box (splitting the heavy supply cable to Consumer Unit), dropping down a foot or so and into a narrow gravel trench running right in front of the house to hide it, then at the opposite corner rising out of the trench and following the perpendicular wall (less visible) and through another wall into the garage.
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How is this electrician proposing to fuse down the swa, given you wrote " splitting the heavy supply cable to Consumer Unit"? is there room for a switchfuse in the meter cupboard? Hope he wasn't expecting to just join it directly to the cu tails.
 
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