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UK Regs - Underground Cable

B

BIGEYE

Jan 1, 1970
0
Is there any requirements for the laying of underground cables (600/1000V
SWA), for them to be laid on a bed of sand within a cable trench.
Also, is it at requirement that underground cables need to be marked with
cable marking tape or slabs laid above the cable in the trench, before
backfilling.
TIA
 
S

SQLit

Jan 1, 1970
0
BIGEYE said:
Is there any requirements for the laying of underground cables (600/1000V
SWA), for them to be laid on a bed of sand within a cable trench.
Also, is it at requirement that underground cables need to be marked with
cable marking tape or slabs laid above the cable in the trench, before
backfilling.
TIA

I always lay direct bury cables on a bed of sand unless the dirt is 100%
clear of rocks and debris.

The marking tape especially one with a wire in it for exact locating is
always a good idea.

Some engineers require a concrete cap above direct bury cables, 12 inches
below grade. Some even want the cables encased in red concrete.

As specific requirements in the UK, I do not know mate. All of what you
suggest is good practice.

As for my personal preference everything should be in conduit and in
separate trenches. Random lay is a bitch to repair...
 
B

BIGEYE

Jan 1, 1970
0
Thanks for the reply, but need to know if there is any specific requirement,
especially as regards the marking.
 
C

Chris Oates

Jan 1, 1970
0
BIGEYE said:
Thanks for the reply, but need to know if there is any specific requirement,
especially as regards the marking.

section 7.14.1
all cables should be buried to a depth of at least
450 mm with a route marker tape at 150 mm.

sand is a given
 
B

BIGEYE

Jan 1, 1970
0
Is this the 16th Edition Regs?
Thanks

Chris Oates said:
section 7.14.1
all cables should be buried to a depth of at least
450 mm with a route marker tape at 150 mm.

sand is a given
 
N

Neil Swanson

Jan 1, 1970
0
Current UK Regs, Not 16th Edition, but LAW, dictated that all buried cales
should have marker tape (or tiles) 150mm above, on top of the sand. This
includes provate property, say a small supply at 240 to a shed or fountain
would require. Cables in Ducts are different, and do NOT require sand. The
duct I believe precludes the marker, but it can still be used.

The law is not retrospective, but any older cables exposed MUST be marked
during reinstatement process.

At EHV 132kV and above, you will also find lampost markers and tombstones at
boundary crossings.

Hope that helps. You should see what I have had to do in my garden
 
B

BIGEYE

Jan 1, 1970
0
I have looked on HMSO website at Electricity Supply Regs & Electricity at
work regs and cant find any reference to the marking of buried LV cable.
Sorry to be persistent, but do you have the reg number?
Thanks
 
J

Jb

Jan 1, 1970
0
There is NO requiremnent for utilities to mark LV cable, the 16th Ed does
not apply to them and there isn't even a legal depth although you won't have
much of a defence if you lay it 2" down and someone is injured.
As has been suggested elsewhere in this thread it's good practice if you
choose to do it

Jb
 
B

BIGEYE

Jan 1, 1970
0
The LV cable installation has been done on one of our sites as a supply to a
distribution board. It is not a supply from the REC.
The cable has not been marked, and buried direct in a trench where there are
quite a lot of stones.
The installation was overseen by one of our (know-it-all) engineers - AN ICA
ENGINEER. The cable was installed by contractors that happen to be his
mates.
He has been quick in the past to put down other peoples installations and in
the end he has been proven wrong.
I say that this installation is unacceptable and in breach of regulations. I
need some ammo and be sure I am right before I go shouting my mouth off.
So all the help I can get would be appreciated.
Thanks guys.
 
C

Chris Oates

Jan 1, 1970
0
BIGEYE said:
The LV cable installation has been done on one of our sites as a supply to a
distribution board. It is not a supply from the REC.
The cable has not been marked, and buried direct in a trench where there are
quite a lot of stones.
The installation was overseen by one of our (know-it-all) engineers - AN ICA
ENGINEER. The cable was installed by contractors that happen to be his
mates.
He has been quick in the past to put down other peoples installations and in
the end he has been proven wrong.
I say that this installation is unacceptable and in breach of regulations. I
need some ammo and be sure I am right before I go shouting my mouth off.
So all the help I can get would be appreciated.

You could get Health & Safety involved to confirm your opinion
(and most of ours) - they don't even care about Regs

We had a 95mm incoming cut by a JCB - laid by the PoCo
so not marked - some tape a good distance above the cable would
probably have avoided it.

Incidentaly the cutters (water board) tried to avoid compensation
by quoting the PoCo's small print that you are not entitled to an
uninterupted supply.
 
J

John Gilmer

Jan 1, 1970
0
BIGEYE said:
Is there any requirements for the laying of underground cables (600/1000V
SWA), for them to be laid on a bed of sand within a cable trench.

The "wave of the future" in underground wiring seems to be "directional
drilling." (I am talking from certain knowledge of Virginia, USA)

A few months ago the utility installed a brand new underground "drop." The
length was 440'. The contractor started a few feet away from the
transformer pad with a 18" deep trench. The drill machine was guided by a
guy with a special sensor and a walkie/talkie to the operator. Basically,
he "walked" the drill string from the transformer trench to about 18" from
where the conduit to the meter base was. They tied the cable to the drill
string and started pulling the new wires (with some mishaps like the wires
slipping out, but that's another story.

Basically, there is NO special protection of this cable. No sand, no
"warning tape" no nothing.

AND the new run had a failure a month or so after it was installed.
 
J

John Gilmer

Jan 1, 1970
0
I watched a crew doing drilling like that once for a gas line. It popped
out of the ground on them about 2/3 of the way to the destination, and
about 4 meters off to the side. They apparently hit some obstruction that
went undetected. So much of the special sensors (though I didn't notice
if these guys did anything like that, nor did I see their advance surveys,
if they even did any).

I think the guy "walking" the line got a little lazy. In our case, there
was one "blowout" when the drilling mud came up to the surface. They just
backed off a few feet and changed the heading.

(For the curious: the drilling bit has a slant so it wants to go off in one
direction. To go staight, they just rotate the string while pumping mud
and pushing the string.)

A few years ago I watched a crew put a telephone cable under a paved street.
They had a similar drilling rig except there was to mud and no direction
control. To "catch" the string on the other side of the road they ended up
with a 10' deep trench. I stopped watching because I didn't want to take a
chance of being a witness to a man being buried alive.
 
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