Guidance on sizing cable ducts for LV armoured cables

A single  cable in one pipe the width of a driveway sounds quite tame. Even so, put something like a length of poly rope through the duct while straight before you bend it into position - as Dave comments the pulling forces can stack up quiet fast and pulling is easier then pushing.  (I have seen cables that had to be pulled in by forklift truck and it is not pretty sight.)

Sometimes duct is supplied with cord inside, - you can use it to pull in something bigger.

Even then the yellow greasy stuff is worth applying with a rag as the cable goes in (example)  Do not pull the rag in !! Note also you will get nothing like the bend radius from the cable you would be able to do if you were laying it in ,all bends need to be very gently swept. (if it is a single width domestic gate of a metre or so, it will end up being all bends and no flat section pretty much if you have no access holes.)

35 or 50mm ID duct and a cables of ~ 18-20mm OD is  about right for a moderately comfortable straight run. If the cable is more like 25-30 mm OD, then go up  a pipe size. Larger duct never hurt as much as too small. ;-)

I think that website you linked to uses a 40% CSA fill  and that should be for straight run ducts with access pits.

Mike.

A single  cable in one pipe the width of a driveway sounds quite tame. Even so, put something like a length of poly rope through the duct while straight before you bend it into position - as Dave comments the pulling forces can stack up quiet fast and pulling is easier then pushing.  (I have seen cables that had to be pulled in by forklift truck and it is not pretty sight.)

Sometimes duct is supplied with cord inside, - you can use it to pull in something bigger.

Even then the yellow greasy stuff is worth applying with a rag as the cable goes in (example)  Do not pull the rag in !! Note also you will get nothing like the bend radius from the cable you would be able to do if you were laying it in ,all bends need to be very gently swept. (if it is a single width domestic gate of a metre or so, it will end up being all bends and no flat section pretty much if you have no access holes.)

35 or 50mm ID duct and a cables of ~ 18-20mm OD is  about right for a moderately comfortable straight run. If the cable is more like 25-30 mm OD, then go up  a pipe size. Larger duct never hurt as much as too small. ;-)

I think that website you linked to uses a 40% CSA fill  and that should be for straight run ducts with access pits.

Mike.