Bending a supply cable

Without seeing it, the advice has to be 'it is not wise.' Just because it has been done once or twice and nothing went wrong, does not mean it will always be so.


Yes it may be possible to suspend the board from ropes from the ceiling and  swing it forward an inch or two, if there is a long length of cable than can gently curve, but not in the general case.


Or put another way, only proceed, when everyone involved  fully understands and is happy with exactly what process will need to be invoked for each possible bad outcome.

How much arc flash PPE clothing is the plaster intending to wear for example ? I bet it is not even on his RADAR. It should be !


A very credible example of a bad outcome would be if say the cable kinks too sharply instead of a graceful curve,  and the lead sheath cracks at the point where it leaves the floor, or if the backboard is not separable from the wall  in the way expected and it drops at a sharp angle, damaging the cable.  In such a case, once the cable has been damaged, fire or not, given the length and diameter of a joint for that sort of cable,  it probably means digging up the grounds outside to bury a joint, and then routing a new service cable into the building.


Now the 10 mins of plastering starts to look expensive, but at least you get a week or two with the power off to do it.


When PILC is first installed the paper is oily, and that gives the turns of paper the ability to slide over one another, and the  whole cable has a well defined minimum bend radius of a few feet.

The oil also provides a degree of self healing against pinhole failure of the insulation, as it fills any small holes and joints/tears in the paper.

In cellars it is not unknown for the oil to seep out the end, and the reverse is true it that a cable high up may lose some or all of the oil as it drains down, especially with high load cycling making it warm and cold. The upshot is that an old cable is not always as safe to flex as a new one, though it may well be perfectly fine for years if unmoved. There is a reason the DNO cable jointers are a lot more careful than the meter swappers.



In summary there is a very good reason why the wall behind the meter board is often bare block work, or very crummy original plaster. I suggest the customer gets used to the idea, and lets go of the idea of plastering behind it. Fill up to the edges instead.


Mike.

Without seeing it, the advice has to be 'it is not wise.' Just because it has been done once or twice and nothing went wrong, does not mean it will always be so.


Yes it may be possible to suspend the board from ropes from the ceiling and  swing it forward an inch or two, if there is a long length of cable than can gently curve, but not in the general case.


Or put another way, only proceed, when everyone involved  fully understands and is happy with exactly what process will need to be invoked for each possible bad outcome.

How much arc flash PPE clothing is the plaster intending to wear for example ? I bet it is not even on his RADAR. It should be !


A very credible example of a bad outcome would be if say the cable kinks too sharply instead of a graceful curve,  and the lead sheath cracks at the point where it leaves the floor, or if the backboard is not separable from the wall  in the way expected and it drops at a sharp angle, damaging the cable.  In such a case, once the cable has been damaged, fire or not, given the length and diameter of a joint for that sort of cable,  it probably means digging up the grounds outside to bury a joint, and then routing a new service cable into the building.


Now the 10 mins of plastering starts to look expensive, but at least you get a week or two with the power off to do it.


When PILC is first installed the paper is oily, and that gives the turns of paper the ability to slide over one another, and the  whole cable has a well defined minimum bend radius of a few feet.

The oil also provides a degree of self healing against pinhole failure of the insulation, as it fills any small holes and joints/tears in the paper.

In cellars it is not unknown for the oil to seep out the end, and the reverse is true it that a cable high up may lose some or all of the oil as it drains down, especially with high load cycling making it warm and cold. The upshot is that an old cable is not always as safe to flex as a new one, though it may well be perfectly fine for years if unmoved. There is a reason the DNO cable jointers are a lot more careful than the meter swappers.



In summary there is a very good reason why the wall behind the meter board is often bare block work, or very crummy original plaster. I suggest the customer gets used to the idea, and lets go of the idea of plastering behind it. Fill up to the edges instead.


Mike.