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Electrical Question. Consumer Unit.

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Evenin' All,

                       it was fun getting to work today. Firstly, I had left my van's windows open about 5mm at the top to reduce condensation buildup. A Big mistake. The dusty fine snow had found a way in and covered the driver's seat and the steering column and some parts of the dashboard. Joy and bliss I said.


Anyway now to the question. Sparky Sid was installing a new Niglon R.C.B.O. populated consumer unit. It has a main D.P. switch and six R.C.B.O.s.


He always uses one  short length of P.V.C. earth sleeving when assembling these types of consumer units.


Why?


Z.
Parents
  • 0
    O.K. to ease the misery.


    Answer. When we install R.C.B.O.s or M.C.B.s with the new modern cage type terminals and a bus-bar below we have to ensure initially that the cages are fully open to ensure correct bus-bar grip by the cage terminal. If we are not careful we can find a bus-bar finger just in "fortuitous contact" with a terminal and not correctly gripped. I found that on a 40 Amp shower circuit M.C.B. once, but amazingly it was tightly held by chance and no overheating was evident. But overheating could occur if the bus-bar finger is not firmly gripped.


    So we unscrew the M.C.B. or R.C.B.O's terminals fully before trying to correctly fit the new bus-bar from below. Some sparks then push the screws in to ensure that the cage terminal is fully open. If we use a screwdriver that is magnetic it can pull on the screw and close the cage terminal slightly thus defeating the operation. If we use a short piece of P.V.C. earth sleeving to push the screws, being none magnetic, it is more reliable, and unlike a copper wire will not stab our fingers.


    Z.
Reply
  • 0
    O.K. to ease the misery.


    Answer. When we install R.C.B.O.s or M.C.B.s with the new modern cage type terminals and a bus-bar below we have to ensure initially that the cages are fully open to ensure correct bus-bar grip by the cage terminal. If we are not careful we can find a bus-bar finger just in "fortuitous contact" with a terminal and not correctly gripped. I found that on a 40 Amp shower circuit M.C.B. once, but amazingly it was tightly held by chance and no overheating was evident. But overheating could occur if the bus-bar finger is not firmly gripped.


    So we unscrew the M.C.B. or R.C.B.O's terminals fully before trying to correctly fit the new bus-bar from below. Some sparks then push the screws in to ensure that the cage terminal is fully open. If we use a screwdriver that is magnetic it can pull on the screw and close the cage terminal slightly thus defeating the operation. If we use a short piece of P.V.C. earth sleeving to push the screws, being none magnetic, it is more reliable, and unlike a copper wire will not stab our fingers.


    Z.
Children
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