insulation test, RCDs & calculatong load?

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biggals

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hello there everyone.. just become a member only recently so bare with me if i'm all over the shop!.. just becoming new to this domestic installers game also so will probably post a few daft questions along the way...

first thing is that i've changed over a cu from and a BS3036 fuse board to a new split board and added a few extra circuits.. 2x 32A for ring and cooker.. so now on the 30mA 80A RCD i've got 3x32Amp MCBs... is that ok considering its says 80amp and will diversity allow it?

also, the main question is that i've tested all the circuits and the downstairs ring sockets have an insulation problem.. looks like a break through the cable somewhere.. i've literally spent about 14 hrs yesterday walking around changing and investigating all the outlets but cannot find where its at!! problem is most of the wiring is hidden and behind kitchen units etc. so don't want to start pulling the fellas house apart! (any more than i've done).. is there a way of finding out the area where its at or an i missing a trick of the trade?? was alot easier in training when all the wiring was surface mounted and open.

PLease please help if you can cos i've gotta go back there sunday and sort it!!!! aaaaagh... thanks

also... (probably a few more daft ones for you) why does the spliy baord come with a 63A 30m RCD and an 80A 30m RCD when the main fuse is 100A..? is it just the board i got?, and that it caters for houses with 60A / 80A incoming fuses..?

also, i've studied up so many times on the total load calculating but still seem to struggle on it... for the total load on the whole installation do i add up all the mcb ratings and use the diversity factors?, and for say a lighting circuit do i add up all the luminaire power wattage for cable/ breaker sizing etc.. How can you calculate the total load on a ring circuit even before anythings plugged in.. i think i need an example of a circuit or someone to tell me in really basic terms... (or probably just a slap!!)....

please help is you can cos i'm doing these for my installers practical and don't wanna struggle if the inspector asks me about these.... Thanks

 
hello there everyone.. just become a member only recently so bare with me if i'm all over the shop!.. just becoming new to this domestic installers game also so will probably post a few daft questions along the way...first thing is that i've changed over a cu from and a BS3036 fuse board to a new split board and added a few extra circuits.. 2x 32A for ring and cooker.. so now on the 30mA 80A RCD i've got 3x32Amp MCBs... is that ok considering its says 80amp and will diversity allow it?

nothing wrong with what you have said. standard dual split will fit just about every house, unles they have electric heating or other high loads etc, then you may need something bigger

also, the main question is that i've tested all the circuits and the downstairs ring sockets have an insulation problem.. looks like a break through the cable somewhere.. i've literally spent about 14 hrs yesterday walking around changing and investigating all the outlets but cannot find where its at!! problem is most of the wiring is hidden and behind kitchen units etc. so don't want to start pulling the fellas house apart! (any more than i've done).. is there a way of finding out the area where its at or an i missing a trick of the trade?? was alot easier in training when all the wiring was surface mounted and open.

break the ring at CU and a random socket somewhere in the middle - see which half has fault. then take another socket off about half way, and see which half has fault, until you know which cable it is

PLease please help if you can cos i've gotta go back there sunday and sort it!!!! aaaaagh... thanks

also... (probably a few more daft ones for you) why does the spliy baord come with a 63A 30m RCD and an 80A 30m RCD when the main fuse is 100A..? is it just the board i got?, and that it caters for houses with 60A / 80A incoming fuses..?

just the way they come. rarely a problem in a house

also, i've studied up so many times on the total load calculating but still seem to struggle on it... for the total load on the whole installation do i add up all the mcb ratings and use the diversity factors?, and for say a lighting circuit do i add up all the luminaire power wattage for cable/ breaker sizing etc.. How can you calculate the total load on a ring circuit even before anythings plugged in.. i think i need an example of a circuit or someone to tell me in really basic terms... (or probably just a slap!!)....

please help is you can cos i'm doing these for my installers practical and don't wanna struggle if the inspector asks me about these.... Thanks

there have been a few threads about this recently - have a quick search
my red

 
thanks Andy... I'll give that a go sunday... hope it does the trick.. thanks

 

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