Hi,
I'm hoping someone can clear something up for me.
I'm about to install an electric shower in my own house. I previously ran a 10mm cable in when re-wiring but now trying to decide how powerful the shower can be. For the sake of this calculation I'll use a 10.5kw shower.
the cable run consists of roughly: 6 meters under the floor (not insulated)
2.5 meters up 2x2inch trunking with 3 other cables (socket radial, smoke, lighting cables)
8 meters in loft below 100mm insulation
1 meter clipped direct behind tiles/ plaster
so to begin:
10500/230 = 45.7a
MCB should be 50a
Now its the rating factors i'm getting a bit confused with.
I'm assuming ambient temperature is 30 so.....................Ca is 1
Looking at table 4c1 in regs...........................................Cg is 0.65
I cant find any rating factor for the Ci. can only find table 4D5 which says 10mm cable can take 45a for method 100 (under 100mm insulation)
BS60898 mcb being used so no rating factor there?
At this point i'm getting a bit confused with how to work out. Do i actually need to apply a rating factor for Ci???
I know i could probably get away with using a 40a MCB and expect the shower not to exceed 40a but I was hoping to use this job as an assessment for NICEIC DI and would like to justify my actions much as possible.
I know i should know this but never really had the need for cable calcs working for other people all my career! And never was good at it at college either.
thanks
I'm hoping someone can clear something up for me.
I'm about to install an electric shower in my own house. I previously ran a 10mm cable in when re-wiring but now trying to decide how powerful the shower can be. For the sake of this calculation I'll use a 10.5kw shower.
the cable run consists of roughly: 6 meters under the floor (not insulated)
2.5 meters up 2x2inch trunking with 3 other cables (socket radial, smoke, lighting cables)
8 meters in loft below 100mm insulation
1 meter clipped direct behind tiles/ plaster
so to begin:
10500/230 = 45.7a
MCB should be 50a
Now its the rating factors i'm getting a bit confused with.
I'm assuming ambient temperature is 30 so.....................Ca is 1
Looking at table 4c1 in regs...........................................Cg is 0.65
I cant find any rating factor for the Ci. can only find table 4D5 which says 10mm cable can take 45a for method 100 (under 100mm insulation)
BS60898 mcb being used so no rating factor there?
At this point i'm getting a bit confused with how to work out. Do i actually need to apply a rating factor for Ci???
I know i could probably get away with using a 40a MCB and expect the shower not to exceed 40a but I was hoping to use this job as an assessment for NICEIC DI and would like to justify my actions much as possible.
I know i should know this but never really had the need for cable calcs working for other people all my career! And never was good at it at college either.
thanks