brucelee
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- Reaction score
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hi everyone
i have a question on a shower circuit the ccu is a crabtree sb6000 type,tn-c-s system,100a main switch split load 6 way 4 protected by 80a 30mA rcd with shower 40a,cooker 32a not used,32a sockets for all house,16a old immersion circuit now used to supply 3 pir 500w halogen floods off two seperate 5a sw/fused spurs, one is controlling 2 floods and the other controlling 1 flood and two lights in loft,on the other side is a 40a 30mA rcd protecting 2 6a light circuits the MCBs are all type 1 crabtree sb6000 except the shower which is a 40A type 2 crabtree 610 10mm cable 4mm cpc 45a pull switch shower 9.5kw at 240v 8.8kw for 230v
my question is about the adibiatic equation concerning cpc which i think is 280a x 280a x 5 sec square root divided by 115 for k value is this correct way of doing this calculationon a bs3871 type2 40A cb, which i get to 5.44 so it should be a 6mm cpc is this correct how ive come to this conclusion
the max zs for a bs3871 type 2 is 0.82ohms the max measured according to gn3 is 0.66 ohms
as this circuit is protected by a 30mA rcd then does this satisfy the regs i have not done any tests yet but i am going to do a ZE,continuity to check ZS,insulation resistance, pfc etc if i find that the measured ZS is larger than the MAX measured ZS should i try to get a type1 to replace the type 2 the type 1 has 160a 5 second type current charicteristic which when doing adibiatic would bring cpc size down to 3.11 so then the 4mm cpc would be acceptable and will also increase max zs to 1.44ohms and max measured value to 1.16 ohms
is this the best thing to do if it doesnt meet the adibiatic and ZS
does anyone know where i can get a crabtree 40a sb6000 type1 bs3871 cb from
any help and advice would be grateful cheers
i have a question on a shower circuit the ccu is a crabtree sb6000 type,tn-c-s system,100a main switch split load 6 way 4 protected by 80a 30mA rcd with shower 40a,cooker 32a not used,32a sockets for all house,16a old immersion circuit now used to supply 3 pir 500w halogen floods off two seperate 5a sw/fused spurs, one is controlling 2 floods and the other controlling 1 flood and two lights in loft,on the other side is a 40a 30mA rcd protecting 2 6a light circuits the MCBs are all type 1 crabtree sb6000 except the shower which is a 40A type 2 crabtree 610 10mm cable 4mm cpc 45a pull switch shower 9.5kw at 240v 8.8kw for 230v
my question is about the adibiatic equation concerning cpc which i think is 280a x 280a x 5 sec square root divided by 115 for k value is this correct way of doing this calculationon a bs3871 type2 40A cb, which i get to 5.44 so it should be a 6mm cpc is this correct how ive come to this conclusion
the max zs for a bs3871 type 2 is 0.82ohms the max measured according to gn3 is 0.66 ohms
as this circuit is protected by a 30mA rcd then does this satisfy the regs i have not done any tests yet but i am going to do a ZE,continuity to check ZS,insulation resistance, pfc etc if i find that the measured ZS is larger than the MAX measured ZS should i try to get a type1 to replace the type 2 the type 1 has 160a 5 second type current charicteristic which when doing adibiatic would bring cpc size down to 3.11 so then the 4mm cpc would be acceptable and will also increase max zs to 1.44ohms and max measured value to 1.16 ohms
is this the best thing to do if it doesnt meet the adibiatic and ZS
does anyone know where i can get a crabtree 40a sb6000 type1 bs3871 cb from
any help and advice would be grateful cheers
