OP
- Reaction score
- 314
One flaw in BS7671 compared with NEC is the lack of mention of fill ratio - i.e. 2 conductors in 20mm conduit has a much higher fill ratio and therefore less free air to dissapate said heat than 2 conductors in 25mm conduit etc...
Book is getting dumbed down bigstyle with worst case scenarios being treated as gospel rather than realistic scenarios...
Physics might not change but the figures given for the cables are lower than what they can carry (else half the street would going up in flames as the DNO cables ignite.....according to BS7671 those cables are all overloaded...)
Whats the actual sustained load on the circuit going to be..will that load be sustained long enough in all likelihood to cause a risk.
Anyone like to state how many circuits are running at 100% load constantly? (Without even mentioning the heavy derating that BS7671 applies to CCA as a safety margin - 30C ambient rating is a joke, never yet been in a british house that was hitting 30C 18-23C, lower still up here in Scotland or Yorkshire
)
Apologies if this comes across as cranky rather than debatory lucien, my head is pouding, feeling like death warmed up and the more I read, the more it seems that Euro regs are written to the point of making a joke out of the cable sizes...the usual nanny state rather than trusting sparks to make the right call on cable sizing and giving them (and expecting those entering the industry to use) the mathematical equations to work it out, instead we get treated like idiot savants and told to slavishly follow a set of charts that often has no bearing to reality...nor to cables that are smaller CSA by a sizeable margin than the tables are requiring that have been carrying a load as big or bigger for donkeys years and yet have no sign of thermal damage, IR test out ok - yet they are condemned because someone thinks we live in the subtropics, with ambient temperatures hotter indoors than the average Spanish home, drowning in insulation and with every circuit running flat out 24/7/365 - Then happily let 2.2Kw Kettles be sold with 0.75 or thinner flex on a 13A fused plug, ditto for hair dryers, straighteners etc...all of which are far more likely fire risks...especially with the massive amount of counterfeit cheapenese flex on the market....
Oh dear lord...I'm turning into Eng54... :lol:
Book is getting dumbed down bigstyle with worst case scenarios being treated as gospel rather than realistic scenarios...
Physics might not change but the figures given for the cables are lower than what they can carry (else half the street would going up in flames as the DNO cables ignite.....according to BS7671 those cables are all overloaded...)
Whats the actual sustained load on the circuit going to be..will that load be sustained long enough in all likelihood to cause a risk.
Anyone like to state how many circuits are running at 100% load constantly? (Without even mentioning the heavy derating that BS7671 applies to CCA as a safety margin - 30C ambient rating is a joke, never yet been in a british house that was hitting 30C 18-23C, lower still up here in Scotland or Yorkshire
)Apologies if this comes across as cranky rather than debatory lucien, my head is pouding, feeling like death warmed up and the more I read, the more it seems that Euro regs are written to the point of making a joke out of the cable sizes...the usual nanny state rather than trusting sparks to make the right call on cable sizing and giving them (and expecting those entering the industry to use) the mathematical equations to work it out, instead we get treated like idiot savants and told to slavishly follow a set of charts that often has no bearing to reality...nor to cables that are smaller CSA by a sizeable margin than the tables are requiring that have been carrying a load as big or bigger for donkeys years and yet have no sign of thermal damage, IR test out ok - yet they are condemned because someone thinks we live in the subtropics, with ambient temperatures hotter indoors than the average Spanish home, drowning in insulation and with every circuit running flat out 24/7/365 - Then happily let 2.2Kw Kettles be sold with 0.75 or thinner flex on a 13A fused plug, ditto for hair dryers, straighteners etc...all of which are far more likely fire risks...especially with the massive amount of counterfeit cheapenese flex on the market....
Oh dear lord...I'm turning into Eng54... :lol:
