Wrong-value fuse with British cloverleaf cord
Posted: May 24th, 2014, 6:41 pmI actually have a bunch of cords with British and European plug types in my collection/stash — one of which catches my attention:
It's a cord about 3m long built with H03VV-F (light duty round cable) with 0.75mm² conductors, with a BS 1363 plug and an IEC60320 C5 socket (as commonly used with notebook computers and nicknamed "cloverleaf"). Longwell made it (and quite a few other cables I have, both power and signal). Doesn't sound too bad, right?
The problem with it is that the fuse that came with it is the wrong size for the cord. The C5/C6 socket/inlet couple (along with the double-insulated C7/C8 and ultra-rare, obsolete class 0 C3/C4) can handle just 2.5A, and 0.75mm² cable is good to either 6A or 7.5A depending on who you ask (and the formula I use myself {CSA^0.75, which is based on the fact that quadrupling the cross-section only doubles the diameter [and allowable heating by extension] and appears accurate compared to "official" values given for cables over quite a wide range of sizes} to derive ampacity using a single reference value, in this case 10A through 1.0mm², gives just over 8A for 0.75mm²). But the fuse included with it is a 13A type. Not that this is worse than the situation in the rest of the world (including here in Australia, but excluding North America for the purpose of this statement), where 16A circuit breakers are usually used (thus making it possible for a 0.75mm² cable to get 4× hotter than permissible without tripping the circuit protection) with unfused plugs, but it's not as safe as it should be. Had it been a counterfeit I would have mentioned it here, but I'm pretty sure this one's the real thing. So what gives?
It's a cord about 3m long built with H03VV-F (light duty round cable) with 0.75mm² conductors, with a BS 1363 plug and an IEC60320 C5 socket (as commonly used with notebook computers and nicknamed "cloverleaf"). Longwell made it (and quite a few other cables I have, both power and signal). Doesn't sound too bad, right?
The problem with it is that the fuse that came with it is the wrong size for the cord. The C5/C6 socket/inlet couple (along with the double-insulated C7/C8 and ultra-rare, obsolete class 0 C3/C4) can handle just 2.5A, and 0.75mm² cable is good to either 6A or 7.5A depending on who you ask (and the formula I use myself {CSA^0.75, which is based on the fact that quadrupling the cross-section only doubles the diameter [and allowable heating by extension] and appears accurate compared to "official" values given for cables over quite a wide range of sizes} to derive ampacity using a single reference value, in this case 10A through 1.0mm², gives just over 8A for 0.75mm²). But the fuse included with it is a 13A type. Not that this is worse than the situation in the rest of the world (including here in Australia, but excluding North America for the purpose of this statement), where 16A circuit breakers are usually used (thus making it possible for a 0.75mm² cable to get 4× hotter than permissible without tripping the circuit protection) with unfused plugs, but it's not as safe as it should be. Had it been a counterfeit I would have mentioned it here, but I'm pretty sure this one's the real thing. So what gives?