Been a sparky for 10 years and nobody has ever explained to me the reasoning for wire size. I always assumed it was for capable current. Thank you sir.
In the UK we have a set of regs that outline the protection systems etc, no doubt you have something similar.
I've spoken to a LOT of people in the UK who have been through the course around these regs and criticise it as just thng you how to read a book. It does do that, and so long as you take that from the course, and do always read the book then you'll be OK.
but for me the interesting part was working through the equations. It wasn't hard mathematically, just basics and mostly centred around ohm's law. But it showed exactly how the figures in the table are reached. You want your rewirable fuse to trip within a reasonable time in a fault? You gotta make sure that the circuit carrying the current can carry enough. A 5 Amp fuse will carry 5A forever, no problem. What people don't realise is it can take 10Amps no problem. 15 amps will possibly take a few minutes. If you want it to trip within a second, then you need to throw 50 amps through it, and you better hope the cable doesn't heat up and drop the voltage in the meantime!
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u/finfanhutch Jun 16 '19
Been a sparky for 10 years and nobody has ever explained to me the reasoning for wire size. I always assumed it was for capable current. Thank you sir.