Hi Incognito,
Welcome to the forum, you are going to learn lots on here!
Don't get carried away with all the calculation stuffy, real 'sparks' don't do that, its just confusing you and misleading you from what's really simple -- just follow the electrical regulations as you read them. You probably havent got a copy BS7671 yet so I can understand your confused. If you do get a copy have a good read, you'll learn loads about everything and there great for bedtime reading as well. Send you to sleep real quick. Infact when you get a copy quote the regulations to the customer if its a "chicky", she'll be really impressed with your electrical knowledge.
What you need to do here is just apply loads of thin "green'n'yellow" looking wiring (let you in on a trade secret, thats what they call supplementary bonding wire) to every little bit of metal you can see anywhere in the flat, can't go wrong then -- also guaranteed to impress your assessor too when you apply to join an approved Part 'P scheme' later! And don't worry about the plastic pipes, someone once told a friend of mines girlfriends uncle that the water inside it makes it like a metal pipe anyway. You will pick up more of this knowledge as you spend more time on the forum, dont worry if its all a bit too much for you to at the moment, you will understand it eventually.
And forget about all this main bonding stuff, you dont sound as if you're ready for that yet. What it does is definately overrated and so yesterday, RCD's are where it's at now! Anyways, just to give you a little bit of information as knowledge is power, it's just thicker "green'n'yellow" looking wire but doesn't do anything. Just costs you loads to put it onto the gas boiler pipes and the toilet pipes -- I reckon it should be a plumbers job anyway as those guys know so much more than 'sparkies'. You'll learn more about bonding stuffy type things from the more experienced 'sparks' on the forum as you progress throught your 5W course. I think they're great and I'm wanting to have some of their babies.
p.s. I think you might be better of in the electrical trainee part of the forum to start off, or even the DIY forum if you're still unsure of things. But the guys on here are great and will always help you out if they can ;-)
p.p.s. And keep away from that Geordie fella. You dont want to know what he thinks bonding is for ...... someone reckons whips and chains excite him.
