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Just found that the OSG does have appendix H for Household and similar installations, which shows 2.5mm2 for a ring. However this example question is not a house, its a shop. A PC shop and the ring circuit is in the repair room. No idea if that has any bearing on the matter though!

Thanks guys. I'm still not sure what C&G are getting at, slipping a ring circuit into the question, which is a set of 7 circuits, all radial except one. It's in the form of a grid sheet. The fact that each circuit in the grid has the same sections for filling in the Ib, In, It, CSA etc etc...

Thanks for responding! The question specified 0.8 for the grouping cable factor Cg, 1.0 for the temp factor Ca. 1.0 for Cf. No other factors needed. It also specified method B. The example is t&e in dado trunking. We were told to reference tables F5i and F5ii. Table F6 being for other...

Just started Level 3 C&G and we're doing cable sizing calcs. Using a previous years exam question. We ran through a few examples of radial circuits, all well and good. Following this proceedure: Work out total load on circuit from plan. Work out design current. Ib. Ib<In<It Find suitable...

Sadly not under warranty. Manufactuer folded.

We have some big, heavy double glazed bi folds made from accoya. They are 5 years old and due for some paint but I've noticed the joints have opened up on the frames a little so the door is no longer square. Not sure the technical term for this, but before I paint them, is there a way to get...

All valid points but going by the learning material provided, only ASHP and GSHP are quoted as being "fit and forget". Maintenance is not mentioned on solar thermal, so as 'we' are students and not micro-gen service engineers with years of experience, the answer is ASHP. Except its not...

On my course I'm amazed how little quizing of the students there is by the tutors. No "gather round everyone, look at Fred's install here. What's wrong with it?" or "Can anyone tell me what the difference is between a TT and TNS system?" etc. We just to the worksheet questions... Anyway going...

Yes MCQ is a pretty poor way to assess the state of learning. A proper mix of classroom and practical work, which relates to the classroom work with continual assessment by the tutors would be best. Any tutor can pick up who gets it, who is getting it slowly but surely and who is a lost cause...

So consensus is ASHP is the lowest maintenance. The course notes also say ASHP is a 'fit and forget' system. They don't mention maintenance on solar thermal. Correct answer: Solar thermal. (WTF)

That was my thinking too, but as you and other said there is certainly a possibility of a type C tripping magneticially too, so only type D is going to be the slowest to trip. I mean this chart doesn't really answer the question does it:

OK, I think there are two right answers here... Again, nothnig in the actual course notes on this... You have to pick one, no option to write an essay on how they are all prone to issues after x years... I'd argue that an ASHP and Solar Thermal have similar maintenance requirements. Only...

Yeah, I think the activation of the magnetic trip rather than the thermal is what they are getting at in a cack handed way. Given that we won't have the curves to hand and that the exam is done on a computer so you can't say, its type B and C, I'd go with type B. There are some other...

Any thoughts on this question: Which one of the following devices will disconnect in the fastest time if a short circuit current of approximately 300A occurred on a circuit? a) 32A/30mA Type C RCBO b) 32A Type B circuit breaker c) 32A Type C circuit breaker d) 32A Type D circuit...

Ha ha! Yes, suck it and see. Well I have nothing to lose, but I am going to do as much research as I can before I shut the heating off, at this time of year!

There's a lot to unpack there. I'll get back to you. Thanks for the input though. I have the old and new boiler specs so I can check. I'll check for the bypass. The original system has an external bypass, near where the pump is.

soldering iron for the temp sensor, blow lamp for the original pump! (actually probably some compression fittings!)

Yep, if both run it will be fine, but it's quite a bit of power to waste if its not needed. I'm doing this to save some money on bills after all!

Hi Rob, not been installed yet. I have an old vented Potterton that I want to replace with a new system boiler. In theory I can't see why it can't be done, keeping the system vented (so I don't have to change the tank). Hopefully there's enough head to keep the new boiler happy. If not I'll get...

Thanks Fixit. Just one more thing, given that the new boiler has an integral pump, the exisiting external one can be removed can't it? No point in having both running and wasting leccy.