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I think the undersized cable is a red herring as far as the fault goes. It may be poor - but it can't produce an over-current fault. Suggest you follow Canoeboy's advice and also check the RCD trips. If all checks out OK then it might be worth checking the control panel - there's probably an...

To my mind 537.2 refers to isolation of circuits - so in domestics an MCB is OK 537.3 is switching off for mechanical maintenance - thinking more in terms of lathes, pillar drills or factory type ventilation fans. Once again I can't get excited by using the MCB as an isolation - it's very...

Hadn't seen BS8436 cable before - looks a great idea - but does it actually comply to the BS7671 regs? The aluminium tube offers virtually no resistance to penetration - though it should trip the mcb if live is nicked at the same time.

Of course ac and dc are different - but within the context of cable design it strikes me that DC is considerably easier - no reactance to worry about - no transients - no peak voltages, no phase shifts so ultimately you come down to series and parallel resistance. Canoeboy - what an excellent...

So why would DC cables need to be double insulated? Is this the same argument as meter tails being sheathed/DI? The counter argument for this is SWA is used for submains. On virtually all amplifiers and appliances the 0v dc from the power supply is connected to earth/chassis. If earthing of the...

Sorry Steps - billy basic stuff here - what's DI?

Great idea - thanks

Sorry Mr Newman - I know this isn't where you want the thread to go - but I would like to know why - from the basic physics - a 600vac SWA would not suitable for 800v dc. The peak to peak voltage on a 600vac cable is in the order of 900v - which is what the insulation would need to withstand. If...

Ah - didn't know it went up to 800v - always assumed it was around the 200v mark. That would explain it! Thanks.

I don't do PV so tend to be pretty basic in the way I think about this - but why would it be a hazard to put DC down an SWA cable? My reasoning is as follows:- If the 0v dc line is connected to earth internally at the inverter and an MCB and isolater is at the source end any cable fault would...

It's easy now it's been explained properly!

Rest assured the lecturers find this just as hard! It's the exam boards and colleges that need to review their practices. One re-take per exam per year and off the course on the second failure would go a long way to sorting things out. As it is a number of level 3 students can't do basic...

Band is going well! Hopefully a demo will be on line soon!

Fully agree with this - but from my experience a lot of students on 2330 level 2 and level 3 still have problems with this - particularly when k M or m prefix the unit of measurement. However with multiple choice and multiple retakes an awful lot pass - possibly because all permutations of the...

86-year old lady's letter to bank...... Shown below, is an actual letter that was sent to a bank by an 86 year old woman. The bank manager thought it amusing enough to have it published in the New York Times. Dear Sir: I am writing to thank you for bouncing my check with which I endeavoured...

Yes - you're right Perhaps an air vent would be a better idea!

Was thinking of the wood backing to get the back boxes within 5mm of the floor level - can just imagine some numpty filling the lot up otherwise! I initially thought of the high impact conduit route - but thought that I could get a smooth curve with the flexible so cable could be replaced at a...

Hope you can help me out here - no experience of a job like this ever! I've been asked to quote on a new extension - high end oak framed with lots of glass. The floor is going to be built up as solid, insulation, 100mm concrete block with 75mm screed on top. Piped underfloor heating is going...

Trust is imperative. However trust is a continuous process and with backs against the wall you can be surprised!!! A co-operative sole trader agreement makes good sense.