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Wouldn't it be nice if life were so simple :D. That will work provided the adiabatic equation is valid for most of the duration of the fault. It does not work outside the limits of the equation - these being 0.1 second at the lower end and 5 seconds at the upper bound. The largest errors...

I raised the question. It originally came about because of some advice given by the Electrical Safety Council (ESC) that suggested that a 'front end' RCD was no longer needed provided all circuits were protected by split bar RCDs or RCBOs. There is nothing wrong with this in principle, but...

Basically that the HSE accept that 'working on or near live conductors' includes testing. They also accept that some testing can only be carried out with when the equipment is live. However, the assessment and precautions required by Regulation 14 still apply. So looking at each...

I think you should read Regulation 14 again. Then read the Memorandum of Guidance for the EWR - either version. Start with paragraph 8 in the first version, or paragraph 208 onwards in the new version. Then review your safe isolation procedures (which ever one you use). You will find that...

It depends what you mean by very old. BS3036 came into force in 1958. New standards usually indicate what, if anything, they are replacing but I cannot find any reference to an earlier standard in BS 3036. So it is possible that fuses made before 1958 do not meet any particular national...

Good idea - but I think that it would have to be welding. Solder might cause corrosion and is not a particular good method for joining steel. Crimping is probably not practicable on the conduits currently available. Now if you weld you will damage the protective coating so you would need to...

Well BSI and the IET invite comments so be a good chap and talk to them.

BAS I am not interested in your ridiculous attempts to justify the assertion that conduit couplers need to be accessible for inspection - even when they are cast into a concrete screed or are plastered into a wall. There are probably hundreds of thousands, or maybe millions, installed in...

A coupler is part of the conduit system - one is supplied with each length of conduit. Cable is not supplied as part of a junction box. A coupler is used to form an electrical joint that is part of the equipment and is therefore covered by [526.3 (v)]. Well read what is written then.

I didn't write the regulation BAS - take it up with JPEL/64. I am not trying to interpret it such that it would encompass joints, such as those made using conduit couplers, that it was never intended to apply to - are you? As you well know, these regulations are written by engineers...

RF lighting Well lets review the situation :D. If I have understood your example correctly you are using a short length of conduit, earthed via the surface mounted box. This conduit is partly flush in the wall and as such comes with the scope of [522.6.6]. The purpose of the conduit...

There is nothing wrong with cheap provided you can live with its limitations. I mentioned harmonics, and as you no doubt know, these will be present in any distorted wave. A square wave can be 'created' by adding together as many odd harmonics, increasing in frequency, as possible. This...

First take a look at this: http://www.cfmeu-construction-nsw.com.au/pdf/sabaninverters.pdf. To answer your question - its most likely that electronic equipment may have some trouble with the harmonics in a distorted sine wave. So thats most appliances these days then :D. Resistive loads...

That depends how you interpret it - the words are not precise. What is 'the appropriate product standard'? [526.3 (v)] does not state that the actual connection has to comply with some standard - just that the equipment should. Cable is electrical equipment but the cable standards only...

Depends on the type - those used in a commercial office normally do enclose the plug and protect it. This type do not: http://www.tlc-direct.co.uk/Main_Index/Wiring_Accessories_Menu_Index/Chelsea_Floor_Sockets/index.html

So all those installations in cast concrete structures are in breach of the regulations are they :shock: If you have trouble accepting that this is clearly not the case - then you could apply a major UK Lighting manufacturer's defence - not named because they might decide to sue me :D...

I do not disagree that, according to BS 7671, flexible or pliable conduit cannot be used used as a protective conductor [543.2.1]. The basis for this is that these containment systems can, and all to often do, fail when subjected to mechanical stress. A common mode of failure is that the...

Oh yes you must comply - think of the consequences if you don't. The world may end - it could be worse than global warming :D. Or you could look at Approved Document M section 4.25 and decide that the exception mentioned there for floor boxes in open plan offices might just be applicable in...

A number of people have viewed this post and some may not be familiar with this problem so I will try to give a simplified explanation. Let's start with a example of a simple system - a battery with a length of cable connected to it that has a resistance of 0.5 ohm for the line and 0.5 ohm...

I have not expanded the graph ricicle has posted but if you do you will see that at 40 kA you are in the region below 0.01 second and no data is given. This is because current time graphs are not much good at this level and you need to use Let Through Energy data - as I stated above. Let...