Webinar, certainly interesting to hear how systems differ over there, already in my head I've got Paul Meenan thrashing out a street fighter style video putting BS7671 against its international cousins.....which is a Flawless Victory? Which has the most Fatalities? Only one way to find out........beg and plead for it to happen 😂 🙏🙏🙏🙏🙏

Interesting webinar. Really enjoyed it. I look forward to the next one on cathodic building structures

Great press. We should get rid of the expression electrical currents tend to take the path of least resistance. Electricity take all and any paths to make its way back to the source. Clearly in the person example you showed with the kettle there could have been small current diverted both in conductive and non conductive mediums metal, wood plastics and not just the individual, in many cases people wearing certain clothes, footwear or the way they are exposed to electrical currents may either help or put in danger their lives. Clearly their resistance or impedance will reflect various factors from the nature of the material and environmental factors as well humidity, temperature etc. Of course you try to then correctly highlight the need for equipotential bonding to address these multiple paths. This all any any paths is much more clear in a situation of a lightning strike on a home where the entirety of the house and any and all its material will become live with that level of very high voltage many of those materials then heat up to catch fire or even explode.

Lump in my throat when you said a good friend of mine…

Leakage currents (~1:08:00) can come from the all the radio frequency filters for Electromagnetic Compatibility (EMC). The typical value in modern electronic filters (consumer equipment) is limited to 1.6mA per filter, but larger industrial equipment can have much larger filter leakage. Typically the EMC idea is that both the line and neutral wire can act as aerials at RF, so if we (at RF) create anti-phase RF signals in those wires, relative to earth, then the emissions will cancel. To create that RF balance the 'Y' capacitor is used, and the RF half supply voltage is isolated from the supply by the line inductors within the RFI/EMC filter. Therefore the key leakage is via one side of the Y capacitor at line voltage, and tail of the Y at earth connection. These leakages are separate from the mesh flows within the neutral-earth network impedances (e.g. the diverted neutral currents DNC). In terms of a 'clean earth' (from an electronics/RF/EMC perspective) it's normally the separation of the protective earths that connect to 'noisy' equipment, from those that connect to the sensitive equipment, such that they come together nearer the power return point, and avoid cross bonding that would run some of the high power earth return 'noise' through the clean earth wiring. It all sound very reasonable until one starts considering the local capacitance between the separated earths, which at the RF frequencies then provide a significant conduction path through their Xc @rf. Cue, lots of arguments and opinions... ~1:47:00 Paul's comment regarding Lightening bonding on the roof injecting the lightening into the building is /surely/ an extreme example of the clean earth problem ;-) Great talk and questions.

@e5Group

8 ай бұрын

Glad you liked it, great points. I was knackered doing this.

Next talk ungrounded or unearthed systems the where and why- think operating rooms…..

Why can't we combine voltage operated elcb with rcd in that voelcb takes care of ground earth fault and rcb takes care of small leakages.