Its a question more than a statement, for the time being at least, and strictly speaking I should call it "Incidents of Overheating". Anyway, I am currently investigating the circumstances surrounding two incidents at the same flat, within a council block of flats where the electrical lead has been subject to an overload. On both occasions the overload has passed only through the earth wire, within the lead. Faults within the domestic earth supply, the TVs and surge protection devices are all confidently eliminated, as are other non-electrical causes, such as arson, rodent infestation and external heat source. On no occasion have any of the protection devices in the appliance, plugs, leads or domestic circuit operated.
I have relied on assistance from external experts but the conclusion we are headed towards is an earth fault on a digital aerial that is split and boosted (at mains voltage) to more than 12 flats. There are a lot of interested parties in this case that has actually caused no real damage (thanks to an alert occupier and smoke detectors) but the potential for serious consequences is significant and depending on the agreed outcome (if that's possible!) could be far-reaching. I have sent a FINDS message out referring to this incident within the UK FRS community but if anybody else in the world of fire investigation has come across similar scenarios it would be interesting to hear of them.
Best regards, Alan
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I have come across a similar situation in domestic properties where DIY aerial extensions and splitting has resulted in overheating of components within splitters causing browning to the plastic of the splitter. This did not result in fire either but was brought to my attention by a switched on operational WM. (I have also seen similar with overheated components within devices such as rodent scarers; the type that emit a hypersonic sound wave). On both occasions it looked to me on inspection to be overheating of resistors within the circuitry. Most of these components are now made in the far east and have to be used in various countries with varying voltages. In the case of the splitter; it was an RF coaxial cable one to two splitter being used with coaxial cabling to carry a cable TV signal, the current for cable TV being most probably significantly higher than the induced signal from a TV aerial notwithstanding any post aerial signal boost. It would be interesting to ascertain the exact current used to carry cable supply digital signals as opposed to induced RF or Digital EM? Anyone know?
ReplyDeleteAlan. I have a case pending now where a steet mains power fault has resulted in power being transmitted into the comunal aerial system in a modern block of flate via the signal booster. It caused one fire in a tv, one burned tv aerial co-axial cable joint and (allegedly) two plugs thrown from sockets. Call me some time for detail if you need it.
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