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Author Topic: Dangerous Practices Stefan Scholz Expert Film Handler Posts: 223 From: Schoenberg, Germany Registered: Sep 1999 posted 09-22-2001 02:25 PM                        All my booth installations have 0.03 Amp GFI priojection in the mains supply. Even with all the RFI filters in modern sound gear and electronic lamp supplies they never tripped. So in case, you touch a live wire, and the current would exceed the 30 mA, which is not considered lethal, the switch will trip. It is also a good fire insurance, as cable fires will at some point cause an unbalanced leakage of greater than 30 mA, at that point creating not enough heat to start combustion. I know, people mainly tend to use GFIs only in wet rooms or bathrooms, but it is a $100 life insurance (for a good 60 Amp 4 pole type) worth it. And if it tends to trip regularily it indicates a fault needing cure.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 09-22-2001 04:52 PM                     Some GFI's have problems with switch mode devices connected to them and dimmers that use SCR/triac chopper circuit  |  IP: Logged Josh Jones Redhat Posts: 1207 From: Plano, TX Registered: Apr 2000 posted 09-23-2001 01:11 PM                        If you put some sort of RF suppression on the line, I cant see why there would be an issue. Those dimmers create so much RF anyway, its a wonder the FCC hasnt banned some of the worse ones by now. Most modern dimmers have large chokes in them to remove most of this radiation, but the output of the dimmers still looks like a ramp, which can cause RFI if the waveform is not changed into something that looks like a sine wave. Josh  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 09-23-2001 02:28 PM                     Most of the sound system related problems are not RF related but actual spikes. Most dimmers are far better filtered than you think. The choke used in most professional dimmers limits the rise time to better than 350 usec.  |  IP: Logged Bernard Tonks Jedi Master Film Handler Posts: 619 From: Cranleigh, Surrey, England Registered: Apr 2001 posted 09-24-2001 10:31 AM                     A very nasty experience you had Pete, hope you have fully recovered and able to continue your work normal and not nervously. Three years ago a projectionist was electrocuted at the Rivoli ABC Southend, something to do with a light fitting I believe. The only cinema fatality I know of, one too many! Just seen on the UK projectionists’ website that in your part of the land, sadly the listed ABC Muirend closes 21st October. http://groups.yahoo.com/group/cinemationlist  |  IP: Logged Pete Naples Phenomenal Film Handler Posts: 1565 From: Dunfermline, Scotland Registered: Feb 2001 posted 09-24-2001 10:58 AM                     I'm fine Bernard, thank you for your concern. Most of the gear I work on was installed by me or my colleagues, so I can literally trust it with my life. It's the actions of others that you can't trust. Most of the ABC's have gone, all the ones I ever worked in are closed, that last one I was in, Lothian ROad, Edinburgh, was demolished, but is set to rise again with a four screen multi on the site. Those were good days, and good old barns of theatres, but their day is gone, sadly.  |  IP: Logged Andy Muirhead Master Film Handler Posts: 323 From: Galashiels, Scotland Registered: Dec 2000 posted 09-24-2001 08:21 PM                     Pete, thanks for your mail, as suggested my suspicion was indeed correct. I advise any other Monee users to check the terminal strips located in the exciter lamp-house. There is no way this should be used for mains voltage. As Pete says, this has been used for powering the lace-up lamp within the projector. If you find there is mains routed through these connectors, you have two options- Cover the strip connectors with electrical insulating tape or- Just disconnect it - Its what i have done, those lamps are useless anyway.  |  IP: Logged

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