Newsgroups: rec.arts.theatre.stagecraft
Subject: Re: LDI (Re: Tran-Siberian Orchestra Pyro)
References: <829d3faa-3379-4cc6-b3dd-fd712eda1599@b36g2000hsa.googlegroups.com>   <3030839c-cf8b-4da8-bfe9-83b935f8ddc8@s19g2000prg.googlegroups.com>   
Christian Marg  writes:

> Omni.Tech wrote:
> > On Nov 20, 9:42 am, Christian Marg 
> > wrote:
> [...]
> 
> >> Use a bipolar meter (rated for that usage) to detect voltage...
> > 
> > Not a Unipolar?
> 
> Hmm - not sure about the Term: I am thinking about one you connect to
> two different conductors to check if there is a voltage between them:
> 
> Look at http://images.google.com/images?q=duspol for an Image of what I
> mean...
> 
> In Germany we have "Phasenpruefer" (don't know an english word for it
> yet): A Screwdriver with a neon bulb in it. You put your Thumb on its
> end and its blade to a conductor: If the Bulb glows, there is some
> Voltage on the conductor.
> 
> But: Our electric code demands a "bipolar" voltage check, because the
> "Phasenpruefer" also glows if you put the blade to a wire with an open
> end running parallel to one with voltage...

There is always other case where "Phasenpruefer" can fail. 
The "Phasenpruefer" can fail in case you are very well insulated 
away from ground sources. In that case there is not enough 
"leakage" through you that the would make the neon bulb to flow. 

So the electrical code in Finland as well demands using a 
"bipolar" voltage check to make sure that there are no 
electricity on the wire before starting working with it.

There are different types of voltage tester that work quite similarly 
to screwdriver with nenon bulb on it: 
http://www.maplin.co.uk/Module.aspx?ModuleNo=10294&doy=22m11&C=SO&U=strat15
http://www.maplin.co.uk/Module.aspx?ModuleNo=30584&doy=22m11&C=SO&U=strat15 
http://www.maplin.co.uk/Module.aspx?ModuleNo=45560&doy=22m11&C=SO&U=strat15
http://www.maplin.co.uk/Module.aspx?ModuleNo=12840&doy=22m11&C=SO&U=strat15


-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/