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#53100 06/17/05 07:07 AM
Joined: Mar 2005
Posts: 1,803
Member
Quote
Live entertainment is not good with dead performers. This is a bad idea.

Depends who it is. [Linked Image]

Alan.


[This message has been edited by Alan Belson (edited 06-17-2005).]


Wood work but can't!
#53101 06/17/05 07:18 AM
Joined: Jan 2003
Posts: 4,391
I
Moderator
Good one Alan. [Linked Image]

Working at concert venues, I only see the lower end sound guys with 'ground lifts'

It is always the people with a little knowledge that think they have found a better way.

There should be no reason for a ground lifts if the audio company has professional power distribution equipment. That takes the buildings system out of the picture.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
#53102 06/17/05 09:42 AM
Joined: Dec 2003
Posts: 886
H
Member
A listed occupancy sensor with the equipment ground removed--Test Points are device yoke, and grounded switchbox.

What is the supply voltage, the meter shows 265? I question the validity also because this is a high impedance meter, you are probably measuring leakage. Put a resistance across the test points and it will go away.

-Hal

#53103 06/17/05 01:41 PM
Joined: Nov 2004
Posts: 32
S
Member
Also remember where the equipment is manufactured is often in Japan, and perhaps the instructions are simply translated to English from Japanese instead of rewritten.

Funny about the non-pertinent instructions, I bought a new Sony Videocamera a few months back and found in the box a Safeguard guide that was full of non-pertinent safeguard warnings and was dated 1988.

#53104 06/17/05 07:30 PM
Joined: Dec 2000
Posts: 4,294
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The supply voltage at this time was 265 Volts from a nominal 277V system.
This particular model sensor has an equipment ground which the directions say must be connected for proper operation.
I believe the same model used to come with a neutral connection.

A resistance? How about a finger? The reason I took this picture was because someone told me that they had found one of these hanging out of a wall in an office aand had been shocked. I don't know why it was out, but this is the result. Believe it. Maybe I'll smash one and look inside, I'll post results.


[This message has been edited by electure (edited 06-17-2005).]

#53105 06/17/05 08:44 PM
Joined: Jan 2005
Posts: 5,445
Likes: 2
Cat Servant
Member
I suppose that I ought to expand a little on the "stuff that uses the ground path as a 'neutral' for the electronics."
I first saw this with some cheap timers. I later saw ti with soemphotocells.
There are a few clues that warn you this is the case. The most obvious is the lack of a neutral wire, along with a strong caution that the device will work properly only if installed wit a well-grounded circuit.
Another clue is a caution that the device may not work properly if there are other sensors or switches on the circuit.
Usually these are the cheaper controls.

The current flow in these cases is in the milli- or micro- amp range. In fairness, I have no idea as to just how much current is allowed. Also, there might be other electronic issues here besides operating current- I personally lack the patience to sit at a tech bench!

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