[Boatanchors] AC Meter Shunt Help]

[rbethman at comcast.net]

Ed,

Personally, I would NOT use a CT!  They can DEFINITELY be dangerous!

Thirty-two years ago I had the UNFORTUNATE albeit VERY LUCKY chance 
occurrence to be the victim of a CTs issues.

I ended up thrown over thirty, (30), feet because of one.  The blessing 
was it was a hot AND humid day in American Samoa.  I was working on a 
13,800 VAC switchgear skid.  I was about to tie-in a tie-line between 
two such skids.  Both circuit breakers, (1200 Amp @ 15KV), were racked 
out of the circuit.  The cables were prepared with stress cones and grounds.

A ground strap was placed across the terminals.  The kicker was that the 
strap HAD to be removed to attach the cables, (500 MCM).

The instrumentation that the CTs fed, included over-current relays.

Upon reaching up to connect the FIRST cable, I got my bell rung AND 
tossed the over thirty, (30), feet.  The instrumentation system caused 
JUST what folks refer to as the 'burden' causing a high voltage, albeit 
LOW current to be imposed upon the terminal.

Take a look at VTVMs and DVMs.  They ALL use a hard wire SHUNT to 
achieve their high amp readings.  That's how go from the normal range 
steps, I.E., 200uA, 2000uA, 20mA, and 200mA reading scales to the 10A 
position.

When placed into the 10A position, a solid but tinned copper shunt is 
added to the circuit is placed in the circuit and the meter movements 
ACTUAL full scale is read by the aqcross resistance of the shunt!

A truly MUCH safer method!

Bob - N0DGN