Ok so I have a Tektronix oscilloscope and a function generator. They have a 3 prong power cord that goes into a grounded socket.

But.. then there's this other ground:

http://www.tek.com/service/safety/afg3000/graphics/diagram-lg.jpg

It has a screw like thing protruding from it. I'm sure I can just attach a piece of wire to it and ground THAT. But do I really have to use that ground as well? Isn't it redundant?

I'm just worried because I saw this message engraved on the back:

TO AVOIID ELECTRIC SHOCK ALWAYS CONNECT THIS INSTRUMENT TO EARTH GROUND.

Does that mean the 3 prong gnd or the gnd from the link?

 

I wouldn't worry about the screw terminal, but I would want to be very certain of the quality of the outlet wiring. If the outlet is wired correctly, the case of the o'scope will be grounded properly.

 

Ok thanks! I'm sure the grounding is fine. I'm working in a lab.

 

If you are working on AC lines or very hi voltage then an isolation transformer is necessary. I put mine thru one for that purpose so i don't worry about blowing circuit breakers.

 

TO AVOIID ELECTRIC SHOCK ALWAYS CONNECT THIS INSTRUMENT TO EARTH GROUND.

Does that mean the 3 prong gnd or the gnd from the link?

It is good that you read the warning. You **always** need a grounded power cord.
The reason is that the earth ground of the power cord is attached to the scope
chasis. The EMI filter caps (Y-caps) are also connected to the earth ground.
Without an earth ground the scope chassis is at a voltage level between earth
ground and line (which is a shock hazard).

As for the screw terminal I would check with Tektronix. One picture is labeled "requires
update" the other is "does NOT require update". It almost looks there was an ECO
to the scope that affects the earth grounding which may affect the safe operation
of the instrument.

Call up Tektronix. If this is safety recall they will probably update your instrument
for free (they would be foolish not to).

(* jcl *)