AW: To earth, or not to earth...

media at media at
Fri Dec 5 09:42:07 CET 1997

>> By the way, metal chassis should be connected to earth, i.e. power
>> supply earth, water pipe, whatever. To avoid electric shock hazard.
>Is there any regulation (VDE or so) that says circuit ground has to be
>connected to Protective Earth? This connection is made in many devices
>and it causes trouble again and again. If there is such a regulation,
>what about laboratory power supplies? They always have earthfree outputs.
>If there is not, why do so many manufacturers implement this connection?

I have no idea about other countries, but yes, there are laws in the U.S.

I am not a lawyer or an EE, but there are different laws for different
types of equipment, and certain laws that only apply to public gatherings
and performances, and different laws for places of work.

I've heard some of these laws can be very silly, as the law isn't written
by engineers.  It is better to check with your local codes than get shut
down by the fire marshall.

For example, in doing live sound, all equipment that uses power from the
mains must be grounded (or bear the double-insulated symbol -- quite rare
for audio equipment, no idea what the law is on wall warts), no resistance
between chassis and ground pin greater than 0.5 ohm, no exposed voltages
over 25V, all insulation rated at 500V, regulations on speaker cable
voltages, etc.


"I know that I can come off as a little proactive, and for that I'm sorry."
                                                  --  Homer Simpson

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