Re: Scope grounding and generators


Bob, I am reproducing your email with a few response comments...  and it
might also be helpful if you indicate what type of generator you have
(KW rating, voltage/phases output, etc).  Also, whether you plan to
monitor the generator's output with the scope receiving AC power from
the house, or the generator itself:

On 10/24/20 9:59 PM, Robert Simpson via wrote:
Also, I just checked the main breaker panel and the ground and neutral are on the same bus bar.
US National Electrical Code requirements call for the neutral (grounded
conductor) to be bonded to the ground (grounding conductor) at the
"service entrance" of any building service (but nowhere else); this is
in accordance with "code".
My extension cord for the scope will have a triple tap on the end. So I can use one of the ground hole sockets to connect to the generator frame lug for this test . That way the scope ground and generator ground will be connected electrically close.
Yes, this will serve as an interconnection between the house ground
system and any other loads (such as a scope plugged into the extension
cord), or the generator's ground system.  However: make sure that the
wiring from the house to the scope (or generator) has not been
compromised (insofar as maintaining the correct continuity of
identification/wiring of neutral, ground, and "hot" wire) all the way
from the service entrance, through intermediate outlets and the
extension cord, to destination load(s) or generator.

And you probably already know this, but I'll state it anyway- don't
under any circumstances interconnect the neutral and/or "hot" wires
between the house and the generator.

Mike D. N4MWP


Join to automatically receive all group messages.