Edward Greeley etgreeley at WORLDNET.ATT.NET
Thu Feb 19 03:57:41 EST 1998

Hello Bill,

Hmmm...   Don't remember (if I ever knew) what the Heath GR-91 was/is
like, i.e., does it have a metal case/cabinet?  If so, it would have had
to have a floating ground arrangement as previously discussed, OR have
all metal parts exposed to the user (cabinet, knobs, etc) TOTALLY
isolated from the chassis if the chassis was directly connected to one
side of the line.  Otherwise, the item could not/would not have been UL
listed and Heath's liability insurance would not have permitted the item
to be sold!  So, when you say you connected the white neutral wire AND
the green Equipment Ground wire to "ground", what do you mean by
"ground"?  If by ground you mean the chassis, AND the item has a metal
cabinet, that is a no-no since the chassis is supposed to be isolated
from the metal cabinet as discussed above, in which case the white wire
connects to the chassis and the green wire connects to the cabinet ONLY.

If the unit has a floating ground as discussed in my previous post, the
line cord should be connected as outlined in that post.  The cabinet, if
metal, would then undoubtedly be mechanically/electrically connected to
the chassis by mounting screws.

If the unit has a "hot" chassis, but is housed in a non-metallic
cabinet, then there is NO appropriate place to connect the Equipment
Ground conductor.  Per the NEC, in NO case should the neutral and
Equipment Ground conductors be connected together at the equipment end.
The NEC only permits neutral and Equipment Ground to be connected at the
same point where both meet and connect to earth ground, normally in the
"service" (main) breaker (fuse) panel.

As an aside, something a lot of folks don't understand, and which is
sometimes done incorrectly, the same rule applies to "branch panels",
i.e., a breaker panel fed by the main or "service" panel.  Neutral and
Equipment Ground MUST be carried through the branch panel seperately!
That's why the neutral bus bar in many panel boxes (called "convertable"
boxes) is isolated from the box.  If the box is to be used as a branch
panel, the neutral bus bar remains isolated from the box and a neutral
(white) conductor connects the bus to neutral in the main panel.  If the
box is to be used as a main panel, there will be a jumper or screw to be
attached to connect the neutral bus bar to the box.  In either case, the
bus bar to which Equipment Ground conductors (usually bare wire at this
point) are connected is mechanically/electrically connected to the box.
Convertable boxes which are used as branch panels will usually require
purchase of an additional bus bar for use as the Equipment Ground
connection point.  So, if you have a branch panel in the garage or shop
or wherever, and all the white wires and bare wires are connected to one
bus bar - it's wrong!

If I've thoroughly confused anyone - my apologies!  Ask and I'll try to

Ed Greeley
Mobile, AL

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