Re: ground question here...

["Eric Davidson" <edavidson-at-icva.gov> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Sundog,

The 'genius' that wired your outlet has probably done so correctly.  The NEC
requires that a 240 volt load be wired with 2 hot conductors and a groundING
conductor, this can sometimes be the conduit itself, and NO neutral.  The
groundING conductor (bare or green) is NOT meant to carry load current and
there will not be any unbalanced current in a purely 240 volt load.  The
neutral wire (white only) is a groundED conductor and IS meant to carry the
unbalanced portion of the load in a 120/240 volt appliance. (I am
capitalizing the suffixes on ground to point out a subtle, but very
important, difference in the neutral and ground conductors.)  The code does
provide some exceptions, and will allow the neutral conductor to be used for
grounding in cases such as an electric clothes dryer.  To properly wire 120
volt outlets you MUST run a neutral couductor and it must be of the same
ampacity as the hot conductors.  My advice is to get a SquareD 100 amp load
center (less than $20 at your home center) and mount it where the 240 volt
outlet is.  Chances are the 240 volt outlet was for a large appliance and
may be on a 60 amp breaker.  This is a good thing.  No the 100 amp box is
not overkill, if you feel it is, use a 40 amp panel and appropriate
overcurrent protection.  Connect the hot wires (any color EXCEPT white,
green or bare) to the appropriate lugs in the load center.  Connect the
neutral or groundED wire to the neutral bus.  Lastly, connect the bare
groundING wire to a separate ground bus, which will cost about $2.  Do NOT
bond the neutral bus to the load center, but DO bond the ground bus to the
panel.  If the outlet was/is connected to rigid metal conduit (and you sound
as if it is) you can most likely do away with the bare conductor and use it
to pull the neutral wire in. In which case you can do away with the separate
ground bus.  If you use the small duplex breakers you can have a total of 12
separate circuits, enough for even the most avid tinkerer.  Hope this helps.

Eric
edavidson-at-icva.gov


>  Hi all...
>
>  Made a rather disturbing discovery the other day.
>
>     I'm putting in a workbench (maybe this weekend?), and have a 240v drop
> right over where it's to go.  I was going to run that into a panel and
give
> myself a few 15A 120v breakers.  But I found that the "genius" that wired
> the garage ran 2 hots and used the bare copper wire as the ground &
neutral.
> Not good.  I can pull 120v from either hot to the ground/neutral, but will
> that be a "safe" ground for the variac or other stuff?  I truly hate
gettin'
> shocked.
>
> Sundog
>
>
>