In article ,
Steve McDonald wrote:


Thank you for all of the advice, although some of it appears conflicting.
I have examined and traced the wiring from the in-slab 240V metal table saw
outlet back to the panel. Here is what I see:

There are 3 wires going into the saw outlet from the panel end: BLK, WHT and
GRN.
The BLK and WHT are connected to the two hot prongs while the GRN is
connected to the center pin as well as to the metal box.
These wires then go into the concrete slab through a pipe. I can't tell if
it is metal or plastic.
The wires re-emerge about 10' away in a junction box in the wall, From here
they connect with another cable that returns to the breaker panel.
This cable has a RED, BLK, WHT and BARE wire. It is connected to the saw
wire as such:
BLK-BLK, RED-WHT, BARE-GREEN. The WHT wire (from the breaker panel) is
capped off.

What are the new implications of the WHT wire not being employed?

Simply that it is a 240V *ONLY* sub-run. That _connected_ WHT wire (going
towards the saw outlet) _should_ be tagged with some black tape, at *both*
ends, to indicate that it _is_ a 'hot' lead, and not a 'neutral'.


Is it safe
in this configuration?

Assuming everything else is done correctly, _yes_.


Sounds like it should be re-wired with a 4 wire system as so many have
suggested.

It's perfectly OK, as is, for a _240V_only_ device.

However, if you _really_ want that 120V outlet as well, then yes, you
_must_ modify the wiring from the saw outlet to the point where it
ties to that other cable. Note: you'll also have to investigate the wiring
between the outlet on the wall, and the saw itself. You may have to replace
_that_ wire, as well, to get a real 'neutral' all the way to the saw.

Getting a 'neutral' to the saw outlet will involve pulling another wire
through that pipe -- I'd recommend RED, using it for the 2nd hot, and
're-converting' the WHITE back to the 'neutral'. Be sure to remove the
black 'tagging' from both ends of the white lead.

There are some ways to do the 120V outlet, without pulling the additional
wire, *BUT*, they are contrary to building-code virtually *EVERYWHERE*,
and, regardless, are _extremely_ dangerous -- there are 'failure modes'
that can *kill* you, even if you don't touch anything connected to the
120V outlet.