Electricity went out in 1
In workshop areas, the NEC specifies GFCI (ground fault circuit interruptor) outlets.
If you replaced any GFCI outlets, there could be 2 possible problems:
(1) modern GFCI outlets will pass zero voltage if wired backwards (i.e. a load/feed reversal).
check the load/feed wiring of all GFCI outlets, to make sure its correct.
The feed side of the GFCI outlet is wired directly to the breaker, and the load side feeds power
to the remainder (the downstream side) of the circuit (therefore protecting the entire downstream
side of the circuit).
(2) older GFCI outlets could need to be reset if wired correctly - check the reset button(s) just to
make sure that they (and any downstream outlets) are receiving voltage.
Assuming that no GFCI outlets were part of the replacement process (or that your GFCI outlets
are correctly wired), your check for the presence of 240 VAC
should begin at the outlet/switch closest to the 240VAC double pole breaker, and proceed from there (looking for that 240VAC at each device with your 2-prong tester) along to the end
of the circuit until the problem is identified.
What this implies is that you have created (or will create) a schematic or circuit diagram of the
circuit involved - including switches, wires, and outlets (240V and 120V) - and then use that as a
resource to trace the possible sources of the problem from the breaker to the problem.
Here's the question I would want you to answer as you create your circuit diagram:
How did a 240V table saw get on the same circuit as a 120V washer and/or 120V switch(es)?
It seems like during the process of circuit tracing/diagram creation, you may find
that you're dealing with parts of more than 1 circuit, rather than just one. Check the breaker box
for any breakers that are in the "Tripped" position - and diagram those circuit(s) too.
What I would suspect is a wiring problem/mistake with the 1st device (switch or outlet) that is
supposed to feed power to the rest of the circuit, but fails to pass power on to the remainder of the circuit - or that that first device is actually wired to a second circuit with a tripped breaker.
Another thing to check is that your shop may be on its own sub-panel, with the table saw
on a 240VAC circuit, and the washer on its own 120VAC circuit. In this case, the
total curent draw may have tripped the MAIN breaker to this sub-panel in the MAIN breaker
panel (i.e. none of the breakers in the sub-panel were tripped, but the main breaker feeding the
ENTIRE sub-panel tripped, and this (double pole) breaker is located in the MAIN breaker panel).
In this case, the fix would be to reset the double pole breaker in the main panel that feeds the
shop sub-panel, bringing all the sub-panel circuits on line.
The last thing to suspect/check for is a fault in the wire itself, which is the most difficult problem to
diagnose. The fix to a bad wire would be re-fishing a new wire from the breaker box to the 1st
device box - no electrical inspector will require the removal of old wires from walls - so long as they
are not live.
What would make your life alot easier, and what helps electricians diagnose these problems so
quickly, is an electrical field tester (a.k.a. "chirper" tester), which would allow you to check
the wire as it leaves the breaker box to the point where the electrical field disappears.
At the point (point in the wire/outlet/switch) where the chirper stops chirping, you've found your
fault. At Home Depot/Lowe's/electrical supply store, a electrical field tester will set you back
about $8 to $20, depending on whether you opt for one that just lights an LED, or one that
lights and LED and also chirps.
