[rjniles]

Is this garage a detached structure from the house? Or is it attached? The answer to that question makes all the difference in the world.

Assuming it is attached: You can not use a single circuit to provide both 120 & 240 volt receptacles without a sub panel. You cannot use the existing 3 wire dryer circuit to add a sub panel as it requires 4 wires. What you could do is use the existing dryer circuit to provide a 240 volt circuit for your saw. Change the breaker to a 15 or 20 amp double pole. Run a new 12-2 cable from the breaker panel to install the 120 volt receptacles.

If the garage is detached, ignore what I have said above.

 

[rjniles]

My answers in red

Hmmm. Didn't he say that the original existing dryer receptacle was 4 prong ergo fed with 4 conductor cable?

Missed that Allan.With a 4 wire he can add a sub- panel to replace the existing dryer receptacle.

The saw, meanwhile, was 240 volt only with 3 prong plug (one ground prong).

Hmmm. You mean you can't run a traditional MWBC* (a 120/240 volt circuit) to a box with a 240 volt receptacle and a (or a pair of) 120 volt receptacle in it?

A MWBC is used to get 2 120 volt circuits, not for both a 120 and a 240. If it is used for a 120/240 volt circuit it is not a MWNC

 

[rjniles]

A MWBC can indeed provide both 240 and 120, so long as the fault protection is correct. On a MWBC providing only 'out of phase' 120V service, that can be 'either' a double pole breaker or two single pole breakers with a handle tie. The NEC requires that a double pole breaker be used if the MWBC also provides 240V service.



Richard

I would like to see the reference where you found this.

 

[rjniles]

Section 210.4 (C) Exception 2. Basically says you may use a MWBC for line to line loads IF you protect the circuit with a common trip double pole breaker.

I have reread that exception and exception #1 about 3 or 4 times and do not believe the intent is to allow the use of multiple line to neutral and line to line loads on the same MWBC. Maybe we need input from one or more of the working electricians on this forum.