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u must have/use 4 wire.
Don't you mean from either hot to neutral?...The 120V loads go from either hot to ground...
Yes, that was what I was planning....The duplex was split so the top half was on one hot and the bottom was on the other. That way I could run two high-current 120V tools from the same outlet.
Yeah, I can't believe I wrote that. Edited.Don't you mean from either hot to neutral?
Hmmm. Didn't he say that the original existing dryer receptacle was 4 prong ergo fed with 4 conductor cable?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. .
In the opening post:You cannot use the existing 3 wire dryer circuit to add a sub panel as it requires 4 wires.
In the garage at the moment is one 220V outlet, four prong, for a dryer.
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
Need a joed or JV or brric or somebody to comment:Here's the electrical question....
1) Is it acceptable to provide the 110V to the outlets by using one of the two hot legs of the 220V, or do I need to pull a three conductor wire for the 110V in addition to the wire for the 220V outlet?
2) Since the RAS has only a three-pin plug, Hot-A, Hot-B and Ground, is there any reason to even pull 4-conductor wire for the 220V if I pull separate wire for the 110V? Obviously if I can use one of the hot legs of the 220V for my 110V then I have to pull four conductor because I need the common neutral, but if I can'y can I just use three conductor wire for both?
Thanks for your help,
Richard
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 MWBC
Since I seemed to be getting conflicting answers, I googled some more, and found a site that discusses the NEC itself. (Thank you AllenJ for providing the proper name for this circuit so I knew 'what' to Google!)a7ecorsair said:Electrically it would work but I can't believe it would be compliant.
I would like to see the reference where you found this.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 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.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.
The NEC is generally restrictive, not permissive. If something is not prohibited by the code, it is allowed. Note that HouseHelper did find a provision that specifically addresses this, though.I would like to see the reference where you found this.
I am a "working electrician" and this is definitely allowed... this is no different than a dryer or range circuit, which is a 120/240V MWBC!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.
here it is straight from the nec
210.4(C)
Line-to-Neutral Loads. Multiwire branch circuits
shall supply only line-to-neutral loads.
Exception No. 1: A multiwire branch circuit that supplies
only one utilization equipment.
Exception No. 2: Where all ungrounded conductors of the
multiwire branch circuit are opened simultaneously by the
branch-circuit overcurrent device.
Agreed, I've only been a licensed electrician for about 10 years. All i have to go by is past experience, and i can honestly say that I haven't done this, nor would i do it and I can think of LOTS of times I had the opportunity to do this wiring method. If it was me and in my opinion i would just run a 12/2 for the 120v stuff and leave the 240v stuff on a dedicated circuit. This is an interesting topic though, I have a meeting with a state inspector tomorrow in Boston for a job, I'm gonna run this by him and see what his opinion is. Maybe he can reveal a secret code article.This section to me has been a topic of confusion more than once, but im leaning in the direction that you MAY do this as long as they are the same amperage, and have a simultaneous disconnecting device, thinking logically, if EITHER of the two legs exceed amperage, it will trip both legs, and on the other end if you need to shut of either of the circuits for service, you will be forced to shut off both to eliminate the hazards of neutrals....