Black or Taped, Which Wire Sends Power TO The Switch?

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  #1  
Old 09-26-01, 01:06 PM
MKM
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Hi,

(My gut feel is Scenario 1, but I'd rather ask the experts...)


In the diagram below, power comes in from the left,
enters a box which holds a light fixture,
and continues on to a box that holds a switch

================LIGHT==============SWITCH
incoming


Which of the following is (more) correct ?


Scenario 1

In the LIGHT BOX, Connect the incoming (left) black wire to the outgoing black wire.
In the SWITCH Box, connect the black wire and white wires to the switch, and tape the white wire black.
In the LIGHT box, tape the returning (right) white wire black, and connect it to the light fixture's black lead
In the LIGHT Box, connect the incoming (left) white wire to the light fixture's white lead.


Scenario 2

In the LIGHT BOX, Connect the incoming (left) black wire to the outgoing (right) white wire - Tape the outgoing white wire black.
In the SWITCH Box, connect the white wire and black wires to the switch, and tape the white wire black.
In the LIGHT box, connect the returning black wire to the light fixture's black lead.
In the LIGHT Box, connect the incoming (left) white wire to the light fixture's white lead.


Thanks...

...Mike

 
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  #2  
Old 09-26-01, 01:11 PM
resqcapt19
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Mike,
Scenario 2 is required by 200-7(c)(2). Scenario 1 would be a code violation.
Don(resqcapt19)
 
  #3  
Old 09-26-01, 01:41 PM
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yes...#2, and feed the top of the switch with the 'tapped' white.
 
  #4  
Old 09-29-01, 10:49 AM
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Top of switch. WHY

Originally posted by wirenuts
yes...#2, and feed the top of the switch with the 'tapped' white.
Why would there be a preference for which terminal to use on a fully enclosed snap switch. Be advised I am using snap switch as it is used in the NEC to mean a common single pole, strap mounted switch with no exposed current carrying parts except the screw binding terminals. The reason that scenario two is correct is that in the absence of the marking tape, due to later removal by someone unfamiliar with the circuit, the connection of a black wire to a white is a tip off to qualified persons that a cable is being used as a switch leg. As long as the splice is not disturbed the two wires left for connection to the luminaire are the correct polarity.
--
Tom
 
  #5  
Old 09-29-01, 02:14 PM
Wgoodrich
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The NEC requires that the white feed power to the switch. This is because of the power requirement to smart switches and other new products on the market that can be damaged by reversed polarity.

To my knowledge there is no requirement on a single pole switch to connect the white to the top. I suspet that wirenuts is speaking a preferance there instead of an NEC requirment.

Wg
 
  #6  
Old 10-01-01, 09:03 AM
Gary Tait
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I thought it was so one could not be confused as to which is
hot and neutral in the fixture box.
 
  #7  
Old 10-01-01, 01:26 PM
Wgoodrich
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Gary you are right as to the reason that you can not connect a white going to the light fixture as an ungrounded conductor thus bringing the prohibited hot white to a light fixture that use of a white wire is prohibited altogether [powering the fixture with a white wire]. The part I was talking about was the white that the NEC allows to be used as an ungrounded conductor requiring it to be re-identified within that switch box as an ungrounded conductor but also requiring that conductor to be connected to power the switch instead of power from a switch such as in three and four way switches. I guess they both run together but in discussions at conventions both subjects of prevention was discussed.

Wg
 
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