Which wire is hot?

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  #1  
Old 02-14-02, 02:00 PM
rreinhar
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Which wire is hot?

I'm rewiring a box to switch to light fixture.
The wires connected to the switch are both white, while the black wires are just connected together. Does this automatically mean that the white wires here are hot?

On the cable that brings power into the switch, how would you tell which wire is hot?
Thanks
 
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Old 02-14-02, 02:08 PM
G
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You will need some sort of tester. You can test between the wire and the ground you should have 0Volts on the whites and 120V on the black. The white wires are never to be used for switching. If it turns out the black is hot then put the switch to it and wirenut the whites together. If it turns out the whites are hot you should rewire both the outlet and wherever it is fed from. You should end up with only colored wires as hots and whites and greys as neutrals.
 
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Old 02-14-02, 05:55 PM
rreinhar
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Fair enough. One question though.
You say one should never have the whites connected to the switch. Is there a functional reason for this, or is this just standard practice that will eliminate confusion in the future?
 
  #4  
Old 02-15-02, 05:23 AM
G
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It is in both the codes for Canada and for the U.S.
It is for safety of personel and fire safety.
If a neutral is switched and the switch is off thenit is assumed
it is safe to work around it is not the hot wire still
is dangerous and if you short it to ground your liable
to kill yourself or someone close to you.
Code 4-028 in the CEC tells us the neutral or identified conductor which is normally grounded is itdentified by a white coating.
Therefor the black can't be the neutral.
Farther along in the code it is stated the white wire cannot be
part of the switch leg.

But the most important point about it is the danger it can present to
anyone working around it. Repair it and be done with it
 
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Old 02-17-02, 05:26 AM
M
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your right about the neutral not being used to carry curent however it often does when wiring with Romex. Example ceiling box with hot and neutral, 14-2 romex run to the light switch...neutral is used as the hot and the black becomes the switchleg.
 
  #6  
Old 02-17-02, 10:39 AM
G
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The white or grey conductors is considered the grounded conductor not to be confused with the bare wire which is the grounding conductor which means it is to be the neutral of a system. At no point should it be a hot wire without being remarked.

250.26 Conductor to Be Grounded Alternating-Current Systems.
For ac premises wiring systems, the conductor to be grounded shall be as specified in the following:
(1) Single-phase, 2-wire one conductor
(2) Single-phase, 3-wire the neutral conductor

250.186 Impedance Grounded Neutral Systems.
(B) Identified and Insulated. The neutral conductor of an impedance grounded neutral system shall be identified, as well as fully insulated with the same insulation as the phase conductors.
(C) System Neutral Connection. The system neutral shall not be connected to ground, except through the neutral grounding impedance.

200.7 Use of Insulation of a White or Gray Color or with Three Continuous White Stripes.
(A) General. The following shall be used only for the grounded circuit conductor, unless otherwise permitted in 200.7(B) and (C):
(1) A conductor with continuous white or gray covering
(2) A conductor with three continuous white stripes on other than green insulation
(3) A marking of white or gray color at the termination
(C) Circuits of 50 Volts or More. The use of insulation that is white or gray or that has three continuous white stripes for other than a grounded conductor for circuits of 50 volts or more shall be permitted only as in (1) through (3).
(1) If part of a cable assembly and where the insulation is permanently reidentified to indicate its use as an ungrounded conductor, by painting or other effective means at its termination, and at each location where the conductor is visible and accessible.
(2) Where a cable assembly contains an insulated conductor for single-pole, 3-way or 4-way switch loops and the conductor with white or gray insulation or a marking of three continuous white stripes is used for the supply to the switch but not as a return conductor from the switch to the switched outlet. In these applications, the conductor with white or gray insulation or with three continuous white stripes shall be permanently reidentified to indicate its use by painting or other effective means at its terminations and at each location where the conductor is visible and accessible.
So if the white is hot you should change the system to comformed with the Code.
 
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