Can someone tell me if the Canadian electrical code requires an ground
wire to be connected to a light switch, I always connected the ground to
the box, but a fellow electrician just told me they now need to be
screwed onto the switch.
Maybe they changed it to make it more "one size fits all"
Consider metal boxes vs plastic boxes.
Since the switch screws into the metal box with metal screws,
grounding either grounds both. Obviously with a plastic box, the only
way to ground the switch is to attach the wire to the switch.
If they write the code to say that the wire must be attached to the
switch, both situations would be covered without any ambiguity.
Canadian plastic boxes have a metal grounding strap installed to attach the
grounding wire. I have personally not seen on/off switches with ground
screws, but timers, X-10, scene controls and dimmers often need a ground
wire. I think that ground wires "must" be attached to the box first, then
connected with any other ground feedthrough wires and a pigtail (if the
switch doesn't have its own pigtail) to connect to the device exactly like
grounding a receptacle.
The light switches that I've dealt with do not have a ground
connection...only the receptacles.
Receptacles, on the other hand, normally have the ground conductor
connected to the receptacle as well as the box (if the box is metal).
Most pictures of US plastic boxes do NOT have a ground strap, so possibly
they require switches to have a ground screw to anchor the ground wire and
to ground the switch frame.
Canadian plastic boxes have a ground strap that provides a ground screw the
same as a metal box. The strap then runs up to where the devise is attached
by its screw, grounding the device frame on a switch. This is probably why
Canadian switches do not need a ground screw on the switch frame.
I must be missing something here, because neither have I ever seen a light
switch with a ground terminal on it, nor can I see the utility in having
a ground terminal on a light switch. But here's a link to instructions on
how to wire a light switch, and said instructions don't show any ground
terminals in play.
Now, as to whether the metal frame part of the switch should be grounded
by contact with a grounded box, that's different. But I don't consider
the part of the frame that mounts into a box to be a terminal.
What am I missing here?
You're kidding right? If not, why not try googling "light switch" and do
a couple days worth of reading. The switch is grounded for the same reason
anything else is grounded. so if it shorts to the frame, YOU DON'T FRY.
Again, do you have a link to a picture of a modern light switch that does
NOT have a ground screw on it?
You can't buy them new because a ground is required by code now.
However, about 15 years ago I bought a bunch of outlets and switches for a
shed with extras for the garage we were going to build. When we finally got
around to building the garage, I installed them, not realizing the codes
(and the new switches) had changed. The inspector noticed immediately
(based on my experience, grounds are the FIRST thing the inspectors look
I don't know when the change took place, but it must have been close to the
time we built our garage (2001). The inspector approved the installation
anyway, saying we "probably just got an old box of switches". I doubt any
inspector would allow them today.
For the most part, an ungrounded switch is safe, because the cover plate is
plastic and the switch handle is plastic. However, if there was a short in
the switch, the screws that hold on the cover plate could be energized.
It's an unlikely situation, but it could be very dangerous.
Switches have ground connections. Use them.
I purchased the switches and outlets long before then, I'm guessing around
1990 or so. The outlets were grounded, the switches were not.
In any case, you won't find the ungrounded switches for sale today, but I
was just verifying that at some point ungrounded switches were commonly
What would be the advantage to grounding a switch? I see none.
Ask your electrical inspector or an electrician about the code. A good
one will be more than willing to help. Replacing a switch does not
entail a permit.
No reason to ground something doesn't stop them from wanting it grounded.
OK, to prevent the metal part of the switch from going hot in the event of
a fault. But why does my plastic bodied Dremel have a polarized plug?
That's a guy who never had a Dremel apart. They have a plastic sleeve
between the chuck and motor that is the load limiting device. They do
strip out or twist in two if you overload the Dremel. Since the chuck
bearings are set in the plastic case it is isolated.
The polarized plug is just there to be sure you are switching the
"hot" leg per U/L listing standards.
As for grounding switches, it is because of metal covers or metal
screws to that cover. Back in the olden days you got plastic screws
with a plastic switch cover. They frequently got replaced with metal.
I suspect you are going to see that metal bonding strap in US boxes
soon, at least in Florida. We just changed the building code to
require bonding metal studs, that are very popular here. That can be
done with a metal box via the grounding conductor or via a plastic box
with metal bonding straps that also catch a metal mounting flange.
This seems to depend on the age of the Dremel. I have one that's
probably 20 years old (sold as Sears Craftsman, but identical to the
Dremel-labelled ones of the time) which is as you describe. The motor
armature is carried by two bearings, while the output shaft has its own
two bearings, and the shafts are coupled by a plastic splined piece.
The trouble with this construction is that the output shaft has lousy
stiffness against any side loads because it's carried by two bearings
only a half inch apart, and both bearings are clamped (somewhat loosely)
in a plastic housing. It means this particular Dremel chatters like mad
if you try to use it as a router or with a side-cutting milling cutter.
It's only usable for drilling, buffing, etc.
I have more recent Dremels where the output shaft goes all the way
through the motor, there are only two bearings supporting it, and they
are 3 or 4 inches apart. This design is much stiffer against side
loads. I don't know exactly how Dremel continues to make it
double-insulated without the double shaft design; perhaps there's an
insulating sleeve between the shaft and the armature iron. But Dremel
has changed the mechanical design to eliminate the stub output shaft.
I think grounding of switches appeared in the US-NEC to provide a ground
for metal plates. Switches have to be grounded by:
1 - attachment with metal screws to a metal box (or plastic box with
integral grounding means).
2 - ground wire attachment to a grounding screw on the switch (used for
(there are exceptions)
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