1) In examining the wiring configuration in one switch junction box (it is a
double switch...both single pole) I see three bare copper wires twisted
together. Are all of them ground wires? And if so, how do I attach the three
wires to TWO grounding screws??
2) What are the dangers of leaving the bare wires as is, without connecting
any to the grounding screws?
I'm fairly handy, but not a pro when it comes to electrical work. I want to
make sure I'm not doing something risky, as this is something I'd like to do
in other rooms in my house, and can't afford to hire a pro to do it. Thanks
in advance for your help.
Deb
That is correct. Old switches were rarely grounded. Decora's seem
to always be. Mostly this is done because of the prevelence of using
plastic boxes these days. You can't rely on the metal parts of the
switch to be grounded just because they are screwed to the box.
>
> 1) In examining the wiring configuration in one switch junction box (it is a
> double switch...both single pole) I see three bare copper wires twisted
> together. Are all of them ground wires? And if so, how do I attach the three
> wires to TWO grounding screws??
All bare wires are grounds. Twist some more short bare wires into the
bundle (this may or may not also need some sort of fastening device,
seems to vary via municpality).
>
> 2) What are the dangers of leaving the bare wires as is, without connecting
> any to the grounding screws?
The metal parts of the switch aren't grounded. Since the ones in the
box
weren't before, you probably are no worse off than you were before. But
since you have the grounds, you might as well add them.
The "pros" are undoubtedly making some assumptions and their answers vary
based on those assumptions (or perhaps their actual competence).
: 1) In examining the wiring configuration in one switch junction box (it is a
: double switch...both single pole) I see three bare copper wires twisted
: together. Are all of them ground wires? And if so, how do I attach the three
: wires to TWO grounding screws??
Yes, technically the bare wires are "safety ground." Without seeing the
wires it is hard to guess why there are 3 instead of 4 that I would expect,
so I'll suggest a method that should work correctly whatever the reason.
Simply attach 2 bare pigtails to the 3 existing bare wires. Use a wire nut
to do this. Attach one of the pigtails to each switch at the appropriate
ground screw.
: 2) What are the dangers of leaving the bare wires as is, without connecting
: any to the grounding screws?
Likely there is very little danger, but adding a couple pigtails and hooking
them up is trivial and I highly recommend it. You could call and ask
your town or county electrical inspector. If you are just replacing a switch
it's probably not an inspection issue, but he or she will tell you what
would be acceptable by the local code. Some local codes don't like
pigtail connections, while others require them. Most inspectors I've
talked to have been reasonable and friendly if you ask questions like this.
--
*****************************************************************************
* Bill Ranck +1-540-231-3951 ra...@vt.edu *
* Virginia Polytechnic Institute & State University, Computing Center *
*****************************************************************************
Yes; at least that would be the usual practice.
|> And if so, how do I attach the three
|> wires to TWO grounding screws??
With pigtails. Run a ground wire from each switch to the bundle of ground
wires--you should end up with five wires twisted together (you may have to
use a larger wire nut).
|> 2) What are the dangers of leaving the bare wires as is, without connecting
|> any to the grounding screws?
The danger is that a hot wire could come loose and electrify part of the
switch. Most switches have few, if any, exposed metal parts; but if you
have a ground wire in the box it's trivial to ground the switch.
Hope this helps,
-Jeff j...@cray.com
--
"PHENOMENAL COSMIC POWER; itty-bitty living space." --Robin Williams in
_Aladdin_, on the pros and cons of being a Genie.
The bare copper wires are in fact grounds. They are all connected
together normally. To connect them to a grounding screw, just make
a "pigtail".
Either cut two of them shorter and twist them onto the third, which
hangs out (this is the pigtail) IF YOU HAVE ENOUGH WIRE!
Or, twist a fourth piece of bare wire about 4" long onto this set,
and connect the new one to the grounding screw.
--
Andrew L. Duane (JOT-7) du...@zk3.dec.com
Compaq Computer Corporation (603)-884-1294
110 Spit Brook Road
M/S ZKO3-3/U14
Nashua, NH 03062-2698
Only my cat shares my opinions, and she can't reach the light switches.
Ground screws on switches are almost exclusively for the situation
where the switch is installed in a plastic box. The cover screws on
a switch cover are supposed to be grounded, especially if you put on
a metal cover plate. US plastic boxes generally don't have integral
ground bounding to the switch-to-box nuts, hence, in order for the switch
body/cover plate to be grounded, you have to install a pigtail to the
switch.
In metal boxes, the switch body is grounded via the mounting bolts, so
this isn't necessary.
Though, who knows what local codes may add on...
In Canada, plastic boxes have metal bonding straps attached to the
switch mounting nuts, so, you treat them exactly the same as metal
boxes.
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Chris Lewis, CyberSheriff (CBC says I am, so it must be true!)
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>In article <6t3jhe$9rl$2...@solaris.cc.vt.edu>, <ra...@joesbar.cc.vt.edu> wrote:
>>Debbie Watson (dwa...@onramp.net) wrote:
>>: have been no problem...but I have a question about the switches. The new ones
>>: have a ground screw....the old ones do not. I get different answers from the
>>: "pros" at my home improvement stores. Here are my questions:
>>
>>The "pros" are undoubtedly making some assumptions and their answers vary
>>based on those assumptions (or perhaps their actual competence).
>
>Ground screws on switches are almost exclusively for the situation
>where the switch is installed in a plastic box. The cover screws on
>a switch cover are supposed to be grounded, especially if you put on
>a metal cover plate. US plastic boxes generally don't have integral
>ground bounding to the switch-to-box nuts, hence, in order for the switch
>body/cover plate to be grounded, you have to install a pigtail to the
>switch.
>
>In metal boxes, the switch body is grounded via the mounting bolts, so
>this isn't necessary.
>
As a former construction inspector, I would never accept grounding via
mounting bolts For one thing, these are not necessarily tightened
completely, but are left somewhat loose to allow the switch to project
the proper amount through the cover plate.
Some jurisdictions must accept this, since one can buy switches
without a grounding screw, but you won't see any in my house.
Rick Marinelli
ricklisaremo...@tidalwave.net
: Either cut two of them shorter and twist them onto the third, which
: hangs out (this is the pigtail) IF YOU HAVE ENOUGH WIRE!
: Or, twist a fourth piece of bare wire about 4" long onto this set,
: and connect the new one to the grounding screw.
I did this with my ground wires - twist all together with one longer
one going to the ground screw. In addition I added a "green" wire nut which
has a hole in it for the one longer wire. The use of this type of wire nut
for twisted ground wires is a requirement in my area.
Mark Barrett
ma...@col.hp.com