# Grounding Switches



## dglass4321 (Apr 16, 2017)

We started a refresh of our 22 year old kitchen.  We are having the cabinets refinished, new appliances, LED lighting and new flooring.  I'm replacing the old white outlets and switches with black ones to compliment the granite.  I'm finding that all the new switches have a ground screw.  Why is this necessary?  I understand about grounding outlets but why switches?  It seems like it is unnecessary since a switch isn't a complete circuit.


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## slownsteady (Apr 16, 2017)

Not the classic scientific answer, but since there is current present, there has to be a way to ground it. And AFAIK all components (fixtures, boxes, etc.) need to be grounded throughout the circuit.


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## Snoonyb (Apr 16, 2017)

Every switch has a hot lead connected to it.

Between melamine and plastic boxes, there were metal boxes and there was a ground connection through the metal frame of the switch, the screw to the box, however this only worked if the box was bonded and/or there was a grnd. conductor present.

So, plastic boxes, wet hands=murphy's law. Code are designed to protect you, from you.


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## dglass4321 (Apr 17, 2017)

I can understand all of that but I guess I was unclear on the topic.  I neglected to mention that none of the old switches had grounding lugs.  I installed them myself 22 years ago when we built the house.  And they aren't an odd brand; they are Levitron Decora switches that I bought at Home Depot and they do not have grounding lugs.  Obviously during the past 22 years it became a requirement.  What is frustrating is that very few of the switch boxes have a ground wire present and the boxes are plastic so what am I supposed to ground to!


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## nealtw (Apr 17, 2017)

You could add a short piece of wire but also take note that the box has a piece of steel that runs up one end to connect the ground to the switch when the switch is screwed in place.


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## Snoonyb (Apr 17, 2017)

dglass4321 said:


> I can understand all of that but I guess I was unclear on the topic.  I neglected to mention that none of the old switches had grounding lugs.  I installed them myself 22 years ago when we built the house.  And they aren't an odd brand; they are Levitron Decora switches that I bought at Home Depot and they do not have grounding lugs.  Obviously during the past 22 years it became a requirement.  What is frustrating is that very few of the switch boxes have a ground wire present and the boxes are plastic so what am I supposed to ground to!



If there is no grnd conductor present, then you just ignore it, because you cannot and are not required to correct the uncorrectable.


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## nealtw (Apr 17, 2017)

Snoonyb said:


> If there is no grnd conductor present, then you just ignore it, because you cannot and are not required to correct the uncorrectable.



House 22 years old, has a ground.


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## Snoonyb (Apr 17, 2017)

nealtw said:


> House 22 years old, has a ground.



From post #4; "What is frustrating is that very few of the switch boxes have a ground wire present and the boxes are plastic so what am I supposed to ground to!"


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## nealtw (Apr 17, 2017)

Snoonyb said:


> From post #4; "What is frustrating is that very few of the switch boxes have a ground wire present and the boxes are plastic so what am I supposed to ground to!"



If the original switches didn't have a ground screw it would be reasonable for some one to wrap the screw in the box and cut the extra wire off. Then the ground strap will do the job.
If there is no ground there, non of this will matter much.


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## slownsteady (Apr 17, 2017)

q1: so 22 years ago, you installed plastic boxes?
q2: is there a bare ground wire in the wire runs (white, black, bare or green)?


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## Snoonyb (Apr 17, 2017)

slownsteady said:


> q1: so 22 years ago, you installed plastic boxes?
> q2: is there a bare ground wire in the wire runs (white, black, bare or green)?



See post #4.


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## bud16415 (Apr 18, 2017)

The only metal you come in contact with given a plastic cover plate is the heads of the screws that hold the cover on. They are threaded into the steel frame of the switch. In the unlikely event the power shorted to the frame a safety ground wire connected to the switch would make a path to ground and trip the breaker. If a metal box was used and it was grounded there would be no need for the ground wire as the metal frame is attached to the box. 

If it were mine and I had the safety ground in the cable I would attach it. If I was replacing the switch and it was old work and no ground was there I wouldn&#8217;t give it a second thought and just hook it up like the old one.


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## nealtw (Apr 18, 2017)

bud16415 said:


> The only metal you come in contact with given a plastic cover plate is the heads of the screws that hold the cover on. They are threaded into the steel frame of the switch. In the unlikely event the power shorted to the frame a safety ground wire connected to the switch would make a path to ground and trip the breaker. If a metal box was used and it was grounded there would be no need for the ground wire as the metal frame is attached to the box.
> 
> If it were mine and I had the safety ground in the cable I would attach it. If I was replacing the switch and it was old work and no ground was there I wouldnt give it a second thought and just hook it up like the old one.



Have another look at plastic boxes.
https://www.google.com/patents/US3119895


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## bud16415 (Apr 18, 2017)

nealtw said:


> Have another look at plastic boxes.
> https://www.google.com/patents/US3119895



Its great someone patented one in 1968 but all the ones I have bought are all plastic expect for the two nails you use to attach them to a stud. When I go to the apron and vest stores they have barrels of the all plastic blue ones. 

Seems simpler to just ground the outlet or the switch and my guess is thats why they added the ground screw to the switches.


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## Snoonyb (Apr 18, 2017)

nealtw said:


> Have another look at plastic boxes.
> https://www.google.com/patents/US3119895



Or these most commonly used today;http://www.homedepot.com/s/electrical+box?NCNI-5


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## nealtw (Apr 18, 2017)

Snoonyb said:


> Or these most commonly used today;http://www.homedepot.com/s/electrical+box?NCNI-5



There you go, I have not seen a plastic box with out ground strap, but it looks like they are not in that picture.


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## Snoonyb (Apr 18, 2017)

bud16415 said:


> Its great someone patented one in 1968 but all the ones I have bought are all plastic expect for the two nails you use to attach them to a stud. When I go to the apron and vest stores they have barrels of the all plastic blue ones.
> 
> Seems simpler to just ground the outlet or the switch and my guess is thats why they added the ground screw to the switches.



And there are a number of unknowns like, what is the dwellings age and in the boxes that do not appear to have a ground conductor, could it be in a romex that didn't have a grnd conductor or in the evolution of romex when an 18ga. bare copper was included and as often as not, simply cut off close to the strip.


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## Snoonyb (Apr 18, 2017)

nealtw said:


> There you go, I have not seen a plastic box with out ground strap, but it looks like they are not in that picture.



Every home desperado, low brow and ace have them.


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## nealtw (Apr 18, 2017)

Snoonyb said:


> Every home desperado, low brow and ace have them.



Up here they have a strap like this one
https://www.homedepot.ca/en/home/p.one-gang-plastic-device-box.1000404475.html


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## Snoonyb (Apr 18, 2017)

I now understand your point of reference.

Mite be a long drive, from PA.


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## nealtw (Apr 18, 2017)

Maybe a code thing up here.


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## nealtw (Apr 18, 2017)

dglass4321 said:


> We started a refresh of our 22 year old kitchen.  We are having the cabinets refinished, new appliances, LED lighting and new flooring.  I'm replacing the old white outlets and switches with black ones to compliment the granite.  I'm finding that all the new switches have a ground screw.  Why is this necessary?  I understand about grounding outlets but why switches?  It seems like it is unnecessary since a switch isn't a complete circuit.



Because you could have a problem with the switch that made the steel frame of the switch live so when you touch the cover plate screw you get 120 volts.
If the switch is grounded. the breaker would pop at the first site of a problem.


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## bud16415 (Apr 18, 2017)

nealtw said:


> Because you could have a problem with the switch that made the steel frame of the switch live so when you touch the cover plate screw you get 120 volts.
> If the switch is grounded. the breaker would pop at the first site of a problem.



Thats what I said in #12. 

I havent taken a switch apart in many years but I doubt there is a failure mode that would energize the frame of the switch. Your 120V electric drill doesnt even have a ground as they call it double insulated. 

I have a few old switches laying around I will have to pry one open and see if any failure mode could cause a frame to go hot.


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## dglass4321 (Apr 18, 2017)

nealtw said:


> House 22 years old, has a ground.


 I didn't say the house wasn't grounded, if you read my post I said the switches weren't grounded.  All of the outlets and fixtures are properly grounded.


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## dglass4321 (Apr 18, 2017)

slownsteady said:


> q1: so 22 years ago, you installed plastic boxes?
> q2: is there a bare ground wire in the wire runs (white, black, bare or green)?


 
We had a contractor do the rough in of the electrical. Yes, he used plastic boxes (and no, they don't have a grounding straps) I did all the finish wiring and installed the fixtures.  What we have is one black wiring coming in to the box and one black wire exiting the box.  In some cases there are additional wires to accommodate three way and four way switches.  If there was a bare ground wire, as there is in the outlet boxes, this would be a non issue because I would have something to ground to.


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## nealtw (Apr 18, 2017)

bud16415 said:


> Thats what I said in #12.
> 
> I havent taken a switch apart in many years but I doubt there is a failure mode that would energize the frame of the switch. Your 120V electric drill doesnt even have a ground as they call it double insulated.
> 
> I have a few old switches laying around I will have to pry one open and see if any failure mode could cause a frame to go hot.



I was just stating why the ground is there not the probability of failure.


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## nealtw (Apr 18, 2017)

dglass4321 said:


> I didn't say the house wasn't grounded, if you read my post I said the switches weren't grounded.  All of the outlets and fixtures are properly grounded.



Yeah I get it, just stuff I have never seen.:rofl:


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## afjes_2016 (Apr 19, 2017)

Long time ago when I took my electrical classes I read something about the fact that if switches had "metal" face plates the switches must be grounded. But nowadays very few people use metal face plates in their homes.

I would not consider this to be a big safety factor at this point. Although it is possible to get a "zap" from the small screw head on the face plate even if the face plate is plastic.

You know the good-old NEC; it was developed mainly from safety/non safety incidents that have happened in the field in the past and then precautions are written into the code when they feel it is time to to prevent the accidents that have occured in the past.


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## hornetd (May 16, 2017)

The code is written to provide an installation which is "essentially free from hazard."  

90.1 Purpose.
(A) Practical Safeguarding. The purpose of this Code is the practical safeguarding of persons and property from hazards arising from the use of electricity.

If the box is metal then you can ignore the ground screw on the switches strap or yoke.  If the box is non metallic and there is an Equipment Grounding Conductor (EGC) available in the box the green screw with the hexagonal head provides a place to bond the EGC to the strap or yoke of the switch.  If the strap or yoke of the switch is connected to ground then the use of a metal cover plate; either now or in the future; will not expose the occupant to the possibility of contact with a surface which has been energized to 120 volts to ground.


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