bphgravity
Senior Member
- Location
- Florida
Re: why cut off the grounds?
If you read the sections concerning the grounding of faceplates and enclosures for switches over the last few code cycles, you can reason out the intent and need for switch grounding (bonding).
In the 96' code, if you mount a switch in an ungrounded box and the wiring method has no egc, a metal faceplate can't be used if in reach of conductive surfaces. Obviously, the intent is to ensure that a failure of the device or the terminations does not energize the plate which is accessible to persons. However, what happens later down the road when someone replaces the plastic plate with a metal one?
This is issue is considered in 99' code. 380-9 then required the the switch to be grounded by one of the approved methods. It still appears the intent is for providing a means to ground metal faceplates if they are installed. In this edition, the exception allows the use of a nonmetallic plate where grounding means don't exist instead of being the main rule.
The 02' edition didn't make a siginifcant change and nor has the 05' other than the exception now permits the switch to have gfci protection if a grounding means is not present.
So in effect, it appears the concern is with persons in contact with conductive parts while standing on conductive surfaces. At one point, the soultion was to simply not use metallic plates. Now, it appears we ground switches for the purpose of potential use of metal faceplates and provide alternatives to grounding the switch while still limiting the exposure to persons.
On a side note, this is a prime example of why the term grounding is not an appropriate term when we are actually describing bonding.
If you read the sections concerning the grounding of faceplates and enclosures for switches over the last few code cycles, you can reason out the intent and need for switch grounding (bonding).
In the 96' code, if you mount a switch in an ungrounded box and the wiring method has no egc, a metal faceplate can't be used if in reach of conductive surfaces. Obviously, the intent is to ensure that a failure of the device or the terminations does not energize the plate which is accessible to persons. However, what happens later down the road when someone replaces the plastic plate with a metal one?
This is issue is considered in 99' code. 380-9 then required the the switch to be grounded by one of the approved methods. It still appears the intent is for providing a means to ground metal faceplates if they are installed. In this edition, the exception allows the use of a nonmetallic plate where grounding means don't exist instead of being the main rule.
The 02' edition didn't make a siginifcant change and nor has the 05' other than the exception now permits the switch to have gfci protection if a grounding means is not present.
So in effect, it appears the concern is with persons in contact with conductive parts while standing on conductive surfaces. At one point, the soultion was to simply not use metallic plates. Now, it appears we ground switches for the purpose of potential use of metal faceplates and provide alternatives to grounding the switch while still limiting the exposure to persons.
On a side note, this is a prime example of why the term grounding is not an appropriate term when we are actually describing bonding.
Being originally from N. Cal and after K&T, lights are powered from the switch box to ceiling switch legs or half-hots since I remember. Bonding a grounding connection was code in 72, so cutting at the sheath was a violation then even without switch ground terminals. At least a half dozen shops I know of all stowed those bare wires.(That was in 3 different countys.)