9-96 Log #2248 NEC-P09 Final Action: Accept in Principle
(404.9(B)(1))
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Submitter: Joseph Penachio, Joe Penachio Electrician
Recommendation: Revise as follows:
(B) Grounding. Snap switches, including dimmer and similar control switches,
shall be effectively grounded and shall provide a means to ground metal
faceplates, whether or not a metal faceplate is installed. Snap switches shall be
considered effectively grounded if either of the following conditions is met.
(1) The switch is mounted with metal screws to a metal box or device
extension, raised cover that is secured to the box with a minimum two 8/32 in.
screws and is in direct metal to metal contact to the box, or to a nonmetallic
box with integral means for grounding devices.
(2) An equipment grounding conductor or equipment bonding jumper is
connected to an equipment grounding termination of the snap switch.
Substantiation: A 4 in. square blank cover is not required to have a bonding
jumper installed to ground it to the box because it is considered effectively
grounded by being secured by two screws and having metal to metal contact
between the box and the cover. In fact, there is more yoke contact to a raised
cover than there is from a yoke to a handy box which is allowed as metal-to-
metal contact. Being secured by two 8/32 in. screws the extension or raised
cover are electrically and mechanically secure. Removing the cover with the
switch on it does not pose any danger to a qualified person than if there were a
jumper installed.
Panel Meeting Action: Accept in Principle
Revise 404.9(B)(1) as it is incorporated within Proposal 9-18 by adding the
words “or metal cover” after the words “metal box” and before the words “that
is connected to an equipment grounding conductor …”
The final text of 404.9(B)(1) will read as follows:
(1) The switch is mounted with metal screws to a metal box or metal cover
that is connected to an equipment grounding conductor or to a nonmetallic box
with integral means for connecting to an equipment grounding conductor.
Panel Statement: The panel action meets the objectives of the submitter, who
correctly pointed out the absence of coverage for snap switches mounted in
raised covers. As in the case of receptacles in raised covers, the requirements for snap switches are less severe than those for receptacles.
Number Eligible to Vote: 11
Ballot Results: Affirmative: 9 Negative: 1
Ballot Not Returned: 1 de Vega, H.
Explanation of Negative:
BELISLE, R.: The proposed action and statement by the panel allows for
switches mounted in raised industrial covers to be grounded via the cover,
therefore exposing the electrician to a shock hazard when mounting screws
become loose, the cover is removed to service the device, take test
measurements, or other activities OSHA would allow while energized.
Installation of a bonding jumper to the box from the device is a small request
in exchange for a safe installation. See my statement for proposal 9- 95 also
regarding the effective grounding of a switch.