Grounding Guard for Light Fixture (01-25-2K)
Our company recently received an electrical citation for the following circumstance: A 60-watt light bulb was mounted in a porcelain, single-bulb fixture. Attached to the fixture was a metal light bulb guard. The inspector claimed that the situation was a hazard, because the metal guard was not grounded. The citation was abated (ended) by attaching a ground wire from the guard to a mounting screw on the fixture
My question: Was this situation a hazard to persons, and is there anything in the NEC that requires such grounding of light bulb guards? We are under MSHA jurisdiction, and MSHA standards contain no such requirement for the grounding of light bulb guards. The inspector cited us under CFR 30 57.12030, which states, "When a potentially dangerous condition is found it shall be corrected before equipment or wiring is energized." Again, was this a potentially dangerous situation? Our head electrician doesn't think so, and I am curious. Can any of the newsletter members give me some feedback?
Johnie Brake, firstname.lastname@example.org
Response No. 1:
Typically any metal "likely to become energized" must be bonded to ground. In my experience "likely to become energized" is interpreted to mean everything near energized circuits, anything electrical. So I'm not surprised at the inspector's call. I am somewhat surprised that the guard did not come with a ground strap already on it.
Response No. 2:
If something hits the guard with enough force, the guard will bend, the lamp will break, and there is a good possibility the guard will touch one of the filament conductors. When someone goes to repair it, the guard will be energized. I think MSHA inspector is right.
Eric & Carrie Brown
Response No. 3:
Since you are in mining, one can throw out anything "normal" as in other industries. One has to know all the particulars in this case, as there are probably considerable mitigating circumstances. Was it outside or in a wet location, or what was the height from the walkway or work platform? Also, you might want to check out the standard MSHA 56.12025, as this is probably the standard that should have been cited in the first place.
Response No. 4:
Article 410-20 states: "fixture with exposed metal parts shall be provided with a means for connecting an equipment grounding conductor for such fixtures." I never thought of the dangers of a nongrounded wire guard but can't argue the reasoning behind it. Think of a situation where someone hits the guard and smashes the lamp and guard and the lamp element is now in contact with the guard that's insulated from a grounded surface----results are you have an exposed metal guard with line voltage on it. Now, someone comes along ---? No light! Lamp must be burned out? Reaches up to find energized exposed metal guard. This could be a dangerous situation. Again, I've never thought about it but can't argue when safety is the issue!
We just had a 14-year-old boy electrocuted on a tennis court light pole. The paper reported that the electrical inspector looked at the pole and light fixture and found bare exposed wires in the fixture but it was "normal wear and tear"---like what is going on here----the issue is "why wasn't the pole grounded"? Someone will find out why, and someone will get sued, but life will never be the same for the boy's family!
Response No. 5:
The Code (Article 250) states that metal objects that are likely to become energized and present a hazard shall be bonded to equipment ground. It does not seem that it is likely to happen in this case. What would energize the guard? Article 410 states that exposed metal parts of light fixtures must be grounded or insulated from ground and other conducting surfaces or inaccessible to unqualified personnel. OSHA allows exposed live parts on light fixtures if they are 8-feet or more from floor level. This is in 1910.305 j.
The final check would be to read the installation instructions for the guard. If it is UL listed and you follow the manufacturer's instructions, you should be in the clear. Unless there is a fine involved or many fixtures to repair, I would just bond the guard like you did; it's less energy spent.
Richard Currin, email@example.com
Response No. 6:
I can see why the inspector wanted the guard grounded. If the glass of the bulb shatters (breaks) and the filament or wires inside the bulb come in contact with the guard, it will become energized. One way out of this problem is to use a plastic guard.
Bill Hopka, www.troubleshooterelectric.com
Mike Holt's Comment: The NEC does not appear to directly address this issue.
410-17. Fixtures and lighting equipment shall be grounded as required in Article 250 and Part E of this article.
Comment: Article 250 states that exposed noncurrent-carrying metal parts of fixed equipment likely to become energized shall be grounded.
410-18(a). Exposed metal parts shall be grounded or
insulated from ground and other conducting surfaces or inaccessible to unqualified personnel.
Comment: One could argue that the metal guard is insulated, therefor it is not required to be grounded.
However, after reading all of the comments, I would insure that the guard is grounded or better yet, I would use a plastic guard.