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Joined: Aug 2007
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I have seen alot of what you describe Kjay, I always use metal boxes on the metal studs. Perhaps just my Industrial/commercial background. Habit more than anything else. Lee, do you recall seeing anything regarding bonding metal stud walls in the MA building Code? I was at a seminar several years back and this came up, but I haven't heard anything about it since. TKX Nope. Last I heard was the big to do over "Victolic" fittings. That vanished as well.
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Joined: Mar 2009
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I think the language adopted by Florida in re: bonding metal studs would be a good addition to the next NEC revision. Pretty simple, pretty cheap, and would eliminate the risk of energizing a metal studded wall section. Just require one metal, grounded box attached to each partition/section, thus grounding the whole section. That should be pretty cheap to implement, and, as the news story about the tragic death of the dryer installer demonstrates, this is an issue occasionally.
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Joined: Jul 2004
Posts: 9,928 Likes: 34
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It is even easier than that. Just change the listing standard for plastic boxes, meant for metal studs to include a bonding lug for the metal mounting strap.
It could be as simple as a "stab" into a lip that goes into the box.
Greg Fretwell
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I guess I'm not concerned with the metal studs inside a wall. At the risk of suffering the wrath of the members of this group, and given the subjective words "likely to be energized" I would not have a contractor bond the metal studs at all. Is there any track record of a problem? I say if the wiring method is installed properly, the likelihood of a problem is not there.
George Little
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I would say that the unfortunate dryer installer's death constitutes a compelling 'track record of a problem.' While the problem (electrifying the studs) requires some very unusual circumstances to manifest itself (errant drywall screw piercing an improperly installed piece of romex), the risks are sufficiently grave to justify a regulatory response. All metal studs should be grounded. This is easily done, either with a metal box or jumper of some sort. From a cost/benefit perspective, it is a low cost/high benefit situation.
Last edited by Bigplanz; 03/19/09 12:49 PM.
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Joined: Jul 2004
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George, If this segment of wall was truly isolated, with no way anyone could contact an energized part of it I might agree there is little hazard, until someone drills into a stud with a screw to hang something heavy. At that point you have brought the hazard into the room.
In the Florida incident it was the metal dryer vent enclosure that was screwed into the steel studs. It could have easily have been a metal medicine cabinet or a sliding glass door/window frame.
Last edited by gfretwell; 03/19/09 03:11 PM.
Greg Fretwell
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Joined: Mar 2009
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If you click the link and click on the 'video' tab you will see the news segment that ran on TV about the dryer installer's death. In the segment, there is an electrician testing the medicine cabinet and getting a reading of 120V. The little dry wall screw that barely pierced the romex created quite a hazard. I would think, code requirement or not, it would be a 'best practice' in the trade to bond a metal stud wall with electric wires running through it.
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Joined: Jan 2004
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Did you guys happen to notice the word "Bazaar" or did you notice that the wires were not properly installed? I'm saying that things like this happen no matter what the code says or how we try to avoid them. We have inspectors who want the I beams bonded because they are "likely to be energized" because wires pass over them. I think bonding the metal studs inside a wall is right there with paranoia. Send in a proposal and see how far it goes.
George Little
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It was quite a 'bizarre' accident, and unlikely to be repeated in exactly that way. However, it certainly does prove it is a potential hazard to leave metal studs ungrounded. Regrettably, improperly installed wiring is all too common in residential construction, and all too commonly overlooked at the inspection stage. The improper step here appears to be the romex was not clipped or connected as it should have been under code, thus was too close to the drywall. When the screw was driven in, just the point pierced the romex, thus creating the short that energized the studs. This wiring error would be easy to overlook, and evidently was overlooked at the rough-in inspection. To further compound matters, it was passed even at the final inspection, two weeks after the man was killed. Hard to know what make of that one.
In any event, quite a few code provisions are included to deal with unlikely events. It seems to me that since there is very little, if any, cost associated with bonding a metal stud partition, and the risk of electrocution certainly is present in worst case circumstances, why shouldn't it be a code requirement?
You might want to contact the widow of the man killed and ask her if perhaps it is paranoid for anyone to be concerned about this hazard.
Last edited by Bigplanz; 03/19/09 06:33 PM.
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Joined: Jan 2005
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My,my, the rhetoric is getting thick!
While I'm sorry the guy died, let's not overlook thefact that several things 'went wrong,' and that existing rules were violated.Passing new rules only affects those who follow them!
Track record? I think not ... 'freak accident' seems more appropriate.
There is a limit to "practical" safeguarding.
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