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[Mike Willis]

I'm wondering how serious this is...

Yesterday while working in a computer lab, I came across a cheap, three outlet, two-prong extension cord that had an Extron MLS 304MA AV switcher plugged in. The power cable for the switcher is grounded, so whoever plugged it in simply pried the ground at some absurd angle until the two other plugs fit the extension cord. The same extension cord also had a PC speaker and sub (no ground) plugged in.

Photo here: https://photos.app.goo.gl/mos5V77U0HUmuvcI3

What's so frustrating is that this isn't the first time I've run across this in this room. Before I start admonishing folks, I just need to know: what are the potential consequences? Damage to equipment, personal harm, etc.?

[TJ (Tom) Cornish]

I'm wondering how serious this is...

Yesterday while working in a computer lab, I came across a cheap, three outlet, two-prong extension cord that had an Extron MLS 304MA AV switcher plugged in. The power cable for the switcher is grounded, so whoever plugged it in simply pried the ground at some absurd angle until the two other plugs fit the extension cord. The same extension cord also had a PC speaker and sub (no ground) plugged in.

Photo here: https://photos.app.goo.gl/mos5V77U0HUmuvcI3

What's so frustrating is that this isn't the first time I've run across this in this room. Before I start admonishing folks, I just need to know: what are the potential consequences? Damage to equipment, personal harm, etc.?

Define "serious".  Is it likely that this is a material life safety issue?  No.  Does this fail code?  Yes.  3 prong devices need to be plugged into 3-prong receptacles.  Removing/defeating the ground pin has never been acceptable, but that doesn't mean doing so is uncommon.

An observant fire marshal may see this and ding you, but a lot of stuff like this flies under the radar.

As to the harm of this situation,  as long as there isn't another fault in the electrical system, nothing much observably bad will happen.  If however there is a fault in the Extron switcher or some other place where the metal chassis comes into contact with the hot wire (damaged cord, equipment fault, H/G reversed receptacle, etc.), that device chassis could become hot, and the safety ground would not trip the breaker, creating a shock hazard.  This condition may also damage this or other equipment sharing a ground with the Extron.

[Ray Aberle]

The other "harm" to this situation is that if someone else sees this, and doesn't know that it's a bad thing, they may do the same thing in the future. So, the risk of repetition due to ignorance is high. If you're able to find out who did it, I would def kick their butt, and explain to everyone why it's a bad idea to ever defeat safety grounds. ("And this is also something that someone ELSE should have caught and, even if they didn't do it in the first place, at least corrected the situation.")

-Ray

[Stephen Swaffer]

I think one of the big reasons for a 3 prong grounded plug on a lot of computer equipment is shielding to avoid RF/noise interference.  It could very well affect performance-and since networking using error correction, etc.  I would think it conceivable that it is affecting performance without them realizing it.

That said, you still have the safety issue of an ungrounded chassis in this case.

Unfortunately, for some the first reason might carry more weight than the second because they've done it so many times and haven't been electrocuted.

[Lyle Williams]

Describe it in a way that means something to the people responsible.

An inspector would shut down their facility.  Those with supervisory responsibilities would be held accountable.  They might get a warning or lose their job.

[Jean-Pierre Coetzee]

In this situation it looks like you would physically be able to touch both the live and neutral connector on that plug accidentally? That itself should be a "life threatening situation".

I would honestly blow it up as life threatening, honestly if there was no GFCI(GFIC???) a small fault could energize the entire chassis with 120v(240v) and cause loss of life or serious injury... IMHO that person should get a written warning(if your in that position)

[Stephen Kirby]

Many years ago I had a problem with an SMT machine that would randomly crash.  One fine day I happened to touch both the machine and the adjacent conveyor and felt a tingle.  Grabbed a meter and there was nearly 50VAC between the chassis'.  Enough that when the metal conveyors touched from vibrations that the brief spike cause something in the SMT machine to lose it's mind.  I traced it down to someone having pulled the conveyor's 110 service out of the dedicated box on the floor and inserted a cheap plastic power strip so they could also plug in a fan.  And the power strip had the ground prong broken out.
I don't know if what felt like a tingle to me touching the anodized conveyor rails (which provides some degree of insulation) might have done to someone with maybe a pacemaker getting the full effect of it.  Obviously I fixed it right away and explained to the operators and folks nearby that it was causing the machine to crash.  Since nobody had been "hurt" trying to explain the possibility to them would have gone nowhere.

[Rob Spence]

Many years ago I had a problem with an SMT machine that would randomly crash.  One fine day I happened to touch both the machine and the adjacent conveyor and felt a tingle.  Grabbed a meter and there was nearly 50VAC between the chassis'.  Enough that when the metal conveyors touched from vibrations that the brief spike cause something in the SMT machine to lose it's mind.  I traced it down to someone having pulled the conveyor's 110 service out of the dedicated box on the floor and inserted a cheap plastic power strip so they could also plug in a fan.  And the power strip had the ground prong broken out.
I don't know if what felt like a tingle to me touching the anodized conveyor rails (which provides some degree of insulation) might have done to someone with maybe a pacemaker getting the full effect of it.  Obviously I fixed it right away and explained to the operators and folks nearby that it was causing the machine to crash.  Since nobody had been "hurt" trying to explain the possibility to them would have gone nowhere.

Well, if they don't get the safety aspect, perhaps explain the production cost to the company for all the machine fails?



Sent from my iPad using Tapatalk HD

[Erik Jerde]

The ground is there for a safety reason.  Worst case, someone could die from a hot chassis that is supposed to be grounded.

[Speed Daemon]

Mike, I would focus less on how serious that one thing is, and think of it as a link in a chain--every link is important! Any link that looks weak should be repaired to protect the integrity of the whole.

Broken Windows theory says that if you let the little things that you can see now go without action, that failure to act can (and eventually does) lead to worse things. So, if you don't clear the fault that you can see, by finding a grounded extension cord for the 3-prong plug, that alone may not kill somebody. But it might be the second thing that doesn't get fixed that does kill someone...or the third. Why tempt fate? if you fix the wiring fault that you can see, you might prevent something unseen, like a bootleg ground or a hot chassis on an old guitar amp from killing someone in combination with the first.

Never count on the last safety measure to save you. Instead keep the first measure in good repair, and then the second, and then the next one...

[ProSoundWeb Community]