ECN Forum Forums General Topics of the Trade General Discussion Area wrong polarity

As Tex said, they use non-polarized plugs in most of Europe, and even in countries like France where grounding-type plugs ARE polarized, there's still not much concern over which way hot & neutral are wired to a receptacle.

These days in this part of the world, everything from toasters to electric drills to computer printers are sold in basically the same model right across Europe, so they're designed so that polarity is unimportant. A lot of power tools are now fitted with a double-pole switch as well.

I think you'll find some older radio/audio equipment made in the U.S. (perhaps 1960s or earlier) which had an ungrounded cord and used a high-value resistor (1 meg up) or a small capacitor direct from neutral to casing. Swapping H&N on one of those could result in some tingles, especially if the cap has gone leaky with age.

Redsy: I checked and found the following article in the November issue of EC&M. You mentioned that I might be able locate it -- here it is: Look under Forensic Case Book

Mother Electrocuted By Pressure Washer

By Kenneth E. Buske, P.E., Buske Engineering

Electrical Construction & Maintenance, Nov 1, 2001


http://industryclick.com/magazine.asp?magazineid=31&siteid=13&releaseid=9603


[This message has been edited by Joe Tedesco (edited 01-12-2002).]

Oops, I did something wrong. http://industryclick.com/magazinearticle.asp?magazineid=314164&siteid=13


[This message has been edited by electure (edited 01-12-2002).]

Cindy,
While an amprobe may be valuable, especially if you can take some voltage readings, it may be as useful to take one of those "pen type" voltage detectors with you. This would be a bit more surreptitious, and they are quite a bit more concealable. My guess is the owners of this salon would not like you experimenting on their equipment, especially if you're going to expose a hazard.

thanks for all the information again.
guess a gfci would have saved that woman, if plugged into the garage or outside.. wonder if the afci would have done anything, guess it wasnt really an arcing fault so probably not.
on the tan bed frame, the amprobe bounced around 2 volts from one side of the bed to the other. stings and still makes you nervous, but guess i'll live.. maybe die of skin cancer first

The incident in the article had a number of factors, either of which if not present, would likely have prevented an electrocution. The pressure washer had a puncture in the insulation on the neutral then came in contact with the frame. The ground prong on the cord was cut off, but it was also a non-polarized plug, either safety feature individually could have prevented her from inserting it into the receptacle backwards. Finally, she plugged it into an indoor receptacle which was not GFCI protected. Hard to believe this sequence of events played out the way it did.
Proper polarity is indeed a critical safety, if not functional, consideration.



[This message has been edited by Redsy (edited 01-12-2002).]

A story about hot/ground reversed came to my mind. It happened a few years ago here in Austria, and I can't remember the exact details. However it was about the following: A guy repaired or built his own pool. When working at the pump he reversed hot/ground. Then he jumped into the pool. His wife saw him, thought he fainted and jumped in too. Their som saw them, but was bright enough to switch off the power. I think they survived, but I'm not sure.

Eek! Nasty...

Was that due to some sort of confusion with the old "red = ground" color coding there?

I have no idea about that. All i know is from a very short newspaper article about 6 years or so ago.
However what about that power washer story?
It says that using a polarized plug would have saved that woman. In this special case it's true, but in any other the insulation of the hot wire could have been faulty too, in that case it'd have actually saved that woman. I thought this is something to think about.
I agree that the missing ground prong was really dangerous.

There may be a good reason to prepare a new proposal to be sent in for consideration in the 2005 NEC. I found the following related to "reverse polarity" and offer it here for discussion.

See NFPA 302 Fire Protection Standard for Pleasure and Commercial Motor Craft 1998 Edition

Section 8-7 Shore Power Polarity Devices.
8-7.1*

Reverse-polarity indicating devices having a continuously visible or audible signal shall be installed in 120 VAC shore power systems, provided the following applies:
(a) The polarity of the system is maintained for the proper operation of electrical devices in the system
(b) A branch circuit is provided with overcurrent protection in the ungrounded current-carrying conductors only
Exception: Systems with polarization or isolation transformers that establish the polarity of the onboard system.

A-8-7.1
Reverse-polarity indicating devices should respond only to reversal of the ungrounded conductors and the grounded (white) conductor where there is continuity of the grounding (green) conductor to shore.
Reverse-polarity indicating devices should not be required to respond to reversals of the ungrounded conductors and the grounding (green) conductor, the grounded (white) conductor and the grounding (green) conductor, or to reversal of three-phase conductors.