Reply from: Mark Voigtsberger UTGIS   July 6 2016, 11:03 am EDT
Hi Anthony,

You are correct about the GFCI nuisance tripping- it would require a pretty large and constant monitoring program, especially to make sure street lighting outages were reported and restored in a timely manner.

Several US States and parts of Canada have adopted safety testing laws as part of preventative maintenance programs to find these shock and electrocution hazards. (NY, MD, MA, RI and Ontario)

These electric faults can be detected using special sensors mounted to a vehicle to test large geographic areas quickly.

Reply from: Mark Voigtsberger UTGIS   June 15 2016, 10:46 am EDT
Hi Todd,

This is a tough question. As electricians or electrical workers, we hope all our training and PPE will prevent us from ever being in such a situation- but the reality is, it happens.

Reply from: Mark Voigtsberger UTGIS   June 15 2016, 12:18 pm EDT
Hi Bruce

I just sent Mike a chart that should answer your question. I do not know what your term "electrical contact" means.....but took a stab in the dark and considered it to mean "electrical shock".

Under a soon to be approved IEEE Standard (1695, Guide to Understanding, Diagnosing and Mitigating Stray and Contact Voltage) there is no formal distinction between voltage potential levels that produce shocks and those that produce electrocutions as it applies to "Contact Voltage". Human shocks and electrocutions due to Contact Voltage is what this newsletter is about, although we did not use the term in the write up. In many cases where a public electrocution has occurred, others have come forward and stated they had received an electrical shock on that same object. This is why our data was combined in the original chart on this newsletter- what is a shock to one person could take the life of another.

I disagree with you on one point: "The combination of these two distinct areas of electrical contact are typically done to over-emphasize the seriousness of the problem".

Generally, people (meaning pedestrians) do not report electrical shocks if they or their dog gets a little tingle from an object like a light pole- they simply go on their way.

Mobile scanning of cities by myself and other firms find very large numbers of publicly accessible objects with contact voltage potential on them. 30+ energized objects per night is normal. Some are at full phase voltage, but many are 1-5 volts. Almost all of these could produce a shock or electrocution under the right conditions, but when cross referenced, none were reported to 911 or 311 call centers.

Because public electrocutions usually make the local or national news, we believe those numbers to be somewhat accurate.

When looking at the number of public electrical shocks due to contact voltage, we believe that number to be greatly under reported.

Based on actual field testing, the number of found publicly accessible objects with voltage potentials high enough to shock or electrocute a human is substantially higher than the cases reported in the attached chart.

Hope this addressed your questions,

Mark

Reply from: David Rifkin   June 15 2016, 12:42 pm EDT
As with Electric Shock Drowning it all depends. Generally a voltage gradient of about 2v/ft in the water will cause enough current to flow through a "nominal" person to cause paralysis (10-12ma). But it varies by person (skin type, fat layers, surface area, skin condition, etc).

Will some people survive a 2v/ft gradient? Yes. Could a 1.5v/ft gradient cause paralysis in some people? I think so.

For the same touch voltage, the resistance from this point to ground (the path the dangerous shock current will take) determines the magnitude of current in the body. Bare feet or rubber soled shoes? Wet floor or dry floor? The current level then determines the physiological effect on a particular individual.

Maybe this is why they don't break out the touch voltage level in the electrocution data. It likely happens at a wide array of voltages.