‘WIRED FOR SUCCESS’
It’s time to dive into the electrifying unknown with our new column featuring Reuben Clark, the wizard of wires in pool service! Reuben is here to illuminate the path to a safer, more efficient, and expertly-wired outdoor oasis.
Reuben Clark has been the President and cofounder of Consolidated Manufacturing International, LLC (CMI) for more than 22 years, developing and manufacturing electrical products for the pool industry. Reuben holds an MBA, is a member of the IAEA, NCEIA, and NFPA, and has been involved in development of the National Electrical Code. He lives in Raleigh, North Carolina with his wife and has three grown children.
Let Reuben’s expertise shed light on everything electrical from the complexities of bonding and grounding to electrical code compliance and troubleshooting issues.
Send your questions to info@serviceindustrynews.net.
After reading my last column extolling the benefits of low-voltage lights for pools and spas, someone sent in the following statement and question: “You hear time and again that it is the current that kills — not the voltage. So, are low-voltage lights safer than standard pool lights, and if so, why?”
The short answer is the higher the voltage you expose a human to, the higher the current through the body path. 120V is going to push ten times the current 12V will.
Most agree that the resistance of a human body submerged in water is about 300 ohms from head to foot. Therefore, a 120V/300ohm = 40 milliamps of current through the body from a 120V faulted light, where 12V/300ohm = 4 milliamps of current through the body from a 12V faulted light.
The UL Standard for a GFCI to trip is between 4-6 milliamps. Muscle lock can occur in the human body when exposed to 16-20 milliamps, and breathing paralysis can occur around 30 milliamps. This illuminates (pun intended) the difference of possible damage between a lowvoltage 12V lighting system and 120V. The low-voltage fault current is at such a low level that it may not trip a GFCI function, while the 120V could cause breathing paralysis.
One recent theory presented by forensics when investigating unexplained drownings is temporary stray or contact voltage. The voltage is strong enough to cause muscle lock while in the pool, and the swimmer is unable to keep their head above water, thus drowns. The voltage was not strong enough to leave a physical trace on body such as a burn of the skin, so there is nothing to indicate it was present. The fact that it was temporary means it more than likely will not be present when forensics investigate. Therefore, the cause of death was drowning, but the reason for the drowning was temporary stray or contact voltage.
The long answer to why lowvoltage lights are safer than standard 120V is very complicated, difficult for most people to understand, and is not easily found. When I began research to see what was available publicly, primarily online, I could not find anything more than was written in my last article. No physics, math, or biology was used to explain any of it.
One of my colleagues, who is an expert in the field of stray and contact voltage, told me that even people in the industry confuse the two most common situations with voltage in pools. The first is someone completely in the water, versus the second is someone contacting the deck or metallic handrail with one part
Today’s Topic: Low Voltage Lights:
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of the body while another part was in the water. These are two completely different problems, and the problem with underwater lighting is the first situation. The “short answer” written at the beginning of this article should provide a basic understanding as to why low-voltage lights are safer than 120V, when considering the effect of current on the human body.
Protecting swimmers in the pool, spa, and on the deck can easily be accomplished with proper equipotential bonding planes. Proper bonding of the pool system is of paramount importance but can be overlooked or ignored because the danger is unseen and thus potentially unrecognized.
