Red Warning Lights on Dock Transformers

Members of the Vessel Electrical committee are often ask what the red light means on top of the dock power transformers and should that be of concern. The simple answer is YES, with some understanding. The red lights mean that at least one or more boats in this area probably have electrical problems which could be dangerous to someone falling in the water. Should you see a red light, please tell a Bridge Officer.

The following provides a bit of knowledge as to the why the Club invested in this technology and what the red light indicates.

Due to the frequency of deaths from electric shock drowning, the US Coast Guard was called on to conducted analysis of the effects of AC electricity on the human body when immersed in water. The amount of current in these situations is normally discussed in milliamps, which is one thousandth of an amp. A 100 watt lightbulb uses approximately one amp, so we’re discussing very minute amounts of electricity.

Whether it’s salt or fresh water, roughly 30 milliamps of stray AC current will induce muscle spasms impeding the ability to swim and breathe, with drowning as the eventual outcome. At a slightly greater level, 100 milliamp exposure will instantly stop the heart from beating.

There are three transformers on each dock serving the shore, middle and water side segments respectively and each one has its own current meter. The red lights in question are attached to those current meters which sample all the boats served by that transformer every second, around the clock. Those meters look for a current imbalance that could indicate electricity leaking into the water. Each meter is set to “alarm red”, when the current imbalance for that dock section exceeds 100 milliamps (heart stopping).

Does this mean that should you fall in the water in an area alarming red, that you will be immediately electrocuted? Probably not due to a number of factors, but it is a clear warning there is some electrical issue within those approximately thirty boats that merits investigation.

Is my boat causing the problem? Every mooring member can conduct a conclusive test to answer that question, without fear of getting shocked or breaking something. Hanging on the wall inside Cummings Hall is an “Equipment Leakage Current Interrupter” (aka ELCI) cord. It looks like a three foot long shore power cord, with a circuit breaker in the middle (and has a tender fender cabled to it). This can be used by any mooring member to test their boat. Simply turn off your pedestal breaker, plug the ELCI device into the pedestal and your shore power cord into the ELCI. Turn on the pedestal power, turn on the ELCI breaker (a little indicator light will glow), then turn on all onboard breakers. Your vessel is OK if the ELCI cord stays on throughout the test. If it disconnects, you’ve got an onboard electrical problem and should contact a qualified marine electrician.

The club’s vessel electrical inspection program is a very proactive program to address these concerns. The entire membership is commended for their willing participation in the program and the quick response to correcting deficiencies.

Thanks for the inquiry. The QCYC Vessel Electrical Committee appreaciates all questions from the membership.