Tuesday, July 24, 2018

Electricity, ESD, and Your Dock

According to a 2014 CDC report, an average of 3,536 people per year die from accidental drowning unrelated to boating  This is basically an accounting of people drowning just swimming in the water and there are many reasons such tragedies occur but one contributing factor is electrocution, or Electric Shock Drowning (ESD). Just how many of these non-boating related drownings can be attributed to electrocution while in the water is harder to know since ESD statistics are not as carefully documented, but we do know it happens and sadly the Lake of the Ozarks has had its share. Homeowners need to start taking action now to prevent their docks from being a danger to themselves, their families and their neighbors. Making sure your dock is as safe as possible is not only a responsibility, it may soon become mandatory.

Is ESD a new phenomenon, or does it just seem to be happening more often? Electric service on docks is nothing new, but it has become far more commonplace. The need for boat lifts, and the general trend to make living space on our docks has meant more and more power is being delivered over the water. On the other hand, our interconnected world and social media has made awareness of these types of tragedies more prevalent. These two factors, I believe, have both raised the risk and the awareness.

Can we eliminate the risk of ESD? Sure, by mandating that there can be no electrical service on docks. Period. Sound good? Believe it or not there are those that advocate such measures, namely the ESD Prevention Association which believes that docks and marinas should not have electricity and promote awareness to not swim anywhere near ones that do. Others suggest a less radical but inconvenient idea of turning off power to the dock before swimming near it. The main problem with this idea is that it relies on the most unreliable safety feature in any given system, a human being. The idea of eliminating electricity from docks altogether is a simple foolproof idea, but unrealistic for the Lake of the Ozarks. We need power on our docks.

Homeowners on Lake of the Ozarks need electricity for a variety of reasons, not the least of which being boat lifts, marine shore power connections, and lawn irrigation pumps, and they are the most demanding in terms of power requirements. Shore power connections for larger boats typically run 30 amps. irrigation pumps can require 3-10 amps depending on their voltage and pumping capacity, and boat lift air pumps operate in the 1-3 amp range. Along with a smattering of lights, fans, convenience outlets and the occasional small refrigerator, docks typically have anywhere from 30-50 amp services with 100 amps not being out of the question. For a typical 200 amp home service, the boat dock can often represent a significant portion of power consumption. When you consider it only takes about ten milliamps (10/1000 of an amp) to constrict your muscles and only a few dozen to stop your heart, the typical dock circuit carries enough current to kill many thousands of times over. While not all docks have electrical service, blue light requirement not withstanding, the vast majority do. If you do have electrical service on your dock, get it right, or abandon it altogether. The risk of faulty electrical service is high, and your responsibilities are clear.

Any dock installations (old or new) with electrical service are required to pass an inspection, and if you're selling your lake home you can bet the new owners will insist on one, but it won't be long before ALL docks, regardless of age will also need to be inspected and approved. If you want to keep electricity on your dock, you had better get it up to code.

How do you do get your dock up to code? The key word here is "code", and it comes from something called the National Electrical Code (its formal name is NFPA 70), written by the National Fire Protection Association, which is rather odd sounding source I know, but trust me it's been around for decades. The book is huge as one might expect and surprisingly readable, if you're into such things, but suffice to say your average handy-man is not going to be familiar with it and it is very detailed when it comes to safety requirements for electrical power and marine installation. In short, if you want to get your dock up to code, your likely going to need a professional. Of course, just about any electrician with a sign on their truck is going to tell you that they can wire your dock correctly, and many can, there's nothing special about the requirements, but you will want to have it inspected to make sure its right and in most cases an inspection is required. Oh sure, you can hire anyone you like, even do it yourself if you wish, but when the fire department comes out to inspect it and tells you it's wrong and you have to rip out hundreds of dollars of wiring and start over don't say I didn't warn you. I'm an electrical engineer, and trust me, they don't teach NFPA70 wiring specifications for docks in engineering classes. I paid to have it done just like many people do. It isn't cheap either. Depending on the services you need, the size of the dock, and a hundred other variables, your cost can be several thousands of dollars, but considering what it could cost you in lives and lawsuits, just think of it as another necessary expense. No one said living on the lake would be cheap.

Here is a PDF from Ameren that can tell you what will be expected of your installation. It is not intended to be checklist, but it will give you a very good idea of what you're in for. Also, in 2019 a small group of local electrical contractors started the "Lake Ozark Association of Electrical Contractors" in an effort distinguish those contractors committed to safety, but it is a voluntary membership trying to address the fact that Missouri has no state licensing requirements for electricians (not the smartest piece of deregulation in my opinion but I'm just an electrical engineer so what do I know) which creates some trust issues for consumers. Just remember when choosing a contractor, the only thing worse than no safety equipment is badly installed safety equipment.

Update: I've been asked about those "Life Alert" devices that you can add to a dock that detects the presence of electricity in the water. Are they effective? Are they necessary? On the issue of effectiveness, they do work, but they will drive you nuts. They are designed to detect very small amounts of voltage or current (amps) in the water and believe it or not, it happens naturally. Small electrical currents are created by a variety of natural processes. The amount of energy created is very small and harmless but your dock sensor will pick up on them and alert you. Part of the problem with any safety device is "alert fatigue". If you're constantly being bombarded by false alerts, you may not pay serious attention to one that is real. Hats off to the two engineers who came up with the idea, but it is fallible, and can easily lure you into a sense of safety that may not be justified.

Are these devices necessary? Not really. If you're dock is wired correctly, and periodically inspected (docks move and connections fail), the safety features of the circuit itself will protect you from harm. However, if you feel better having a dock alert system than by all means install one. Just be aware that if your lake home is a weekend destination, you will probably want to shut power off at your dock when you leave to avoid driving your neighbors insane with alarms going off all week while you're gone. Ask me how I know. :)

Monday, July 09, 2018

June 2018 Lake Levels and Flow Rates

Late on the post for June levels, but it's summer after all. Lake levels are where they should be and behaving predictably. Nothing notable to see and that's a good thing. Keep in mind the narrow range of data makes for an exaggerated graph scale. In reality, the difference all month long in lake levels is little more than 1 foot.