Friday, February 3, 2012

Barn Fires

Barn Fires   
By Tom Gumbrecht     
 Originally published in Horse Directory, March 2012

There are few things in the news that affect horsemen more than reading about yet another barn fire in which multiple horses have perished.  More so than from other tragedies, I find myself physically as well as emotionally effected by these stories.  As the horses usually have absolutely no chance of escaping, I think it is probably the horse owner’s worst nightmare.

Emotions aside, in my job as a professional electrician, I am mindful that the majority of these fires are caused by faulty electrical wiring or fixtures. Over the years I have borne witness to my share of potential as well as actual hazards. Designing a barn’s electrical system to today’s codes and standards is a topic for another chapter.  For today, let’s address what we can do to make the existing horse barn safer.

I can’t cite statistics or studies, but my own experience shows the main safety issues that I am exposed to fall into three general categories:  1) Using extension cords in place of permanent wiring; 2) Exposed lamps in lighting fixtures, and 3) Overloading of branch circuits.

The first item I am addressing, extension cords, was the subject of an entire earlier article. In summarizing, I am often asked how extension cords can be UL listed and sold if they are inherently unsafe.  The answer is that cords are not unsafe when used as intended, but become so when used in place of permanent wiring. The main concern is that most general purpose outlets in barns are powered by 15 or 20 ampere circuits, using 14 or 12 gauge building wiring, respectively. Most cords, however, for reasons of economy and flexibility, are rated for 8 or 10 amperes, and are constructed of 18 or 16 gauge wiring. That’s no problem if you are using the cord as intended – say, powering a clipper which only draws 1 to 4 amperes. The problem comes when the cord is left in place, maybe tacked up on the rafters for the sake of “neatness”. You use it occasionally, but then winter comes and you plug a couple of bucket heaters into it. When the horses start drinking more water because it’s not ice cold, two buckets become four – or more. If they draw 2.5 amperes each, you are now drawing 10 amperes on your 18 gauge extension cord that is only rated to carry 8 amperes. The circuit breaker won’t trip, because it is protecting the building wiring which is rated at 20 amperes.  Next winter, you decide to remove two of the buckets and add a trough outside the stall with a 1500 watt heater, which draws 12.5 amps at 120 volts. If you thought of it, you even replaced the old 18 gauge cord with a 16 gauge one that the package called “heavy duty”.  Now the load is 17.5 amperes on a cord that is designed to handle 10 amperes. In this case it is possible to overload a “heavy duty” cord by using it at 175% of its rated capacity, and never trip a circuit breaker. What has happened is, we’ve begun to think of the extension cord as permanent wiring, rather than as a temporary convenience to extend the appliance cord over to the outlet. In doing so, we have created an unsafe condition.  Overloaded cords run hot. Heat is the product of too much current flowing over too small a wire. The material they are made of isn’t intended to stand up over time as permanent wiring must. It’s assumed that you will have the opportunity to inspect it as you unroll it before each use.

The second item on our list is exposed lamps (bulbs) in lighting fixtures.  Put simply, they don’t belong in a horse barn. A hot light bulb that gets covered in dust or cobwebs is a hazard.  A bulb that explodes due to accumulating moisture, being struck by horse or human, or simply a manufacturing defect introduces the additional risk of a hot filament falling onto a flammable fuel source such as hay or dry shavings. In the case of an unguarded fluorescent fixture, birds frequently build nests in or above these fixtures due to the heat generated by the ballast transformers within them. Ballasts do burn out, and a fuel source such as that from birds’ nesting materials will provide, with oxygen, all the necessary components for a fire that may quickly spread to dry wood framing . The relatively easy fix is to use totally enclosed, gasketed and guarded light fixtures everywhere in the barn.  They are known in the trade as vaporproof fixtures and are completely enclosed so that nothing can enter them, nothing can touch the hot lamp, and no hot parts or gases can escape in the event of failure. The incandescent versions have a cast metal wiring box, a Pyrex globe covering the lamp, and a cast metal guard over the globe.  In the case of the fluorescent fixture, the normal metal fixture pan is surrounded by a sealed fiberglass enclosure with a gasketed lexan cover over the lamps sealed with a gasket and secured in place with multiple pressure clamps.

The last item, overloaded branch circuits, is not typically a problem if the wiring was professionally installed and not subsequently tampered with.  If too much load is placed on a circuit that has been properly protected, the result will be only the inconvenience of a tripped circuit breaker.  The problem comes when some “resourceful” individual does a quick fix by installing a larger circuit breaker. The immediate problem, tripping of a circuit breaker, is solved, but the much more serious problem of wiring which is no longer protected at the level for which it was designed, is created.  Any time a wire is allowed to carry more current than it was designed to, there is nothing to stop it from heating up to a level above which is considered acceptable.

Unsafe conditions tend to creep up on us; we don’t set out to create hazardous conditions for our horses.  Some may think it silly that the electrical requirements in horse barns (which are covered by their own separate part of the National Electric Code) are in many ways more stringent than those in our homes. I believe that it makes perfect sense. The environmental conditions in a horse barn are much more severe than the normal wiring methods found in the home can handle.  Most importantly, a human can usually sense and react to the warning signals of a smoke alarm, the smell of smoke, or of burning building materials and take appropriate action to protect or evacuate the occupants. Our horses, however, depend on us for that, so we need to use extra-safe practices to keep them secure.

As I always state in closing my electrical safety discussions, I know that we all love our animals. Sometimes in the interest of expedience, we can inadvertently cause conditions that we never intended. Electrical safety is just another aspect of stable management.  I again use the words of Show Jumping Hall of Famer George Morris, now Chef D’Equipe of the US Equestrian Team, to summarize: “Love means giving something our attention, which means taking care of that which we love. We call this stable management”.

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