Good morning from the high desert, where it isn't much like winter this year. Yet, anyway. La Nina conditions generally tend to give us dry winters, and they say this is an especially strong La Nina effect this year.
The La Nina/El Nino cycle has something to do with variations in western Pacific ocean surface temperatures affecting weather patterns 6-7,000 miles east, which in turn affects how much moisture reaches us almost 1000 miles inland and one to two miles above sea level.
The impact on us here will be less snowpack in the high country and thus less flow in our river, the Pecos. We have seen this before. The river can dry up completely before the summer rains come, if they come.
Da Nang65, part of the ad hoc cadre of construction professionals and gifted amateurs who visit with us most Saturdays, and who always has something going on, sent me a little something he wrote about the origins of the Electrical Code and why we respect it, that you all might enjoy.
He thought it was more than a comment but didn't want to do a Guest Hosting. I'm sure he'll be around to answer any questions.
(from DaNang65)
A recent comment on SMHRB brought up the subject of building codes. Boatgeek made an excellent comment to the effect that the only reason something is in a building code is because somebody died.
I can't speak to the whole Uniform Building Code (UBC), but I can address the National Electric Code (NEC), it's hows and whys, with more than a little familiarity. The reasoning behind it is something every DIYer needs to know and understand if they're doing projects involving electrical work.
Many DIYers and even employees of electrical contractors think about the NEC like it's some kind of arbitrary bureaucratic rulemaking put in place for no other reason than to make their job at hand more difficult. Nothing could be farther from the truth. I'd like to take a few minutes this morning explaining some of the history, logic, and practice of what constitutes the NEC.
The first thing we need to understand about the NEC is who publishes it: The National Fire Protection Association. The NFPA was founded in 1896 to standardize the then new fire sprinkler systems. It consisted entirely of insurance companies. Most simply put, they were looking to minimize their payouts due to fires.
A year later, in 1897, the NFPA put out the first edition of the NEC, and has updated it every three years since. In 1904 the NFPA widened its membership to include the industries it sought to regulate, and, significantly, Fire Departments. The first Fire Department to join was the New York City Fire Department in 1905. The group also began to include manufacturers, contractors, unions, electrical engineers, and about every organized group with a vested interest in not burning the place down. Since it was insurance company driven, the NEC early on expanded to include not only fire hazards but electrical shocks to persons, i.e., human safety.
Where the NEC acquires the force of law is when a city, county, or other governmental body responsible for building within a jurisdiction adopts it by statute, usually in it's entirety, occasionally with the addition of special local requirements, almost never with omissions.
That's enough history, the necessary background of who, and for how long, these folks have been in their business. What's important to us is the rules; why they decide they need a rule, how they formulate it, and how it makes it's way into the Code.
We all hear about fires on the tv, quite often described as of electrical origin. When that happens some reports get made out, by the Fire Marshal, the insurance adjuster, and occasionally the insurance company's expert. A copy of every report goes to a central collection point, a data center. If an unacceptable number of electrical fires are laid to any one specific cause the NFPA decides they need to do something about it. Here the process gets interesting.
The problem is referred to a specific panel or committee, there are 19 different panels each chosen for their expertise in a particular sub-field. The panels vary in number of members, from perhaps a dozen to three times that. More importantly, they are made up of members representing the various affected groups; electrical engineers, firemen, equipment manufacturers, contractors, union members, everybody with an interest in, and some expertise at, solving the problem. Each group, of course, has a slightly different point of view, which they collectively turn toward preventing recurrences of the harm that tripped the data threshhold, which is to say, caused unacceptable insurance payouts.
Because they represent a wide spectrum of the industry their approach is geared toward practicality. Cost, ease of installation, maintenance, etc., are all considered. Having put their collective heads together they formulate a rule, sometimes it's an equipment requirement, sometimes it's a wiring method, sometimes it's an engineering practice. They're looking to prevent the problem from recurring by the most practical means.
Thus a rule gets added to the already voluminous Code. Or, more likely, a tweak to a previously existing rule. Allow me to give you a practical example.
In places where gasoline or diesel powered automobiles are serviced, all conduits entering the service area are required to be "explosion proofed" within 18" of where they enter. Gasoline and diesel vapors are "sinkers", that is heavier than air and tend to collect at or near the floor. A spark could be disastrous. Along came Liquified Natural Gas vehicles. LNG, when released, is a "floater", lighter than air, and so it tends to collect at or near the ceiling. Changing with the times, the NEC then required the same explosion proofing within 18" of the ceiling in places where LNG vehicles are serviced. It adds some cost to the construction of your neighborhood Jiffy Lube, but helps keep some unsuspecting folks from learning about the Big Bang first hand.
Most of the rules are based on common sense, if you know enough to apply common sense before the fact. Thus the requirement that wall outlets be spaced no greater than every 12' derives simply from the fact that most lamps and household appliances come with a six foot cord. Wherever you want to put that lamp, you won't need an extension cord to reach the outlet.
That same six foot rule applies to outlets near sinks, bathtubs, and other water hazzards. If it's within six feet of where it could get dropped in the water, presenting a serious electrocution hazzard, it must be Ground Fault Circuit Interupter protected.
Same with kitchen counter tops. GFCI s save lives, it's just that simple.
Another example of how the Code seeks to protect lives is the relatively recent addition of Arc Fault Circuit Interrupters for outlet circuits which feed rooms where people sleep. The biggest cause of electrical fires isn't short circuits, a short will pretty usually blow the breaker or fuse immediately. But arcing connections, most often an ill made splice, will generate sparks and heat without ever drawing enough current to trip the breaker. Sparks and heat near combustible materials and, well you know how that turns out. The NEC requires that rooms where people sleep be protected from that situation.
Every rule has that common sense basis. The requirement that electrical lines be strapped within specific distances of a box, for example, varying with the type of cable or conduit, is based on the idea that any mechanical stress on the conductors be relieved before it gets to tug on the splice, setting up that arcing that causes fires.
The DIYer generally need not concern themselves with vast sections of the NEC that deal with special locations or conditions. The DIYer generally needs only practice the few simple rules that can be found in the how to books available at most supply stores. For code compliance and fire safety, strict attention must be paid that the circuit breaker or fuse is always the weakest link in the chain, by design. Thus, for example, if the house is wired with # 14AWG wire, which is rated at 15 amps, and the 15 amp breaker keeps tripping, replacing the breaker with a 20 amp breaker is not an acceptable solution. A continuous load of 18 or 19 amps will not trip the breaker, but may well heat up the cable within the walls sufficiently to ignite combustion.
My first day of electrician school, when JFK was President, the man told us plainly "Rule Number One: Do Not Burn the (expletive deleted) Place Down."
Thanks, DaNang65. That was informative.
I will also point you all at SMHRB #1, in which I discuss electricity in the home and a few things you ought to know about it.