“I was working in the lab late one night when..” snap crackle pop the lights went out.
Actually I was in my basement wood working shop trying to put together an impromptu kids toy. The toy was a contraption made of small pieces of wood, bobby pins and elastic bands. Something slipped, the elastic snapped and small parts went flying. Snap – crackle – click – no lights. (The pop came later.)
Oh! oh? Burnt ozone smell. Quick – flashlight – electrical panel. Tripped circuit breaker – that won’t reset.
Eventually I found it. A bobby pin fused across the positive and neutral prongs (also called blades) of the chest freezer plug that was partially out from the wall plug receptacle.
So what happened?
Well.. the snap was the elastic band that propelled the bobby pin across the room, which hit the wall, fell down across the plug blades.
The crackle was the electric arcing which fused the bobby pin to the plug blades. The arcing produced the burnt ozone smell, scorched the wall receptacle plate and slightly melted one side of the plug.
The click was the circuit breaker, working as it is designed to do, tripping to the off position and breaking the circuit. This prevents fires, electrical shocks and limits damage to equipment.
The metal pin caused an electrical short across the plug blades, so the circuit breaker reacted and turned off the power to that plug and coincidentally the basement lights.
This all occured inless than a second.!
The pop came later (after replacing the freezer plug) when I put the circuit back on and an incandescent light bulb said goodbye.
This all happened years ago. I later got an electrician in, to replace the receptacle and separate the lighting from the plug circuits.
I asked him if the receptacle orientation was wrong and wouldn’t it be better if it was positioned so the third blade (grounding prong) was upper most.
He said no, there was no rule or trade practice preference and there is no mention of it in any electrical building codes. There is also no unanimous agreement amongst electricians on the subject so it is left to user or installers’ preference.
In all my experience I have asked the same question of many electricians, electrical engineers and architects. I have gotten essentially the same answer with minor variations. Until now!
Yes! I found it in the March 2008 issue of Taunton Press’ ‘Fine Homebuilding’ magazine. It is on pages 100 to 102 in the Question + Answer section. This is a very succinct practical answer from a master electrician in Rocky Mount, Virginia; Rex Cauldwell.
His answer says that although there is no official right or wrong way, logic and electrical common sense dictate that:
1. Wall outlets that will be used by appliances with immediate turn plugs (clothes washers, refrigerators, freezers and window air conditioners) should be oriented so that the plug inserts without having its’ own cord loop over itself, as the downward pull of the cord will tend to ease the plug out of the receptacle.
2. Otherwise the grounding slot should be on top. Then for a partially pulled (or partially inserted ) plug, something metal falling on it ( knife , pin, nail ,screw, coin, coat hanger etc. ) won’t cause a direct short as the grounding pin will deflect the item from the terminals.
3. And for receptacles installed horizontally the grounding slot should be on the left, which places the wider neutral slot on top. That way anything metallic hitting exposed blades will hit the grounded neutral blade instead of the hot (powered) blade.
Nice to have a good answer.
The practical SAFETY lessons are:
1. Check that plugs are either all the way in or all the way out.
2. When remodeling, renovating or your cousin the electrician is visiting, verify that the receptacles are installed according to the above rules.
Fuses and circuit breakers are major players in a SAFETY SYSTEM that is wired into your home circuitry.
They are installed by professionals who insure that the quantity and size (amperage) used will provide the load capacity to do what is desired while providing the highest degree of safety.
This is why the use of oversize fuses, reliance on extension cords and the bad habits of penny coin or tin foil ‘bridges’ in fuse boxes is so dangerous. These practices circumvent or short-circuit the safety systems. Quite shocking! Literally!
Circuit breaker panels are more modern and are more idiot proof than fuse panels. Tripped breakers can be reset, so the absence of the required fuse or fuse size doesn’t result in “long term temporary solutions”.
Circuit breakers should be tested periodically by manually tripping the breakers to ensure that none have seized or weakened. You want to know they’ll work on demand, in an instant.
The snap crackle pop incident recounted above occurred in a fraction of a second.
The safety system worked. It was all in place.
It did take hours though to find, understand, make repairs and restore the lighting.
Don’t know if I ever did figure out that kids toy.
Original blog post on ActiveRain: Link to Blog Post