Come Thanksgiving, make a bread based stuffing, with some cranberries, celery, onions, spices, etc. Mix double what you need for Thanksgiving dinner, cook it all and save half.
The next morning, take your waffle iron out on to the porch and plug it into your extension cord or new receptacle and make Stuffing Waffles.
Your family and guests will thank you.
I used work on megawatt transmitters with 15KV DC power supplies.
Sometimes we'd hunt for intermittent arcs by taking the panels off the side of the transmitters, cheat the safety switches, turn the lights off in the transmitter room and then, under the soft glow of the 18" vacuum tubes, run the PS up to 25KV or even 30KV to get the transmitter to arc.
When newbies (of any rank) came to the station we'd hold a "safety meeting" outside the transmitter room to show them why no one (of any rank) was allowed in the transmitter room without a transmitter tech.
We'd take one of the big oil filled capacitors, use the hipot to charge it to 4 or 5 KV, then discharge it with a dead-man stick - after explaining to them why a dead-man stick was called a dead-man stick. Sometimes we'd get lucky and the metal rod would blow right out of the wooden handle. That usually convinced them to stay out of our domain.
You gotta sign in to view this old one - electrical explosion when racking a breaker in a metalclad :
I haven't looked at the ROP but I bet someone on CMP2 said look at
Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits
15a Not over 15a
The point was that is a single load. You can plug in other stuff The installer has no control over what the user might plug in so the 80% safety factor is built into 240.4(D) where the circuit is derated to
80% by the breaker required. I agree U/L has been sloppy about the plugs they allow occasionally, assuming they were valid U/L listings but for the most part anything with a 5-15 will be 1440 watts or less at 120v, no matter how it is sold. The "1800 watt" hair dryer is a good example. They pull 12a or less and I tested a lot of them when I was looking at this.
I have heard of these but never actually saw one. I noticed in New Zealand, even though they did go with 230v at 50hz, they are wired just like we would recognize, except for the color code. If you leave an inspector in a hotel room with a screwdriver, they will look ;-)
A lot depends on the grade. If you get a commercial grade 5-15 the contacts are as good as a 5-20 but if you are getting one of those 98 cent specials out of the barrel on the end cap, 15a might burn it up. U/L doesn't guarantee it won't burn up, just that the fire is contained in the device.
Well, at least the guy pulled down his face protection just before the boom. :-O
I'll bet that hurt. What do you think went wrong?
I didn't say it. Table 210.21(B)(3) did.
I was in an inspector meeting with the guy who invented an electric salt to chlorine pool generator. He said the testing process took months and they kept asking for more to blow up. Basically they make these things fail in every scenario they can think of and be sure it fails "safely". (no shock potential, no fire that escapes the enclosure) He said they never tested to see if it actually made chlorine effectively.
It said that he was racking a breaker - don't know if it was IN or OUT but I'm guessing OUT and some sort of mechanical failure shorted things in behind where the breaker stabs the bus. 14 or 28 kV is my guess. All these metalclad breakers have mechanical interlocks to prevent racking a CLOSED breaker. And usually some other interlocks as well - like on the cubicle door. Back-in-the-day we would switch in a ~ 1920's vintage indoor "switchyard" < the cubicle doors were wood > on 8 kV using a switchstick that was just a bit longer than a baseball bat. .. another row of cubicles close behind prevented use of a real switchstick ... John T.
As a kid I recall seeing a bunch of stuff wired into one extension cord in the living room of a friend and later they had a fire caused by it.
Two of my favourite Christmas movies ! :-) :
I did not see it hapen but at work we had a similar accident on a smaller scale. The electrician had the door closed and just turned on a
480 volt breaker rated for about 50 amps. Something internal arced and destroied the load contol center. That was a set of breakers that have doors about 18 inches each way. There are about 5 or 6 high and 10 feet wide,so lots of breakers. The center is fed with 480 volts 3 phase 400 amp fuses in each leg.Good thing that door was closed. No damage was done to the electrician excpt his underware :-)
The cubicals should have mechanical interlocks to prevent opening or closing a breaker with the door open. The interlocks can usually be defeated so the door can be opened or closed. That may have been his case.
On the 15KV power supplies for our transmitters we had a 3-strike breaker system. It was a combination breaker, mechanical timer and motor.
If something in the transmitter shorted, causing the PS breaker to trip, the timer would rotate 1 position (strike 1), close a contact which would power on a motor, which would drive a piston up to reset the breaker and then drive the piston back down. If there were no other shorts within 30 seconds the timer would reset to position 0.
A second short within that 30 seconds would repeat the process with the timer rotating to position 2 (strike 2); close the motor contact, close the breaker, etc. The timer would also start the 30 second count again.
No arc within 30 seconds, timer resets to position 0. If there is an arc, the timer "strikes out" by rotating to position 3 where no motor contacts are closed and the transmitter stays off.
If everything is working correctly, the switching equipment kicks in, telling the standby transmitter's power supply, which is idling at 5KV, to increase power to 15KV, switch the output from the dummy load to the tower and take over the transmission.
While all that is happening, alarms are going off all over the station and the transmitter techs are scrambling to get to the transmitter building and find out what is wrong with the other transmitter.
When those door interlocks fail < they can > there is often another mechanical interlock that trips the breaker and/or prevents the crank insertion. John T.
Overhead rural distribution power lines often have "reclosers" < circuit breakers > out on the pole-tops that will 3-shot to clear transient faults - the secondary re-close operations are specifically set so they will also blow downstream fuses - relay / fuse co-ordination it's called. Underground is a different story altogether. John T.
That is about what it looked like.
I don't recll the year,but where I worked there was a big push for the arc-flash safety. Some say it was because a company came out with a ground fault type breaker and wanted to push it as a safety standard but companies did not want to spend the money to change them out. Before those standards there was basically no unusual safety rules plant wide. Just everyone in the plant wore safety glasses and if in noisey areas ear protection.
Anyway it was some time after 1990 we had engineers to come in and lable all the big motor control centers with different ratings of arc-flash. Then we had to wear clothing and protective equipment depending on how it was rated. Minimum was all cotton cloths. For the above reason. By the way we produced polyseter from basic chemicals. Then it was gloves and a face shield, add a special over coat. From there the most was special gloves, very heavy overcoat,big helment thing over out head. There were some special rules for some circuits that about 2 supervisors had to sign off some paperwork and we had to stand on a special rubber type mat , have someone with a hook standing about 10 feet awsy with special hook to pull us off the live wires and all the other heavy duty suits.
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