Here’s a sure red flag the home contractor you’re considering is untrustworthy | Lrd12 Overload Relay

Over and over again, I have heard HVACR technicians and electricians quote rules of thumb regarding wiring sizing, and I have witnessed and participated in many heated debates on the topic.

One of the best demonstrations I’ve ever seen, was at the Dayton hamvention. DP&L (Dayton Power & Light) set up several short poles with standard 7200 to 220 center tap transformers. By back feeding the secondaries with 220 from the breaker box, they could energize the 7200 lines and began demonstration what happens when you encounter these wires with numerous items. Antenna masts, kite strings, and even a hot dog were used to show the immense power available, and the audience was always suitably impressed.

That wouldn’t make things any safer, per se. It would give you an additional diagnostic datapoint as to which of the two 120V inputs has the reversal. But the primary symptom of a hot-neutral reversal is the angry buzz from the third relay combined with the third light not coming on.

You likely encountered a shared neutral between more than one circuit. You have to switch off the breakers for all the circuits that share the neutral.

There are lots of AC coils out there – in my parts bins I have AC driven relays, and AC solenoid valves. How do they work?

The QD terminals are totally fine as long as you have a ratchet crimper, which I saw you said that you did.

Operating temperatures are another consideration. Assume the ambient operating temperature for this application ranged from 0 to +70°C. This would be within the MOV’s -40 to +85°C rating, and there would be no requirement for derating of surge current or energy across this temperature range.Taking high-line tolerance into account, a 275-V ac-rated MOV may be chosen for this example. Using a 2-hp, single-phase, medium-sized motor, the MOV’s required surge-current rating would be determined by the peak current induced at the motor supply. Assuming a service location for the motor and a line impedance of 2 Ω, it was determined that a 3-kA lightning surge was possible. In this case, one datasheet indicates a maximum clamping voltage of 3 kA at 900 V, which is below the 918-V suggested stator-winding withstand capability. If the motor’s operational life were estimated to be 20 years and specified as being able to withstand 80 lightning transients during term of service, the datasheet pulse-rating curves would verify a rating of 100+ surges.

Westinghouse（西屋）： OVATION系统、WDPF系统、MAX1000系统备件Invensys Foxboro（福克斯波罗）：I/A Series系统，FBM（现场输入/输出模块）顺序控制、梯形逻辑控制、事故追忆处理、数模转换、输入/输出信号处理、数据通信及处理等。

Waterjet, who seemingly has no concept of how a basic opto-isolated diac-driven triac circuit works, chimes in with useless blabber about insufficient current ratings of the *optoisolator* — seriously? If you’re going to throw stones at someone, perhaps you could verify that you have somewhat of a clue of what you’re talking about?

While if we take the same supply and drive it with 300 volts DC, then it will only need a bit less then 4 amps. And this is in fact going to put our rectifier under less load then when we run it with 110 volts AC.

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While I found enough to quibble about to justify my role as a reviewer, I also found the Sony A55 and A33 to be uniquely compelling cameras. The most telling point was how hard I found it going back to an "ordinary" SLR after just a day of shooting with the A55. I’ve long been an avowed EVF-hater, but the viewfinder display on the Sony A55 is good enough that I found myself sorely missing it when I returned to shooting with a conventional sub-frame SLR with a typically small optical viewfinder. The Sony A55′s shooting speed matches that of professional models costing literally thousands of dollars more thanks to the unique pellicle mirror design, and its uniquely Sony features (Handheld Twilight/Multi-Frame NR and Sweep Panorama modes in particular) take the A55 places no other SLR has gone before. I was also pleasantly surprised by how comfortable the Sony A55′s grip was, given the tiny body size. I still prefer having more to wrap my fingers around, but this is as good a grip as I’ve seen on an SLR body this compact to date. While its primary target clearly is not the entry-level shooter, the Sony A55′s Auto+ mode takes it closer to true "just push the button" simplicity in auto mode than any other camera we’re aware of, enabling novice-level users to enjoy the multi-shot and other Scene modes without having to worry about which to use when. At the other end of the spectrum, for the enthusiast with time to become acquainted its capabilities and familiar with its quirks, the Sony A55 expands the realm of amateur photography further than any SLR to date. In the A55 and A33, Sony has used outside-the-box thinking to deliver a uniquely capable, functional, and well-designed SLR. Hot on the heels of their category-redefining NEX-3 and NEX-5, Sony’s engineers have now likewise redefined what consumers can expect from an SLR.