There is no "knowing which phase is summed with the neutral". A GFCI uses a current transformer to sum ALL phases with the neutral. A single-phase GFCI, which is the only type most of us see, is the degenerate case of "all phases".
Perhaps the discussion at (www)(dot)sawmillcreek(dot)org/showthread.php?27322-GFCI-for-220 would clarify this, where I have not.
In any event, the NEC does not require GFCI protection on 240 volt appliances such as ranges and dryers, so apparently not enough people are getting killed by them to warrant it.
There's no reason in theory that a GFCI could not protect a range or other appliance with 3-wire 120/240 volt supply. A GFCI operates on the principle that the sum of the currents in the supply conductors (line and neutral for a single-phase 120 volt load; L1, L2, and neutral for a range or dryer) must be zero. If their sum is different from zero, then current is leaking somewhere. Any leakage current constitutes a ground fault.
True, 120-volt loads in a range or dryer such as a timer, light, or motor cause some current to flow in the neutral (grounded) supply conductor. But the vector sum of the currents in L1, L2, and neutral will be zero in the absence of a ground fault. This is true whether the supply is derived from a single-phase (120/240) or three-phase (120/208 volt) source.
After a couple false starts, I was finally contacted by someone at JENN Air who had the authority to make things happen, and from that point on Jenn Air did pretty much what any good company, concerned about customer safety and satisfaction, would do.
He and I quickly exchanged a couple e-mails clarifying what had transpired and what I personally had done about it. It was then determined that Jenn Air would like to have the burner modules in question in their labs for engineering analysis. I was sent a Prepaid FedEx return address label and I placed them in transit. Jenn Air agreed to pay me the full MSRP without depreciation for both modules.
My wife and I are now deciding if we want exact replacements or something different. Jenn Air makes a module that is not glass topped that cooks as well but has a very different appearance. We are already familiar with these, having one, which we use for canning and other long, slow cooking operations, for which the glass top module is not recommended. We most likely will add a second one and not bother with the glass tops until we know that Jenn Air has changed the design.
We sincerely apologize for the inconvenience. We see in our records you were recently contacted regarding this matter. Please feel free to reach out to us should you have still have questions or any future questions or concerns. Sincerely, Jordan
Yes, Jenn-Air was once a great appliance company. Now it is just a rebadged Whirlpool.
We bought our house NEW in 2008. One of the attractions the house had was all Jenn-Air appliances. What a complete let down! We have 3 appliances by Jenn-Air: 1) double oven, 2) stove, 3) dishwasher. All 3 have been completely removed from the cabinets so I could disassembled, diagnose, and REPLACE major parts. The dishwasher has been removed 3 times and the oven has been removed twice. The stove was removed once.
The dishwasher has had the digital control board replaced twice, the pump, and the water sensor replaced. Some other not so expensive items is the wheels on the racks have all been replaced at least 1 time. Then, of all things, the hose from the drain to the garbage disposal had to be replaced. I've never seen that go bad before. I've been in houses with 20 year old dishwashers and never had to replace the drain hose. It was super thin and flimsy. Where it went through the hole in the cabinet the plastic became brittle and cracked (too much fluoride in the water??). The cost of repairs has exceeded the cost of a new dishwasher.
The double oven has had the element replaced in the upper oven, the fire sensor replaced in the lower oven, the temp sensor replaced on both ovens, and the digital control panel.
The stove has had to have new gas valves installed on both of the front burners, and a new igniter box to send spark to the spark igniters' (never seen one of these go bad).
Bottom line, I will never buy anything associated with Whirlpool as long as I live. There's not 3 months that go by that I don't have to work on one of these 3 appliances. The most humiliating thing was the parts for the Jenn-Air dishwasher all said WHIRLPOOL on them. When I cross referenced the parts I discovered that this $800.00 Jenn-Air dishwasher was just a regular $500.00 Whirlpool that they stuck Jenn-Air badges on and raised the price $300.00.
Seriously, I'm 47 and have been living in old run down houses since I was 20. I replaced an oven one time because it actually burned out. It was probably 30 years old. I replaced a dishwasher once because I just wanted an upgrade. I've never had to replace or repair a stove. There's just nothing there to go wrong.
Had I known up front what a fraud the Jenn-Air product line is I would have negociated a lower price on the house and told the builder he can put his Jenn-Air appliances somewhere else.
Having ingested this article and comments and the one about the oven element not opening one phase of 110 on the elements by the front panel switch, my takeaways are
1. Don't trust oven manufacturers to proof their products so you can work on them with any energy applied. You should be extra careful about standing in water and changing the rack positions. Don't be reckless or assuming after a move.
2. Circuit breakers protect wiring from burning up and causing fires. They don't protect people from low-current shocks. GFI are mandated where people might be well-grounded by wet conditions near sinks and tubs and in garages. They don't necessarily apply to protect people in other conditions. Sometimes they will trip and you should figure out why as they might be telling you something is in a soft failure mode.
3. New appliances have so many bells and whistles and fancy delicate controls they cannot be expected to last. The KISS principle has been overtaken by lightweight plastic vulnerabilities. Deal with it and don't expect the companies to build back to the iron age.
[quote]But had you read my post, I commented it was an open neutral, not an open ground. Also, nowhere did I say it's a huge, rampant problem. That said, the handful of people electocuted by "hot" garage doors is apparently enough that it's part of the 2008 NEC for new construction and retrofits. So neither "spewing", nor "misinformation"....you can take up the debate with your building inspector or real estate appraiser if you don't agree with the NEC requirement. [/quote]
If you think about it, an open neutral will do nothing other than making the opener non-operational. Even if the neutral AND ground were to be open there still would be no shock hazard assuming the opener was not damaged with a fault to ground.
As for the NEC, it has become a shill for manufacturers so consider that many requirements like the expanded use of GFI receptacles and especially arcfault breakers and tamperproof receptacles a result of manufacturer lobbying not necessarily safety.
Major brands once built brand equity and loyalty through the design and manufacture of sturdy, reliable, highly functional products. And then the companies behind the brands succumbed to cheap competition or their own cost cutting measurs -- chasing shareholder value. The result is that once reputable brands have been sold to immediately 'monetize' brand equity, and the products now producd with that badge have no connection to the company or culture that made them great. Many consumers don't know that, or believe somehow it's still a great brand, and they buy junk with the old brand badge.
The company says it anticipates high-definition video for home security and other uses will be the next mature technology integrated into the IoT domain, hence the introduction of its MatrixCam devkit.
Siemens and Georgia Institute of Technology are partnering to address limitations in the current additive manufacturing design-to-production chain in an applied research project as part of the federally backed America Makes program.
Most of the new 3D printers and 3D printing technologies in this crop are breaking some boundaries, whether it's build volume-per-dollar ratios, multimaterials printing techniques, or new materials types.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.