220V line to line vs 220V line to neutral

[jaberje]

My country government decided to standardize the voltage rating to 400/230V for residential and commercial buildings and allowed a few years to implement this action. In some areas of my country we currently use 220/127V. As an interim solution before full compliance, we are proposing to eliminate the 127V L-N and use 220V L-L, with DP GFCI at the Panel, BS Type Outlet with DP switch, appliances with BS type fusible Plug, and warning sign on the outlet stating to disconnect before servicing. Some engineers opposed this proposal stating that it is not safe to use in residential units. some of their arguments are: Some domestic appliances (designed in Europe) are designed based on 220V L-N where the Neutral might be grounded, or the Neutral might be connected to the body of an appliance, so in case this appliance is connected to 220V L-L, the Neutral will be energized and create a safety hazard. Our answers to these engineers were: There are no standards that call for grounding the Neutral or connecting the Neutral to the body of an appliance, and if such an appliance exists, this is a bad design and no one should purchase and use such an appliance.

I would like hear professional opinion and/or concerns associated with our proposal. Thank you.

 

[Skogsgurra]

I am very strongly against introducing a hasard like that.

If it weren't a new situation. And if every citizen knew about the system and its risks. And if you vacuumed the country to remove every old radio set, TV set, hoover, fridge, iron, mixer, fan, power drill etcetera etcetera. Then I would not object.

But, as I understand it, there is probably a mix of antique, older and newer devices in use. Devices where the chassis may be connected to N. That is the rule, by the way in many European countries with TN-C systems where no distinction is made between N and PE.

If such a device is connected to a L-L outlet, there's a great risk that someone will be killed or a fire started. If you can guarantee that it will not happen, then go ahead. But, can you? Think about it for a while. You cannot, I think. So, don't allow it.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[waross]

You would be using your GFIs as a first line protection rather than a back up for life safety. Just because it is invisible doesn't mean that it is not a hazard. Most accidents are a combination of two or more things going wrong simultaneously. This arrangement is the "First thing gone wrong".
Mini spare tires are common on many automobiles now. Typically rated for maximum 80 KpH and a range of not to exceed 100 Kilometers.
This may be similar to putting on the mini spare and heading off with a car fully loaded with family and luggage on an extended trip at autobahn speeds. It will work until it fails and someone dies.
I'm with Gunnar.

Bill
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"Why not the best?"
Jimmy Carter

 

[VEBill]

Assuming that you can't arbitrarily increase the voltage of the medium voltage distribution system... Therefore, for each neighborhood, the implementation of transition would be a crew showing up to remove the pole-mounted transformer and install the new one. Other crews should be going (or have gone) from house to house to do whatever needs to be done to ensure a safe power-up at the new voltage. This may include confiscating (and I hope replacing*) appliances and educating the consumers. Those crews should be in the area at power-up, and they should bring fire extinguishers. This sort of neighborhood-by-neighborhood approach seems natural and reasonably safe. I don't see how you'd need or want any interim steps. I agree with the others that you should not experiment with new wiring schemes. Simply move each batch of houses from one standard to the next, using a one-at-a-time transformer replacement process, with careful on-site supervision.

Are the outlets changing? What about wired-in fixtures (e.g. florescent light ballasts, door-bell transformers, heaters)?

(* Many years ago, the Canadian province of Ontario converted from 25Hz to 60Hz. Reportedly the bottom of Lake Ontario has a layer of appliances that were replaced with new ones at the power company's expense. The old ones were sunk to eliminate fraud.)

Disclaimer: Not my field.

 

[waross]

Many integral HP motors were inspected and many were re-wound for 60 Hz. I worked for a time in a plant where we re-commissioned a section that had been unused for years. Most of the motors had tags dating back to the great change-over indicating that they were now suitable for 60 Hz operation.
I also, when I was young, I worked for an old repair man who would remember working on the great change-over in Ontario.
For many years some 25 Hz generation remained for one or more industrial plants. I understand that some 25 Hz was produced commercially into the last decade and may be still in operation.
Disclaimer, No, I'm not that old. My information is either based on reading papers or long ago conversations with people who where there.
Good suggestion VE1BLL, in your information agrees with anything I have heard about the change-over.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[cranky108]

Just a thought, but the problem with countries making there own standards is that to maintain that standard requires a standards board, testing agencies, and a sizeable market that will attract manufacturers. Given it was once a much smaller task, and many countries already have standards to maintain, it is possible to follow another countries standards to attract a larger group of manufactures.

A small market for any product translates to higher consumer price for goods. And it makes a number of less safe alternitives attractive. Example: In one country I saw an extention cord made from a pair of 22 guage wires for each leg (I assume 22 guage because the wire looked like what we call phone wire). This would not happen as much if inexpencive cords were sold in stores.

This is a simular thing like we have here. The NESC is owned by a group which makes money selling copies of the code to people. Cities, counties, and states adopt the standard and need little technical knoledge to have a very intensive set of safety standards.

Just my 2 cents.

 

[living2learn]

if the load is protected by a GFCI (differential) and the appliance is connected with the old neutral bonded (now L-L) to the enclosure and it was not properly grounded (EGC). The enclousure would become energized and if someone touched while properly grounded than a shock/incident would occur (as described above).
Depending on the GFCI response and settings, could someone still get injured?

 

[waross]

There would also be issues with the grounding conductor sharing the neutral current and tripping the GFI (RCD)

Bill
--------------------
"Why not the best?"
Jimmy Carter