One Phase Appliance

Hi

the current path single phase will see it as a load .so generally it will not effect it anyway but you must consult the appliance user manual for this kind of stuff . i think the system is TN - C in your country in which the neutral and earth combines together .

Ikhanuk:

What do you mean by "as a load". I dont think it is safe enough. I measure the voltage between the hot wire from the socket and the floor where I am standing on. The meter shows about 60V.

When the polarity changes, I am sure for 100% that the appliance casing would become live. Yes, it is dangerous because what is happening with the equipment is that there is a leakage.

Took another measure between the frame and the water spout, I got 18V but why the RCD did not trip when my hands touching the casing? You see that the hot wire is connected to neutral, and neutral is connected to the casing.

The manufacturer, I guess it is a local one in China. I will find sometimes to ask several famous ones like LG, Toshiba...

It is wrong shematics in which netral wire is connected to earth. For domestic el appliencies I have seen till now it is fully indifferent which pole of them receives neutral "polarity," which the live.

If the refrigerator stays away from any metall pipes, ducts, etc, if the floor is dry and not-conductive, then you may live happily without earthing it.

Once my family had a refrigerator which had a potential on its case, not high to shock, but still some. I was a kid, and when I become a grown up and electrician, I earthed the refrigerator. Soon it burned, however it had worked fine for more than 10 years.

The compressor's motor winding had probably been shorted to the motor wall from the beginning - low quality refrigerator it was, what did not impair its work, but what led to its very quick death after my "earthing".

Yuri B:

How to you know it gots a potential on its case? By measuring or checking by electrical testing pen? How much was that?

Here in my house, every casing got potential on every casing and I am sure about that. My Mom got shocked when she was working with the electrical cooker.

It is not safe at all especially for children.

With an analogous voltmeter - one with the scale and moving pointer, measure the potential on the cases of all the appliances, against the metall pipes, ducts, metall parts of the construction, other metal case appliances, anything current conductive that might stand nearby. Reverse poles of the plugs - measure againg. Make measurements at different times - when the machines are idle and when they are working. There should be no voltages shown - the pointer should stay still.

If some voltage is shown, either shematics is wrong (and earthing does not perform its function or there is no earting), or the appliance's insulation is faulty (and it is not earthed). Either repair it - look for the reason the potential appears on its case - or install it in such a way as to preclude any possibility of simultaneous touching it and the current leading parts close to it in the room.

So, in brief, take cares.

Hi,

In the US, appliances like this will have 3 wire plug. The neutral will never be connected to the frame. Even modern 2 wire plugs will only plug in 1 direction (one pin is wider than the other). What you describe is very dangerous. You know how to make it safe. Don't hesitate! I suggest you consult a book on electrical code for your location.

-S

For your safety, you have to re-wire the system by your self or, preferably with a knowledgeable electrician.

Ensure a three-pin plug that includes an earth pin. Phase and neutral lead to required point separately all along and the earth wire is connected to the body of motor/compressor and the body of refrigerator.

This way there is no way the polarity would reverse and any electrical leakage is duly earthed. Safe for you and your family.

It is typical in Asia to have 220 volt appliances and they do come equipped with just a 2-prong power plug. Power lines are labeled as L1 and L2, and both are considered "Hot" - meaning that if you measure each line, using the earth /ground as the reference, you will get a reading of 110 Volts per line! The "Neutral" white wire nor the "Grounding" green wires are not commonly used in that part of the world?

Not like in the U.S. where standards exist, it is very seldom that any color codings for the wire are used in Asia. Where safety concerns are considered secondary and behind to what many considered as more important economics of things!

Some 220vac appliances have "double insulation" - meaning they don't use an earth pin.

This comment will come out with the other question? Here in VN, double insulation equipments (actually most of electrical appliances) are produced with 2-pin plugs.

If you said "class II", so all of class II equipments in the US, UK and Australia/New Zealand are made with 2-pin plugs also? I wouldn't think so.