Ask Me Help Desk - Electrical Spike--What Caused It?

Hi,
An electrical spike zapped our transformers and I'm trying to figure out what caused it. I'm not an electrician by a long shot, so I'll put in all of the information that I know about, and hope that one of you electrical whizzes can help.

Background:
1. I live in Israel, which has 240 voltage, DC, in the walls.
2. Our electricity is 3 phase (I don't know what that means, but it's what an electrician said.)
3. When we moved into our new apartment, our refrigerator began to short occasionally, and when it did, the main fuse shut off. After a 12-24 hour wait, the refrigerator works again. An electrician suspects moisture between two wires, but he hasn't been able to find the problem.
4. Recently, we had an air conditioner using an inverter installed.

The problem:
1. The air conditioner was running. The main fuse shut off. This time, even after unplugging the refrigerator I couldn't turn the main fuse on.
2. I called an electrician. He tested the inverter and said that it was shorting and was the cause of the problem.
3. He also said that the wiring of the air conditioning unit had been installed incorrectly. It should either have an on/off switch or be attached to a wall outlet, but it was attached directly to wires in the wall.
4. He also said that the blue neutral wires in the fuse box had an electrical current in them, which he fixed.
5. Although the electrician said verbally that he thought the air conditioner had caused the problem, when I asked him to put that it writing, he didn't want to.
6. Following this episode, our laptop transformer cords and a cell phone charger stopped working, so we had to replace them.

The air conditioner installers came to the house and disowned all responsibility for the short.
1. They claimed that it was impossible for there to be an electrical spike throughout the house caused by an appliance.
2. They looked at the incorrect installation of the air conditioner wires in the wall and said that it didn't look burned, so there was no problem there. (They attached the wires to a cord that plugs into an outlet.)
3. They looked at the inverter and said that there was no damage there, stating that it didn't look burned.
4. However, after I insisted that they test it, they said that the inverter was causing a short, and called the company that has it under warranty to send a repairman to fix it.

My main question is whether I can reasonably lay the blame on this outage (and my burned out transformers) on the air conditioner installers.

Thank you for your help!

I think you need a different Electrician.
I never heard of 240 Volts DC, Three Phase. Doesn't mean their isn't any?

The Neutral should have current.
The AC can short, but would throw a breaker.

You need someone with a little more experience. Good Luck.

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1. I live in Israel, which has 240 voltage, DC, in the walls

.Is that really correct? Power grid for Israel is shown as 240V, AC. DC power cannot be transmitted over long distances. Are you in some special circumstance?

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2. Our electricity is 3 phase

I doubt that also. How many wires are in the cable that brings power into the house? Plus there is no phase to DC power, so the two statements are in contradiction.

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2. I called an electrician. He tested the inverter and said that it was shorting and was the cause of the problem.

An inverter is used to convert DC power to AC power. Could you mean transformer? A transformer is used to change the voltage of electrical current. What is the voltage rating of the air conditioner? A defective transformer could cause a short circuit, therefore tripping a breaker.

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3. He also said that the wiring of the air conditioning unit had been installed incorrectly. It should either have an on/off switch or be attached to a wall outlet

That is a safety requirement for servicing the air conditioner. Would have not effect on its operation.

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6. Following this episode, our laptop transformer cords and a cell phone charger stopped working, so we had to replace them.

Suggest you use surge suppression power strips for all electronic devices.

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1. They claimed that it was impossible for there to be an electrical spike throughout the house caused by an appliance.

Agree.

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4. However, after I insisted that they test it, they said that the inverter was causing a short, and called the company that has it under warranty to send a repairman to fix it.

Again, I assume you mean transformer.

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My main question is whether I can reasonably lay the blame on this outage (and my burned out transformers) on the air conditioner installers.

I don't see how. Even if the device (inverter/transformer) was defective it wouldn't be the installers fault.

Voltage spikes (power surges) do occur, but they come down the line.
A voltage spike could have occurred, damaging transformer, not transformer causing power surge.
Lightening hits a line, you get a power surge, car hits a pole, a 50,000 volt line comes down on a 7000 volt line, you get a power surge, other stuff happens, you get a power surge.