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M

msdunkel

Good day,

I recently moved to Abu Dhabi from the United States. Abu Dhabi has what I imagine to be a very bad copy of the British electrical system, my home has 240v 3 pronged outlets. I have a variety of electrical equipment; some can accept 110v-240v, some can only accept 110v - 120v.

I decided to try and make things a little easier by installing 2000w 240v to 110v transformers throughout the house but I'm having some trouble. The transformer has a typical US-style 3 prong plug. When I plug that into a 3 prong British style adapter the transformer runs fine; however, the instant I plug anything into the 110v transformer output (even something as benign as a simple surge suppressor) it takes the house's main electric panel offline -- not just the individual plug' circuit, but the circuit breaker for the entire floor.

I tried to use the European style 2-prong adapter instead of the 3-prong British adapter and I'm able to run pretty much anything off the transformer now. The down side to this is I'm pretty sure I've defeated the ground in the system since anything I plug in now delivers a mild tingling when metallic parts are touched. I can even daisy chain the tingle through speaker wire, HDMI, and all kinds of other cables I never thought carried much electricity :).

This leads me to 3 questions:

1) Any idea why the 3 pronged Brit adapter causes the entire panel to shut down on me when a 2 prong European style works fine?

2) Working with the 2 prong European style adapter, am I in any real danger of electrocuting myself, or am I limited to these slightly painful electrical tinglings I've given myself over the past couple days?

3) Am I going to damage sensitive electronics (Denon receiver, Paradigm speakers, desktop computer, LCD TV, Blu-Ray DVD player) by having this rampant power running around?

I've been running my computers and monitors on this goofy setup for a couple weeks with no issues unless I inadvertently brush up against a metal part of the case. I only post now since I was very surprised to get a really strong tingle from simple speaker wire when the only connection those wires had to electricity was wall (power) -> transformer (power) -> power strip (power) -> blu-ray player (HDMI) -> amplifier (speaker cable) -> speaker. Items in parenthesis delineate the connection between components.

Thank you for your time.
 
Firstly, Yes. You have defeated the earthing (grounding) which is to put it politely, NOT GOOD. Possibly could be lethal in case of a fault.

Do you have access to any test equipment, even a simple multimeter?

I'm intrigued as to why the transformer would have a US style plug, if the primary was 240V.

It is possible that your transformer has some interconnection with earth/ground, and/or is an autotransformer rather than an isolation transformer.

As the "live" side of what you have at the moment is working, there is obviously an issue with earth leakage (ground fault current) rather than overload.

I reckon the cases of your equipment will be live at 120V AC though, so you need to find out what's going on with the transformers.

STOP USING THEM WHILE YOU'RE STILL HERE TO UN-PLUG!

By the way, how big and heavy are these "2000W" transformers?
Please post the make/model

Simon.
 
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Good day,
) it takes the house's main electric panel offline -- not just the individual plug' circuit, but the circuit breaker for the entire floor.

.

Thank you for your time.

Is this circuit breaker actually an rcd with a little (yellow?) test button with something like "30mA" amongst other things written on it?
 
Firstly, Yes. You have defeated the earthing (grounding) which is to put it politely, NOT GOOD. Possibly could be lethal in case of a fault.

Do you have access to any test equipment, even a simple multimeter?

I'm intrigued as to why the transformer would have a US style plug, if the primary was 240V.

It is possible that your transformer has some interconnection with earth/ground, and/or is an autotransformer rather than an isolation transformer.

As the "live" side of what you have at the moment is working, there is obviously an issue with earth leakage (ground fault current) rather than overload.

I reckon the cases of your equipment will be live at 120V AC though, so you need to find out what's going on with the transformers.

STOP USING THEM WHILE YOU'RE STILL HERE TO UN-PLUG!

Simon.

I think I've got a multimeter somewhere in my toolbox.

The transformer has a US style plug since it goes both ways so to speak. It can input any standard setting between 110v and 240v, and output standard setting from 110v to 240v. Since I purchased the item on amazon.com, I have to assume their primary audience is Americans who have returned to the US who want to use the equipment they purchased overseas. It can be found at this link: http://www.amazon.com/gp/product/B000MXW85A/ref=oss_product

So if I understand you correctly, you think the main problem lies in the circuitry of my transformer? I had thought that could be the case, or some gross error on the electrician's part since just about everything else in my villa is very poorly constructed.

As an aside, this country has major issues getting qualified labor, I had a fix-it man stop by the house to do some window work (leaking). He had a drill that had a power cord duct taped to another cord duct taped to another, and finally ended in 2 bare wires. He then took a screwdriver and jammed it into the ground portion of the outlet, and put the bare wires into the other two holes. Drill seemed to work and he didn't die, but it was pretty dodgy IMO. :)
 
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Ooh, one other thing I forgot to mention. When I use the British style 3 prong adapter on the transformer, the transformer does not even need to be powered on to take down the house electricity. With transformer off, I tried plugging in a simple power strip (as well as regular electronics) and the instant the plug touched the outlet the house power popped off.
 
Is this circuit breaker actually an rcd with a little (yellow?) test button with something like "30mA" amongst other things written on it?

The switch is blue, and is completely separated from the rest of the circuit breakers on the panel (it is at the bottom). In addition, all the circuit breaker switches run horizontally while this one actuates vertically. There is also a blue button right next to it that has the letter "T" on it, which I can only assume stands for test.
 
WITH THE TRANSFORMER UNPLUGGED but switched ON at it's front panel

Check input voltage tapping is set for 240V

Check Ground continuity between input plug and outlet.

Check for continuity between input and output "live" terminals, you'll know them as "hot".
If you get continuity, it's an autotransformer.
If you don't, it's an isolation transformer

Check for continuity between input (hot or neutral) and ground (on the plug pins) Continuity=bad

Check for continuity between output (hot or neutral) and ground - at the 110V socket. Continuity=bad

If nothing untoward shows up here, some live tests are required and a slight error with the multimeter could kill you.

So at this point I'd get someone in who hopefully is more electrically skilled than the guy with the drill.

Simon.
 
WITH THE TRANSFORMER UNPLUGGED but switched ON at it's front panel

Check input voltage tapping is set for 240V

Check Ground continuity between input plug and outlet.

Check for continuity between input and output "live" terminals, you'll know them as "hot".
If you get continuity, it's an autotransformer.
If you don't, it's an isolation transformer

Check for continuity between input (hot or neutral) and ground (on the plug pins) Continuity=bad

Check for continuity between output (hot or neutral) and ground - at the 110V socket. Continuity=bad

If nothing untoward shows up here, some live tests are required and a slight error with the multimeter could kill you.

So at this point I'd get someone in who hopefully is more electrically skilled than the guy with the drill.

Simon.

Simon,

Thank you for the detailed trouble shooting steps. It is getting late here and I will accomplish these tomorrow and report back. I did want to add that I've got 3 of these transformers and they all exhibit identical behavior, so I would be very surprised if it was a fault in the transformer. Possibly a design flaw, but 3/3 with the same fault would lead me to believe the guy with the drill helped assemble my transformers.

Mike
 
In the Middle East, many countries use both 380/230v and 230/127volt supplies (not sure about Dubai) the 230 volt, can in the latter instance be provided by 2 phases and an earth. So first check that your wall outlet supply is single phase 230v or 2 phase 230v You can check with your multimeter between earth and each side of the two horizontal outlets on the wall outlet. ....if you get around 120v from each, then you have a 2 phase system. Check that the transformer can accommodate a 2 phase 230v input??

The other thing with these types of transformers, there is usually a voltage input selector on the rear, It maybe a switch, or a jumper type bridge plug....make sure you select the correct voltage band.

As suggested earlier, it may be prudent to find an English speaking qualified electrician, who will/can check out your problem and advise you accordingly....
 
I must admit i think Engineer 54 is probably spot on there with 2 phase 230v systems.... Its what they use here in Barcelona, two phases at 120v each.. How would this affect the transformer?
 
Check input voltage tapping is set for 240V -- Checks good

Check Ground continuity between input plug and outlet. -- Good continuity

Check for continuity between input and output "live" terminals, you'll know them as "hot".
If you get continuity, it's an autotransformer.
If you don't, it's an isolation transformer

All good continuity, autotransformer

Check for continuity between input (hot or neutral) and ground (on the plug pins) Continuity=bad -- no continuity

Check for continuity between output (hot or neutral) and ground - at the 110V socket. Continuity=bad -- no continuity

So based on these tests, there is nothing wrong with my transformer.

I had the villa complex send out an electrician, and he immediately blamed the transformer (go figure). At least he did it in such fast accented English I could only understand a word in 3 of of what he was saying. I think he was trying to illustrate that since high voltage items such as the refrigerator and oven neither shock me, nor do they trip the circuit breakers, there can't be anything wrong with the house power. I had to concede him that point.

I also asked him about power phasing and he said the power is 1 phase 240v.

Here are a few possibilities I can think of, I'd appreciate any other suggestions.

1) My 3-prong British plug converter is bad, and neutral or hot is touching ground. I thought this could be the issue, but when I plug a native 3 prong plug into the plug converter I have no problems. It's possible that just the ground of the 110v part of the converter plug is bad.

2) There is a malfunction in the transformer that cannot be detected by the continuity tests.

3) The electrician performed a jedi mind trick on me and my house power has problems.

4) Here's another odd thing, today while trying to show the technician how my transformer works fine with the 2 prong European adapter, but you'd get shocked, nothing shocked me.

I'd really like to solve this problem so I don't die in a faraway land, AND I'd like to watch some TV while I'm at it.
 
are the circuit breakers in your distribution board single or double pole? do they switch just the Live or both live and neutral? are they about 15mm wide or all about 30mm wide? i dont trust your electrician..... if they are 15mm wide then its definitely single phase 240v..... if not then you probably have 2 phase which is not compatible with your transformer.......hope this rules something out!

dave
 
Ok, I checked the circuit board, each breaker is approximately 5/8" wide which comes to roughly 15.8mm so single phase power.

I called PowerBright, the manufacturer of my transformer and he initially blamed the house power (go figure). I laughed and told him how the electrician blamed the transformer manufacturer. Anyway, he came up with another possible cause which I think is our culprit. Apparently the UK has their Hot and Neutral leads reversed from pretty much everybody else in the world; except of course, former protectorates, possibly like the UAE. He checked with his R&D section and they seemed very confident that my problem was my US plug's hot is going into the outlet's neutral, and my plug's neutral is going into hot, which is why any load is causing the house to go apesh*t and save my butt.

I then asked about the tingling sensation I was sometimes getting from electrical equipment. He said that if I'm getting that tingling, just flip the European style connector and it would go away. When I queried about the danger of running without a ground, he did concede that should there be a major electrical malfunction, or a lightening strike, then anything connected to that transformer would be at risk, including any human that might be touching it at the unlucky time.

So, I think I have my answer, would you experts who have no dog in this fight agree with this diagnosis?

Thanks!
 
NO. you need an earth connection if you have class 1 equipment (rounded cable inc. earth connection) connected to the transformer. If not you are putting yourself at risk from electric shock.
 
Easiest way to be sure you have correct polarity on the input to your transformer, is to cut the manufactures plug off and replace with a UK styled plug top. You should know your hot and grounded wire (neutral) wire colours, as well as the ground wire colour. If your not sure , or different colours have been used, another call to PowerBright will solve this.... Then try the set-up once again...lol!!!
 
Easiest way to be sure you have correct polarity on the input to your transformer, is to cut the manufactures plug off and replace with a UK styled plug top. You should know your hot and grounded wire (neutral) wire colours, as well as the ground wire colour. If your not sure , or different colours have been used, another call to PowerBright will solve this.... Then try the set-up once again...lol!!!

I asked the powerbright representative about doing this. He said that the power cord is hard wired to specific hardware that would make this impossible. If I was to swap the wiring, it would damage interior components according to him.
 
Putting the correct type of plug on the transformer, rather than using a travel adaptor is MUCH safer!
You'll only be changing the plug, not going inside the equipment!

A multimeter is not recommended for live testing, maybe if you can pick up a NON_CONTACT voltage detector, that will be the safest way to check polarity of your supply.

Prove first at the breaker panel, then again at each socket outlet.

UK outlet, the top pin is Earth, left is Neutral and right is Line.
I'd guess at the lead on the transformer having US colours, so Green to E, White to N and Black to L.
EU colours are Green/Yellow to E, Blue to N and Brown to L.

As it's an autotransformer, the common connection must be the Neutral for safety.

A-HA!!!! It all makes sense now!

I think what's been happening is there has been a crossed polarity on the input, so the common connection has been on the Line side.
Therefore, when you have plugged in your US surge protector extension lead, the (140V?) MOVs have started to conduct, as they have 240V from line to earth. (240V surge protectors use 275V MOVs)
This current to earth is what instantly tripped your RCD.
It's also what made your equipment dangerously LIVE when you used the non-grounded adaptor to supply the transformer.

Simon.
 
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Simon,

When I flip the 2-prong European adapter over, the shocking current is completely gone, ie, I am going neutral to neutral and live to live albeit with no ground. I was surprised that the transformer manufacturer recommended I run this setup both over the phone and in writing via email. If they're not worried about me suing them for electrocuting myself, just how dangerous is this setup?

Thanks!
 
A lot of American equipment uses a functional earth in its design, so this may be what is causing your main breaker to trip, the supply could also be a 2 phase L1 L2+E using phase drop for the return when the other phase is on a rise but I doubt that as it would only really be good for an air conditioner and would cook everything else quicker than a pizza parlour...as far as I know they use single phase there and have 3 phase for industrial sites and large buildings where they are split into L1,N+E.....Floor 1.....L2,N+E.....Floor2....L3,N+E Floor 3 and so on for smaller buildings such as apartment blocks, where there would be a sub mains board on each floor feeding maybe 3 or 4 consumer units, depending on how many separate dwellings there are.....when using the 2 pin European plug, you have no earth, and also without an adapter, no fuse (I have one of those plugs here) which is a bit risky.....
When you use the transformer and it is plugged in, due to the design I am going to assume that the Neutral (ground) of the secondary windings(output side of the transformer) are all connected together and in turn connected to the earth(protective safety conductor) and that the neutral(ground) of the output socket goes straight through the transformer unit to the Neutral(ground) on the wall socket....this is because the transformer is designed for the American mains system to US standards, this would upset the circuit breaker on the supply board where you stay fooling it into an Earth Fault trip/power off.


Inside the transformer, you will probably find : the Live (Hot) wire(core) of the mains input lead goes to the Live(Hot) input (Tapping) of the Transformer, the Neutral wire(core) goes to the Neutral(return) side of the input stage of the transformer, thats the mains input side of the transformer dealt with...

Then on the output side (output/secondary windings stage) the Live output will go from the output side of the transformer to the live hole in the output socket (picture a heavy piece of wire covered in heatshrink going from the Iron and copper lump that is the actual working transformer inside the case to the back of the socket that you plug your computer/fan/tv into on the case) the Neutral (Return) on the output socket (user plug in point for your tv etc) will be a heavy wire or copper bar covered in heatshrink going straight to the back and connected to the Neutral on the supply lead for the Transformer Unit where you plug it into the wall.

on the output part of the transformer, the Neutral (return) part of the windings is probably connected to the earth as a functional earth, this is to do with the way things are done in the USA and with the acceptable levels of touch current etc being different over there, when you plug in an earthed appliance taking a reasonably heavy load, this tingle passes up the earth pin and goes through all metal cases and anything connected to earth, which includes speaker and printer cables that are designed to use the earth to get rid of radio/vehicle driving by/washing machine next door/hairdryer upstairs types of Electrical interference (Noise/Crosstalk) and that is where you get the tingle, especially more so when the item is bare metal that is partly insulated such as a PC tower on rubber feet or a metal clip next to a printer port on a plastic printer case....
When you use this transformer back home in the USA, the earth problem will go away as when you throw the switch on the back to select 110Vac (RMS) at 60Hz input or the unit auto selects (depending on how much you spent on it, cheaper units use a manual selection switch on the back) then the way the inside is configured changes, this switch will reverse the layout of the tranformer and the earth will only be used for a protective safety conductor, the neutral on the output stage giving you 220V will now be connected straight through to Neutral(ground) on your home wall via a small resistor bank inside the transformer case(to limit current) and the earth on the 220v appliance will be connected to the Utility earth all the time for safety, if there is an earth fault, your home RCD would trip, and a short circuit (broken 220v Appliance) would either blow the small fuse in the back of the transformer or the RCD in your supply board would trip, the fuse in the 220v appliance would not blow as the transformer fuse or Household mains RCD would have popped first(bearing in mind a 5 or 13 Amp UK Fuse and possibly a 6 Amp USA Fuse in the transformer and an 8 Amp RCD on the household socket ring) so resetting the RCD would just do the same thing again, trip..making it much safer for use..
The general idea behind the functional earth is usually an afterthought for designers who dont really expect their product to ever leave America and be used for step down in another country, this is just a design issue..
There are step down to USA transformers available in the UK for about 40 pounds (about 60 Dollars) which are much better designed and made specifically for purpose, getting 2 or 3 of those would be a better bet and would leave things running smoothly, and just send your other transformers back home to the US as personal effects by surface mail (by container ship-very cheap but will take about 8 weeks) as for ordering UK Transformers, you can either get them from here by Air parcel (to ship 3 units by 5 day delivery on Parcelforce Air freight would cost about 100 pounds/160 dollars) or you can order from the Dubai warehouse of RS Electronics where they keep a large stock, dont know which would be easier for you...

let me know a postal address and I will send you 12 proper UK plugs by airmail ..
 

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