Home user, very concerned over middle east wiring safety

[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.

 

[Engineer54]

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!!!

 

[msdunkel]

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.

 

[WDMDL]

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.

 

[msdunkel]

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!

 

[grantr37]

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 ..

 

[telectrix]

a very technical thread, this. and here was i, thinking that middle eastern wiring was concerned only with connecting detonators in a semtex waistcoat.

 

[grantr37]

just to add, with American plugs , as you know, there are a few different designs, some with straight side by side pins, and some with slightly inturned pins, the older sockets/plugs used in older buildings
(the straight ones) allow for accidental polarity switching ie Live(Phase/Line) and Neutral (Negative/Return) being swapped by turning the plug upside down and shoving into the wall, whereas the new ones dont fit in reverse, the European plugs have the same problem.
when dealing with a step down only transformer or a lamp or something, swaping the L and N connections will not make any difference to opeation..a drill or washing machine is another matter though...

your LCD TV and PC should have a Dual power supply inside anyway as they will have been designed for the world market, so you may be better off just checking if that is the case, and if so you can get a UK IEC lead for each of them and plug them in to the wall outlet.
could you put a photograph of the white/silver labels on the back here please and I will look at them and let you know, or you could let me know the manufacturer and model numbers....


have a good day

 

[malcolmsanford]

Right as someone out here .......................I can only say really that it is no good applying logic to electrical systems ...there isn't any. There will be no earth at the socket, suprised if it's wired in the correct polarity, the MCB will be some GE rubbish that was rejected in America and shipped out, I would not go anywhere near it with a multi meter let alone tools.

Go down the local electrical souk and get someone that looks fairly inteligent and take him home with you and he will sort it out for less than 20 pounds or in silly money $35

 

[WDMDL]

How safe is your setup?
Well with correct polarity and correct earthing, it's perfectly safe.

Once the polarity of your fixed wiring is proved correct, use of the proper BS1363 plug on the transformer will ensure you have no further problems.

One of the 3-neon test plugs for socket outlets (Martindale, Socket & See etc) would be a good thing to have, as you could check any socket you wished to use.
While they don't test for Neutral/Earth reversals, the RCD would be tripping every time you plugged ANYTHING in if they were reversed.

Simon.

 

[Engineer54]

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.

What Simon has advised here is exactly what is happening with the use of these transformers and the extension leads your using. So as i advised before swap that American supply plug top for the British style plug top, making sure the transformer supply cable cores are correctly connected in the new plug top. All you are doing by this operation is correcting the polarity entering the transformer, and therefore the polarity on the secondary side of the transformer.... I'm confident that your problem will then be ''no-more''

 

[msdunkel]

Ok, I went and got a proper British style 3 prong plug installed on my transformer with proper wire leads and the same thing is still happening; however, I have a bit more information.

Situation 1: Plug in transformer and turn it on: WORKS FINE
Situation 2: Plug in transformer and turn it on, then plug any electrical device in: WORKS FINE
Situation 3: Plug in transformer, plug in any POWER STRIP/SURGE SUPPRESSOR (I tried 3): GFI TRIPS
Situation 4: Plug in transformer, plug in APS H-15 Power Conditioner (very high quality item, but at heart it's just a really good power strip/surge suppressor): GFI TRIPS
Situation 5: Plug in transformer, plug in 2-prong extension cord with multiple outlets: WORKS FINE

The key to this is when I plug in any 3-prong power strip/surge suppressor into the 110v transformer output; whether the transformer is on or off, whether the power strip is in the on or off position, the GFI to the house trips. I would also like to add that the upstairs and downstairs to my home are on different GFI panels, and this happens to both levels, any outlet I try. The entire goal here is to let me use 3 2000 watt transformers in the villa, then put a quality power conditioner in line so I can avoid equipment damage from crappy middle east power.

Any ideas why my house doesn't like the power strips?

 

[Engineer54]

Are these US style extension leads also?? Then you may need to change the polarity on those also, seems your still getting N-E leakage to trip the GFI. Anyone else in your apartment block having the same problems ?? If not, ask them what they are using. ....Mixing US and UK electrical stuff is likely to cause some problems, that you will need to address like the polarity of the plug tops etc....

 

[msdunkel]

Yes, they are American power strips, but why would a basically inert power strip trip the GFI when I can plug in a 700 watt dehumidifier and it doesn't?

 

[Engineer54]

It's the suppression circuit on the strips thats probably causing the gfi to trip... MOV's still conducting. Your power conditioner will also likely to have a similar arrangment on it's imput...

 

[Engineer54]

One reason why you should have purchased ''double wound'' transformers instead of ''auto transformers''!! There is no direct connection between primary and secondary windings on the former, while there is on the latter... The GFI's would not then have seen a problem with the suppression MOVs on the leads or on the power conditioner.

The former would of also added a good deal of protection in eliminating noise on the line... while the auto transformer offers none...