Home user, very concerned over middle east wiring safety

[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...

 

[Golden_Boy]

Absolutly correct. Cheap autotransformers are no substitute for the real thing. Splash out on a few 1KVA Isolation transformers, jobs a good un.

 

[msdunkel]

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...

1st, thanks to you and all the others who have replied. My brain hurts from following this thread but that's probably a good thing.

As to what I should've bought, perhaps... But I'm just a guy with some electronics he wants to protect not an electrician or engineer. How would I have known that these problems would ensue? I had these types of transformers when I lived in Germany and never had a problem (was it grounded there on the 2 prong European system?).

So based on this info, is there any relatively simple way to make my current transformer work, or do I have to purchase different ones?

 

[WDMDL]

If your surge protection strips are causing the GFI (RCD) to trip, there must still be a polarity issue which is resulting in there being more than 140V AC between hot and ground, or neutral and ground.

Remember what happened when you turned the plug the other way up with the non-grounded adaptor? the shock hazard was gone.
This is because the common connection of the transformer was then connected to neutral.

Well basically you need to create the same situation, BUT with the ground properly connected.

Think about it:
The autotransformer is a single winding of wire round an iron core.
Let's say for instance you have one turn for every volt.
we'll call the start "zero"
We put on 110 turns, make a connection out and then call that the 110 tapping.
We put on another 110 turns, make another connection out and then call that the 220 tapping.
We put on another 20 turns, that's the 240 tapping. 240 turns altogether.

Now if we put 240V between the zero and the 240 tapping, we will get 110V between the zero and 110 tapping, whichever way round the 240V went in.

BUT

The supply in your house is configured such that the neutral and ground are connected together at the transformer (Pole, substation, etc)
So, there is 240V between hot and neutral, and also hot and ground.
(You may measure a small voltage between neutral and ground, but can be ignored for this purpose)

Now, you connect your autotransformer.
Let's assume the connections within the transformer case, including the front panel outlets are the correct polarity.
If it is connected correctly, with the "zero" connected to the neutral, you will have 110V between hot and neutral, 110V between hot and ground and zero volts between neutral and ground. Surge protection MOVs are not conducting.

If there is incorrect input polarity, with the "zero" connected to hot / line, you will STILL have 110V between output hot and output neutral, BUT you will have 130V between output hot and ground, and 240V between output neutral and ground. Surge protection MOVs between neutral and ground will be conducting, and depending on exact type, the MOV between line and ground may start to conduct too.

If you've put the UK plug on and still got the same problem, cross the line (hot) and neutral in the plug and try again.

If this cures the problem, you need to have the polarity of your socket outlets checked. You can do this with one of those plug-in testers I mentioned, or if the apartment is rented, get the owners to sort it out.

Having one of those socket testers is a good idea, especially if you're likely to want to plug your transformers in anywhere else.

Simon.

 

[Engineer54]

msdunkel wrote....
''I had these types of transformers when I lived in Germany and never had a problem (was it grounded there on the 2 prong European system?).''

The DIN plugs you talk of here ''are'' grounded, the earth is via 2 scraping earth contacts either side of the plug.
These German outlets and plugs are however not polarised, you can insert into the wall outlet either way!!!

Were the transformers of the same make and model type?? The transformers you have just purchased are manufactured in China, using Japanese transformers. It would have been good to see a photo or two of the opened (lid off) transformer, so that we could see the connections and the components used in it's manufacture.

Simon has given you a few pointers here, and will be well worth investigating. But if you can take the lid off one of those transformers, it would give us a much better understanding of the unit and could probably lead to a conclusion for you.... So, any chance of posting a couple of snaps or so here, for us to look at ???

 

[msdunkel]

Going to bed now, but taking off the lid is no problem, just a few screws. I'll get after it tomorrow if I haven't solved my problem by then. thanks!

 

[msdunkel]

Ok, did a few more tests and I think I found the problem.

I tried checking continuity between the output hot and output neutral leads, and got continuity -- not a lot, but it's there. I've got to assume that when I plug in an appliance there is enough resistance in the appliance to keep the GFI from tripping but when I plug in a surge suppressor, there is pretty much no resistance.

Would you agree this is most likely the cause of my house GFI tripping every time I try to plug a power strip into my transformer?

 

[msdunkel]

I am composing an email to the manufacturer and wanted to make sure I had this one fact correct before I hit send.

With the transformer unplugged, and the on/off switch in either position I am getting continuity between neutral and hot. Can you please confirm that this is indeed a bad thing?