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Posted By: mvp1 Ground wire in Brazil - 04/29/02 09:02 PM
I used to live in the US and I got used to the three prong connectors with a ground pin. Now, here in Brazil I only see two poles... No ground. The electritians explain to me that the ground is connected with one of the wires. To make things worse they have electric showers with the two poles... How dangerous this can be?
Posted By: pauluk Re: Ground wire in Brazil - 04/29/02 09:25 PM
Hello & Welcome!

Yes, one of the two wires (the neutral) from the outlet is normally connected to ground back at the main distribution panel and/or at the power company's transformer in the street (different methods are used in different countries).

The third hole on a grounding type outlet also connects to ground, but under normally conditions it does not carry any current. It is there purely as a safety feature to protect you in the event of a fault.

Even though the neutral (white wire in the U.S.; not sure what color it would be in Brazil) is connected to ground, it DOES carry current in normal use, and cannot also be used as a protective conductor. If you tried to ground the frame of some portable appliance to the neutral, and that neutral wire became broken somewhere, then you could have a very dangerous situation where the frame of the device becomes live.

Not sure what supply voltage you would have in your area. My data lists Brazil as being 127 volts in some areas and 220 in others.
Posted By: mvp1 Re: Ground wire in Brazil - 04/30/02 12:09 AM
Thanks Pauluk. What I have here is an electric shower (127 volts). Metal case. What I see is that the water passes through a resistence and warms up. There is a ground screw that is connected with a wire to one of the two poles (both are black...). I am scared...
Posted By: pauluk Re: Ground wire in Brazil - 04/30/02 05:46 PM
From your description, I think you have good reason to be scared.

It does sound as though someone has just tried to ground the metal case of the shower to the neutral. This is VERY dangerous, because if the neutral wire ever became broken somewhere along its length, one of two things would happen:

1. If the shower is connected with metallic water pipes and these are properly bonded to ground, then the current that normally flows in the neutral conductor will flow along the pipes instead.

2. If the shower is coupled to the water supply with plastic pipes, or with metal pipes which are not properly grounded, then the whole metal casing of the shower would become live. In fact, if metal pipes are used but are not grounded correctly, this could also energize every other water fitting in the building.

I would suggest that you have this checked out immediately.

By the way, do you know the power rating (kilowatts) of the shower? These instantaneous showers have become very popular here in England, but even the smallest older units were 6kW. Such a unit designed for 127 volts would need about 47 amps of current, so the cable feeding it would need to be very heavy.
Posted By: mvp1 Re: Ground wire in Brazil - 05/01/02 03:57 AM
Thanks! What is the solution then? Should I get the ground screw in the shower and bring it with a proper wire directly to the ground? How to I make this ground? Just pushing the into the ground. How deep?
Again, many thanks. I will check the watts...
Posted By: pauluk Re: Ground wire in Brazil - 05/01/02 09:02 PM
It's getting a little complex here because I'm not familiar with the grounding arrangements in South America, and there are different systems in use (e.g. there are differences between the U.S. and U.K.). I don't know whether Brazil follows American practice or European practice, or neither. (Anyone????)

Do you not have a grounding bar at your main distribution panel? Even if most or all wall outlets are 2-prong only, there may still be a ground connection at the panel.
Posted By: mvp1 Re: Ground wire in Brazil - 05/01/02 09:50 PM
Let me study the situation here and then I will come back with more precise data. In the mean time I will keep checking if someone tries to help us. Many thanks.
Posted By: Texas_Ranger Re: Ground wire in Brazil - 05/03/02 09:28 AM
In fact in Germany it is allowed to ground to the neutral at receptacles, i.e. when you install a Schuko receptacle and only have 2 wires you cann out a jumper from neutral to ground screw at each receptacle. However, this is only Legal with old work and it can be extended using ground wire.
Posted By: pauluk Re: Ground wire in Brazil - 05/03/02 05:35 PM
Hi Texas_Ranger,

Long time, no hear, as they say.

I'm surprised this is allowed in Germany considering their high safety standards on most things.

Do they have circuit neutrals run direct to the main neutral bar, or are they allowed to have double-pole switches (breaking hot & neutral) on circuits?
Posted By: Bjarney Re: Ground wire in Brazil - 05/03/02 06:30 PM
Don’t know specifics on Brazil, but for one version of how others do it, (outside of the US) see: http://www.epanorama.net/links/wire_mains.html Scroll down to "Grounding and Earthing."

[pauluk may be able to elaborate on this.]
Posted By: pauluk Re: Ground wire in Brazil - 05/04/02 12:47 AM
There are some interesting links from that site, although I noticed a few inaccuracies on some of the websites referenced there.

The TT, TN-C etc. systems mentioned are now the standard "official" designations used in the U.K. and Europe.

The first letter indicates the type of grounding at the supply, and for all public supplies in Britain is T, meaning that one pole is permanently grounded (T for "terre" -- earth in French).

The second letter shows the type of grounding at the customer's installation: T for a connection to a local ground rod, or N for a connection to a conductor provided by the utility company.

The remaining letters, if any, indicate the arrangement of the neutral and protective ground wires of the supply: C if combined, S if separate.

Some of the systems listed correspond with the arrangements you'll find in the Technical Reference Area here.

Diagram #1 is known officially now as a TN-S system, i.e. installation ground is to a conductor provided by the power co. and the neutral and ground are kept separate throughout (except where the star-point of the xfmr is grounded, of course).

Diagram #2, our PME (Protective Multiple Earthing) system, is designated TN-C-S as the neutral/protective ground are combined on the distribution network and separate within the house.

Diagram #3 represents the TT system where the house ground is solely to a local earth rod, and the resulting high loop impedance means that a RCD (GFI) is needed.

(Diagram #4, representing a now obsolete system would also be classed as TT.)

All three of the systems TN-S, TN-C-S, and TT are used in Continental Europe.

A normal American residential service is similar to British PME, and would be classed as TN-C-S under this designation system.

[Edited for a case of "finger-trouble" typing the URL link!]


[This message has been edited by pauluk (edited 05-03-2002).]
Posted By: mvp1 Re: Ground wire in Brazil - 05/11/02 01:43 PM
More data. The electric showers here in Brazil sometimes use 8,000 watts or even more. There are two poles: one is + and the other is "neutral". The neutral is grounded at the entrance of the house (the panel). In this way the whole house is grounded there.
The showers are made of plastic but some are metal. They have three wires, one of them is the ground. They connect this ground to the neutral pole (ground) but some electrician say that they don't have to be connected noweher because there is already a neutral, ground pole...
I think I am going to put a rubber mat on the floor...
I also notice that when left on for long time the wires get a little warm...
What do you all think?
Posted By: pauluk Re: Ground wire in Brazil - 05/11/02 03:42 PM
Several points strike me here.

First, the metalwork of the shower unit MUST be grounded for safety, otherwise a fault in the heating element could energize the casing. The fact that one connection to the heater element itself is a neutral, does not remove the need for the ground on the metal casing. The "electricians" who tell you this do not seem to have a proper understanding of what is going on.

Second, even where they do connect the ground terminal on the shower, I would still not be at all happy about just grounding it to the neutral. The neutral wire may be grounded at the service entrance, but the result of a loose connection on that neutral could be lethal. The ground terminal on the shower should be run separately back to the ground busbar at the main panel.

On the power ratings, are you certain that units of 8000 watts or more are used on 120 volts? That's a very heavy load which would draw approx. 67 amps and necessitate the use of very large cable. Maybe these higher-power showers are limited to houses with 3-phase power or to those areas of Brazil where 220V supplies are usual?

Cables feeding high-power devices like this will get warm over a period of time, but whether the heat is excessive is difficult to say without actual seeing the installation.

If you can check the power rating of your particular shower and the size and length of cable feeding it, we'd be able to tell you if it's large enough or not.

I'm not sure how your cables would be sized in Brazil -- probably either AWG (American sizes) or square millimeters (European).
Posted By: mvp1 Re: Ground wire in Brazil - 05/12/02 02:40 AM
Many thanks. This is becoming interesting. One electritian told me that he could ground all three showers I have in the house. Hed also told me that I could connect them in 220 volts if I wanted and not in the 127 volts I have them now (apparently the electric wiring in the house will permit this). The way he wanted to ground each chower was to put three rods on the ground close to where the showers are and run the ground wire from each shower there. I will ask about running them to the entrance frame which is more distant. I will now look at how the wires are rated in Brazil and the distances. Yes they have 8000 watts or more, the smaller plastic ones have less and I can connect them in 127 or 220 (for some reason the electric here is 127, not 110 oe 120 - don't ask me why). Many thanks!!!
Any thoughts or suggestions will be very welcome!
Posted By: pauluk Re: Ground wire in Brazil - 05/12/02 01:22 PM
Marcio,

O.K., the information you have obtained now is very helpful and has told me the supply arrangement to your home.

The nominal 127-volt level was quite common throughout Continental Europe years ago (including Portugal, which probably accounts for its use in Brazil).

The fact that you have 220 volts available indicates that you have what is known as a 3-phase supply. These are very rare for residential use in America or Britain, but again, quite common in Europe.

Coming into your house from the street will be 4 wires: 3 phases (hot/live wires) and a neutral. Between any phase and neutral the voltage is 127V. Between any two of the three phases, you get 220V.

So for a shower designed or wired for 127V operation, it would be connected between one phase and neutral. For a shower wired for 220V use it will be connected across two phases.

The advantage of the 220V version is that for the same amount of power (watts), you need less current, so the cables can be smaller.

As for grounding each shower to its own rod, this would be effective only if the shower is fed through a device known as either a GFI (Ground Fault Interrupter) in the U.S.A., or an RCD (Residual Current Device) in the U.K. (I'm sorry I have no idea what it would be called in Portuguese.)

Without such a device, you could not get enough current to flow through the ground to blow a fuse or operate a normal circuit-breaker.

Such local grounding of a shower may be against your wiring rules (if you have any in Brazil?), but that aside it is a rather inelegant solution to the problem.

I would strongly advise you to have the showers grounded back to the main panel.
Posted By: mvp1 Re: Ground wire in Brazil - 05/12/02 10:33 PM
What a big help. Yes, this is the case: I will have a choice between 220 and 127. And yes... in 127 one pole is + and the other is neutral (ground). Then as you say, if I connect the shower on 220 I will have the two poles hot? Isn't this more dangerous?... I guess then I will have to run the ground wire from the shower independetly to the main panel. The problem is that the main panel is not to close to the showers...perhaps 15 to 20 meters. Will this be OK?... You may wonder why I am abusing your patience on these issues... but I have had so many opinions here... even from electritians...And I want to do the right thing...Perhaps one of these days you may decide to take a holiday in Brazil and take a look...(hope you will take showers...)
Regards
Marcio
Posted By: Bill Addiss Re: Ground wire in Brazil - 05/12/02 11:04 PM
Marcio,

I strongly suggest that you have a Qualified Electrician look over your installation. This is not something that we should be delving into too deeply here. We are happy to help with general safety information but must stop short of supplying detailed How-To instructions.

Good Luck,
Bill
Posted By: mvp1 Re: Ground wire in Brazil - 05/12/02 11:32 PM
Sorry if what I am doing is not allowed. But it seems that I am so close to finally having things clarified for me, after I have been searching for it for a long time (including consulting with electrical contractors and electricians here), that your intervention at this point seems very unfair to me. In case you are wondering I am not here to get anything for free. I am here because I genuinelly felt that I needed good advise in the midst of so many opinions here where I am. Regards.
Posted By: roadie Re: Ground wire in Brazil - 08/12/02 10:54 PM
Firstly, congratulations for this site!
Well, it is very interesting to find here something related to Brazil - which since 1980 doesn´t follow NEC.
The related installation - 2 wires for a 127 V electric shower - was used (officially)till 1980, because in this year was issued a new Electrical Code, (the previous one was issued in 1960) that stated for areas with humidity (kitchen, bathrooms, outside areas), the use of a 3 wire system, 1 of them exclusively for grounding (colored green with yellow stripes) and the circuit has to be protected by one residual differential circuit breaker - called "DR" - similar to your american GFCI.
But, it stated that for new erections - not to the old houses. The electric showers since that were manufactured with 3 wires, but as eletricians were used that 2 wire system for a long time, it is possible to find today a lot of houses with a 2 wire internal distribution system - including the showers circuits.
Adding this, old houses had metallic water pipes, but newer ones use plastic water pipes.
We can say that still today the "culture" is that only 2 wires are enough to "run anything". Although electricians need to get an official certificate, it is very common to find illetrate people doing residential electrical services (home owners don´t use to ask for the official certificates for such "small and low cost jobs").
Electric showers in Brazil - the highest is 5500W 127 V.
The wires in Brazil since 1980 are sized in mm2. Our code follows IEC 364.
As the previous messages say, it is necessary to take extremely care when contracting a person that calls himself as "electrician" in Brazil.

[This message has been edited by roadie (edited 08-12-2002).]

[This message has been edited by roadie (edited 08-13-2002).]
Posted By: mvp1 Re: Ground wire in Brazil - 08/13/02 12:04 AM
Yes... the sitution is like the one you described here in Brazil. Thanks to this list and the help I got here I just contracted an electritian to do things right: the connect the groung wire inthe showers to the ground on the neutral in the frame of the electric company. I am doing the same with the ground wire in computers. The old houses here still have the two holes outlets. I know that things are changing...slowly. Thanks to all of you.
Posted By: pauluk Re: Ground wire in Brazil - 08/13/02 10:09 AM
Hi Marcio,

I was thinking about your shower problem a short while ago and was wondering if you'd got it sorted out.

Roadie,
Welcome to the forum. There are quite a few of us international members here now from various places.

Maybe if you have time you could start a new thread with some general notes about the way things are done in Brazil. I'm sure it would prove interesting, as I for one am always fascinated in how systems are set up in other countries.
Posted By: SvenNYC Re: Ground wire in Brazil - 08/21/02 05:01 PM
Oh by the way,

If you want to see what a 3-prong Brazilian wall socket looks like, check it out here:
http://www.kropla.com/brazil_power.htm

It looks like a single-type American outlet (5-15) that can also accept Europlug (2 round pin) plugs in addition to the normal 3-pin American grounded plugs.

I think these outlets might also take 2-amp British Standard 546 plugs (really tiny suckers), but not the 5-amp (a bit larger) variety.

Neat configuration -- would be awesome if we could have these in the States for dual-voltage appliances! [Linked Image]

--
Sven
Posted By: SvenNYC Re: Ground wire in Brazil - 08/21/02 05:05 PM
Here is another view of a Brazilian socket when not in the wall box.
http://www.internationalconfig.com/icc6.asp?item=85110
Posted By: pauluk Re: Ground wire in Brazil - 08/21/02 08:04 PM
Quote
I think these outlets might also take 2-amp British Standard 546 plugs (really tiny suckers), but not the 5-amp (a bit larger) variety.

Other way around Sven. The British 2-pin 5A plugs are very similar to the "Euro" plug, except that the pins are slightly larger in diameter, spaced very slightly closer together, and are a fraction shorter.

This type of combination outlet, minus the grounding connection, is sometimes found on our dual-voltage shaver outlets. British shavers still come fitted with the 2-prong 5A plug.

As you say, the 2A plug is really tiny. I'll see if I can dig out some of these over the weekend and post some pics in another thread for comparison.


[This message has been edited by pauluk (edited 08-21-2002).]
Posted By: mvp1 Re: Ground wire in Brazil - 08/22/02 12:31 PM
The voltage here in Belo Horizonte is 127. Yes Pauluk I am contracting with an electritian who seems to be knowgeable. He will do what we decided, a third wire from the neutral in the electric shower conneting directed to the entrance frame neutral. But, intersting, when I told him that of the neutral of the two line where the shower neutral is conected now brakes somewhere this becomes dangerous he said NO, this will not become dangerous, NOTHING will happen except that the shower will not work... I insisted that it was dangerous and he was SURE that it wasn't...
Well, will do the work in the next few days.
Posted By: pauluk Re: Ground wire in Brazil - 08/22/02 05:30 PM
Sounds as though some Brazilian electricians need a little more theoretical training!

Glad you're getting it sorted out.
Posted By: mvp1 Re: Ground wire in Brazil - 08/22/02 11:48 PM
So glad I found the ECN. I had enormous help here and I am on the say of being able to enjoy my showers in Brazil without worries...

Many thanks!
Posted By: Trumpy Re: Ground wire in Brazil - 08/24/02 07:38 AM
I would have thought that a GFCI/
RCD, would be the first piece of equipment
fitted to an electrode-boiler type heater,
used in a damp area, regardless of how
the supply was connected.
Posted By: pauluk Re: Ground wire in Brazil - 08/24/02 10:14 AM
I don't know about NZ, but all the instant electric showers I've ever seen are regular heating elements, not electrode type.
Posted By: mvp1 Re: Ground wire in Brazil - 10/06/02 01:09 PM
Thanks to you all, especially Paul. I know have my three electric showers in Belo Horizonte, Brazil connected to the ground bar in the main entrance electric frame.

I am having happu showers...
Posted By: pauluk Re: Ground wire in Brazil - 10/08/02 05:27 PM
Marcio,

Glad to hear you've got it all sorted out safely now.

A neighbor has been refurbishing his house and I wired the new electric shower in a few weeks ago. While the bathroom was out of commission he was using a friend's bathroom just around the corner. His friend had done a lot of his own wiring (no proper grounding, bonding etc.) and he said he was glad to get his bathroom wiring done as he felt safe getting under the shower again!
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