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?
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.
Re: Ground wire in Brazil#133488 04/29/0208:09 PM04/29/0208:09 PM
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...
Re: Ground wire in Brazil#133489 04/30/0201:46 PM04/30/0201:46 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.
Re: Ground wire in Brazil#133490 04/30/0211:57 PM04/30/0211:57 PM
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...
Re: Ground wire in Brazil#133491 05/01/0205:02 PM05/01/0205:02 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.
Re: Ground wire in Brazil#133492 05/01/0205:50 PM05/01/0205:50 PM
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.
Re: Ground wire in Brazil#133494 05/03/0201:35 PM05/03/0201:35 PM