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| Subject - Testing an earth wire is going to ground? | |
| Westredd |
Hi guys, Hope you can advise, I am from England and I have recently moved to Brazil and have moved into an appartment here. In the fuseboard I have noticed that there isnt any incoming earth/grounding source for any earth bonding within the premises. Worrying.. Anyway, I went to install a shower, and connected live and neutral, I then noticed what appeared to be another wire that looks as though it is being used as the earth/grounding wire for the shower. I have a sneakly suspicision that this wire is not leading to a proper earth/ground source and that it is probably just snipped off somewhere else in the building, but I am unable to see where it is going. Is there any test i can do with a multimeter to verify if this wire is leading to proper earth/ground? I am very worried as the shower device has an earth wire (wired internally )that goes through the water outlet in the shower (to earth the water I presume), so my concern is that if a phase/live came into contact with this suspected loose wire within the building, it would put 220v directly into the water stream from the shower without popping the fuse, then someone walks under the shower, switches on the water and gets into a very dangerous situation. If I found that the earth wire in the wall is not connected to true earth/ground, I would think it would be safer not to connect the shower to this fake earth wire in the wall, to prevent the above scenario. So my question is, is it possibe to test this wire is going to true earth? cheers West |
| Ryan_J | I don't think you want it to go to the earth. The earth will not clear a ground fault, as it has too much impedance. Perhaps I am ignorant of your terminology, but I think what you need is some sort of a bonding conductor that goes back to the service and its grounded nuetral conductor. Before I go any further, however, I would like to know if you are an electrician. |
| Westredd | Thanks for your reply, I studied to be an electrician and am qualified, but have not been practicing for a number of years. In england, all earth bonding and earthing goes back to the same earth block where the earth service is connected. They do not have this here in Brazil and dont seem to use any earthing at all. I agree that what I need is an earth bonding conductor leading from the shower back directly to an earth block, however there isnt anything to bond it to at incoming supply point. I am pretty sure that this earth wire that has been run with the supply wires is not leading to a ground, so really my only question is how to test if it is or not (my suspicion is that you can only do it with an expensive earth impedance tester). Even though this earth wire is not in anyway sufficent as earth bonding for a shower I figurd it would be better than nothinhg, but only if it leads to ground. If it doesnt lead to ground then I think it would be better to disconnect it from the shower (for reasons given in my original post). I would call a Brazilian electrician to deal with this, but the problm is that I dont even think they know what earthing is and what it is for. The standards here are appalling. Thanks West |
| Ryan_J | Thats interesting...could you simply check continuity by (de-energized, of course) simply tying the live and earth(?) together at the shower and seeing if they are continuos at the panel? |
| Westredd | Thanks, However there isnt any earth/grounding at the panel (presume you mean the fuseboard, distribution board) for me to test continuety with. All there is at the panel is 4 circuit breakers (2 with with live/phase conductors and 2 with neutral conductors, so 2 circuits in total), no other conductors at all. Thought it was odd to have a neutrals running through a 2nd breaker on each circuit, not seen that before in the UK. Having had a 2nd closer look at the situation again this morning (from the shower end), it looks as though the earth conductor is running down (behind a tiled wall) towards the water valve for the shower. So its possible that they have just attached this earth wire to a water pipe in an attempt to bond it to ground (not good). Later , I will try to link a test wire to the shower earth conductor and run it over near where I can get the tester on an exposed water pipe to see if there is continuety between the water pipe and the earth conductor. I am also going to try and investigate the possibly of purchasing an RCD breaker which would probably be the best solution to this. Not sure if they are available here though. Just for clarity, for the earth/ground conductor we in England normally refer to it as "earth" as I think you do as "ground" in the USA. thanks West |
| Wirenutz | very interesting , at least from our perspective West, we would have a termination in the main panel called the MBJ (main bonding jumper) where neutral and earth come together This panel you've descibed seems to lack this, despite what is desribed as a bond and/or GEC (grounding electrode conductors usually end at an electrode for earthing) my question would be of the mentioned neutrals, where they originate? i'm guessing the serving x-former is center tapped here, but i understand it may not always be the RCD breakers in England are set to what ? 300ma? i've argued for years that all the bells and whistles we've grown into frankenstiens in our NEC (which lays claim it's international as of the '02 cycle) could easily be addressed by something similar here be careful West, keep on hand in yer pocket...  ~W~ |
| Westredd | As far as I am aware, the RCDs are set at 30ma. Here is a pic of this fusecupboard just so you can see exactly how it is (you need flash player to view it): http://mike722.broadphase.com/temp/FuseCupboard.html Its certainly nothing like what I have ever seen in the UK, but seems to be common around here, West |
| Wirenutz | quote: even better for the argument i would pose to have them here also , thanks as to you pix West, we certainly don't see many of those , thanks It would seem that the lower termination block (you guys don't do wire nuts right ?) would be the MBJ to us here, where our GEC would go (or your earthing wire , per se') is it possible that the meter has the earthing connection? would it be close to the panel you have shown here ? perhaps some continuity testing is possible? ~W~ |
| Westredd | quote: All the meters for the block are together at the entry point of the building (2 floors down for me). All the same again, phase and neutrals, no sign of any earthing. So you dont have RCDs in the USA? You have the plug-in type right (used with things like lawn mowers), but not the circuit breaker that fits in a fuse panel type? Why is that? cheers West |
| Wirenutz | quote: very strange indeed i would be curious to see if the plumbing reads continuity to the neutral block, which would indicate a bond somewhere quote: well yes, we've GFI's (4-6 ma) plug in variety, as well as a GFI breaker variety, a newer AFCI breaker variety i think is 30ma, every code cycle sees more of these, which is why many advocate a RCD style main here ~W~ |