New House - Strange Breaker Box Wiring

[maxpower]

2 hours ago, bankruatsteve said:

The structure steel should be "bonded" to earth internally (via the rebar in the concrete).  I haven't seen where additional bonding to earth stakes is required.

To avoid confusion, I suggest you study the difference between bonding and earthing. A steel roof structure whose only path to ground is via structural rebar is not bonded. To form a bond, a connection would be made between said structure and the buildings common electrical ground. These bonds keep all exposed metalwork at a the same potential.

[bankruatsteve]

7 minutes ago, maxpower said:

To avoid confusion, I suggest you study the difference between bonding and earthing. A steel roof structure whose only path to ground is via structural rebar is not bonded. To form a bond, a connection would be made between said structure and the buildings common electrical ground. These bonds keep all exposed metalwork at a the same potential.

Study?  Been there, done that.  But thanks for the concern.  I was just using the same term as the poster who has already "bonded" his CU earth to the structure.  Cheers.

[Crossy]

OK chaps, a couple of posts have been removed.

 

Let's play nicely shall we?

 

[MrDetUdom]

On 11/14/2017 at 5:12 PM, RichCor said:

I'm was a bit worried about the ~12-13v differential the poster was writing about in the shower. Was that measurement taken from the water Heater NEUTRAL and Heater GROUND to the wet floor? Ouch!

Yeah, this voltage was between the water heater ground and the wet floor. (Or actually, between the hot/cold water mixer and me holding the other multimeter electrode while standing on wet floor). It wasn't like this when the house was finished, but has appeared gradually. (It first became noticeable after we got an air conditioner installed, which led me down the false path of thinking that was the issue).

 

Basically, the house was built during the rainy season (although it was originally supposed to have been finished before the rainy season started), and we have around 1 m of backfill on the original land level. (The original land was marshy). So when the house was first built, all of the rebar in the walls would have been in good conductive contact with the ground water in the soil under the house, which also had the earth spike put in by the builder. At this point, I think we had a good earth connection and the structural steel was effectively "bonded" (I don't know if this is right term) via the wet soil under the house.

 

However, as the dry season has progressed, all of this water has dried up/drained out. This has broken the electrical connection between the rebar, the earth spike, and the local electrical earth level. Since the original earth spike is underneath the middle of the house, it's not really going to get any more water. So it is basically useless as an earth spike. I guess it will begin to function again when the rainy season starts up again next year. I put in a new earth spike that is deeper and that is also outside where the soil will get when rained on, but it also doesn't appear to have a very good electrical connection. I think the entire region here just becomes dry as a bone during the dry season.

 

For the "bonding" that I did in the roof, I didn't actually connect to the roof or rebar (which are welded together and have been painted with some kind of coating). I connected to the reinforcing wire that they use in the concrete block walls. I only connected to the ones sticking up around the bathroom. Because of the poor grounding here, my guess is that instead of dragging the house voltage down to ground level, this is actually pulling the entire house voltage up to neutral (which gets up to around 20V when the water heater is on). Anyway, it fixes the tingle in the bathroom.

 

For the actual roof itself, I wasn't sure what to do. It seems like connecting that to the earth via the CU would create a problem in case of lightning strike? I don't know if that is a valid concern, but we do have one of the taller buildings in the neighborhood. Presumably there is now a conductive path that goes: roof -> rebar in walls -> concrete wall -> reinforcing wire in walls -> earth wire -> CU -> earth spike. Given the poor earth connection, I was thinking of driving another couple of earth spikes at different points around the house. If I connected one of those up to the roof metal, it would provide a lightning conduction path as well as hopefully getting a better ground connection than we have.

[bankruatsteve]

When mysterious events happen with the electric here, there's usually some ants and/or geckos involved.  You should check all outside boxes, lights, etc.  If that doesn't turn up anything, look for likely places inside.

 

I don't think you should worry too much about your ground.  It is not likely to lose it just because things got dry.  If you were on desert sand, maybe - but you're not.