I’m feeling a strange hum or light tingling feeling on my skin when I touch my computers

[Fruit Trader]

1 hour ago, Uptooyoo said:

My original post was to address the danger of grounding electrical equipment by attaching the appliance to earth (ground rod. hole drilled in the concrete floor) without using the ground wire at the receptacle. The ensuing conversation then went off the rails in so many directions. Attached is a picture showing why you must have a ground wire and not rely on an earth-only connection. The breaker will not operate to remove the lethal voltage on the appliance's frame. I AM NOT ADDRESSING GROUND FAULT PROTECTION FOR PERSONNEL! E.G. RCBO, etc.

 

Watch the first part of this video up to 2:30. https://binged.it/2Zbwf29

 

The reason why you need a ground wire.

I understand what you are saying but have one question. How would you handle this "Thai sparkies drill a hole in the floor" problem at one of the many thousands of TT installations around Thailand?  

[sometimewoodworker]

1 hour ago, Uptooyoo said:

My original post was to address the danger of grounding electrical equipment by attaching the appliance to earth (ground rod. hole drilled in the concrete floor) without using the ground wire at the receptacle. The ensuing conversation then went off the rails in so many directions. Attached is a picture showing why you must have a ground wire and not rely on an earth-only connection. The breaker will not operate to remove the lethal voltage on the appliance's frame. I AM NOT ADDRESSING GROUND FAULT PROTECTION FOR PERSONNEL! E.G. RCBO, etc.

Your post is no really relevant to the situation in all new connections in Thailand and to many older ones, specially with a non Thai in the household.

 

The reason is that they have RCCB/RCBO/RCD protection so any path to earth will trip the RCBO within 30ms

 

The over current devices are NOT designed to protect people, they are designed to protect wiring. That they may or may not incidentally protect people is irrelevant.

 

If you made clear that you are ONLY addressing a situation where there is no RCBO and that one is not going to be fitted (a situation that is becoming less and less common).

 

Your example is talking of a country that doesn't seem to appreciate the benefits of whole house RCBO protection so has to work round the lack of protection that it provides.

[bankruatsteve]

2 hours ago, sometimewoodworker said:

Your example is talking of a country that doesn't seem to appreciate the benefits of whole house RCBO protection so has to work round the lack of protection that it provides.

A front end (whole house) RCD does not work on the typical spit-phase distribution in the states.  "GFCI" is required in "wet areas" and outside outlets.  There is little, if any, risk requiring protection otherwise.

[sometimewoodworker]

21 minutes ago, bankruatsteve said:

A front end (whole house) RCD does not work on the typical spit-phase distribution in the states.  "GFCI" is required in "wet areas" and outside outlets.  There is little, if any, risk requiring protection otherwise.

If you think so.

[bankruatsteve]

1 hour ago, sometimewoodworker said:

If you think so.

Doesn't matter what you or I think.  The US NEC decides these things.

[Fruit Trader]

1 hour ago, bankruatsteve said:

A front end (whole house) RCD does not work on the typical spit-phase distribution in the states.  "GFCI" is required in "wet areas" and outside outlets.  There is little, if any, risk requiring protection otherwise.

Not sure if two phase plus neutral RCD devices are available in the US or even allowed. It would need to monitor the three lines and only break the phases.  Most panels in the US seem to provide GFCI and AFCI breakers for individual circuits.
 

[bankruatsteve]

2 minutes ago, Fruit Trader said:

Not sure if two phase plus neutral RCD devices are available in the US or even allowed. It would need to monitor the three lines and only break the phases.  Most panels in the US seem to provide GFCI and AFCI breakers for individual circuits.

I suppose an AFCI would be on a circuit but I don't think they are common.  The only place I have seen GFCI is as a point-of-use receptacle.

[sometimewoodworker]

9 minutes ago, Fruit Trader said:

Not sure if two phase plus neutral RCD devices are available in the US or even allowed. It would need to monitor the three lines and only break the phases.  Most panels in the US seem to provide GFCI and AFCI breakers for individual circuits.
 

As us 240v GFCI only monitors the 2 line conductors

[Uptooyoo]

1 hour ago, bankruatsteve said:

A front end (whole house) RCD does not work on the typical spit-phase distribution in the states.  "GFCI" is required in "wet areas" and outside outlets.  There is little, if any, risk requiring protection otherwise.

Yes. In the states, we do not use whole house protection because of nuisance trips, which may result in a setting too high for protection. We use GFCI receptacles or individual branch breakers that trip at 5 milliamps in areas where someone might come into contact between an energized conductor and ground: kitchen counter-tops, outdoor receptacles, in garages, basements, and crawl-spaces under the house. 

In Thailand the earth leakage circuit breaker is to be set at not more than 30 milliamps. That seems too high for adequate protection...see attached pictures.

[Fruit Trader]

3 minutes ago, sometimewoodworker said:

As us 240v GFCI only monitors the 2 line conductors

But where two phases and N are used it needs to monitor three lines to protect the whole system as one. I refer to post 93 - whole house protection.

[sometimewoodworker]

3 minutes ago, Fruit Trader said:

But where two phases ans N are used it needs to monitor three lines to protect the whole system as one. I refer to post 93 - whole house protection.

Either 1 phase and neutral for 120v or both "phases" for 240v

 

so possibly  3 separate GFCI's would be needed but then you are going to have fun.

[Fruit Trader]

1 minute ago, sometimewoodworker said:

Either 1 phase and neutral for 120v or both "phases" for 240v

Thats three paths which is why a whole house protection device would need to monitor current on three lines. L1-L2 L1 or L2 - N

[bankruatsteve]

In the US, a single phase from distribution goes to a "split-phase" transformer where neutral is bonded to the middle of the transformer.  I call it Live left and Live right but it's not two phases.

[sometimewoodworker]

4 minutes ago, Fruit Trader said:

Thats three paths which is why a whole house protection device would need to monitor current on three lines. L1-L2 L1 or L2 - N

Maybe that's why the US thinks that you only need to protect a few of the outlets rather than the safer whole house as in most other countries 

[sometimewoodworker]

1 hour ago, bankruatsteve said:

There is little, if any, risk requiring protection otherwise.

55555555

[Fruit Trader]

27 minutes ago, sometimewoodworker said:

As us 240v GFCI only monitors the 2 line conductors

That sits below the main isolation it is not whole house protection. 

 

And it monitors three legs.

[Uptooyoo]

4 hours ago, Fruit Trader said:

I understand what you are saying but have one question. How would you handle this "Thai sparkies drill a hole in the floor" problem at one of the many thousands of TT installations around Thailand?  

The same way I handle people who drive at night with burned out headlights and run red lights...I can't...TIT, accept or go home I guess..haha. Seriously though, I'd find a sparky who follows, at least, the Thai standards. They seem adequete...that is if they follow their own rules! 

[Crossy]

OK. I think we have gone far enough.

 

Discussion of the intricacies of the NEC and US installations really shouldn't be on a Thai based forum. Too many of our readers will only see one post and assume that's what's needed.

 

For that reason, this thread is now closed.