Hi all,
I have friends who does live music events in different rented venues throughout the country. Electrical safety has (no surprise there) not really been important to them all. I have helped them improve this by designing some mobile Distribution board with a main breaker, circuit breakers (with a reasonable current rating) and PowerCon outlets. I also helped them purchase good quality 3-core cables with sufficient dimensions and make sure that their outlets and rigs are properly grounded. I feel reasonably confident that the part of the electrical system that they bring and install themselves is reasonably safe (much safer than it was before anyway). Now, the issue is always the connection point in these rented venues. Usually they consist of a massive 125 or 200A breaker just placed in the open on a wall behind the stage area. Not much we can do about this, just have to train the guys to be as careful as they can when connecting to it. However, a question was raised how to connect to these main breaker in cases where there is no dedicated bus bar for the ground connection. In some cases there are 2 bus bars, 1 ground and 1 neutral, but many times it is simply 3 phase and 1 neutral wire coming in to these boards or 1 phase, 1 neutral.
I understand that Thailand can be a mix of different supply types like TT, TN-C-S with MEN etc. depending on where in the country, when the venue was built etc. This is all a mystery to me still as I am used to Scandinavian standards meaning either TN-C or TN-S, nothing else. In my understanding, IF these connections point in the venues were TN-C supplies you would connect both your ground wire and neutral wire to the PEN bus bar. If it was TN-S you would connect the ground to the PE bus bar and the neutral to the N bus bar, simple as that.
Now to my question. Does this apply in Thailand as well even if they are using TT or TN-C-S with MEN? If I see a main breaker box behind stage with a 3-phase supply to the breaker and a single wire connected to a bus bar above the breaker, do they connect both their Neutral and Ground wire to this bus bar just as if it was a TN-C supply?
I should add that there they never get access or a chance to inspect to the main DB, only the connection points described above. Also, the venue technicians usually has no clue whatsoever.
I guess my question comes down to: If I tell them to always put neutral and ground together on the same bus bar in cases where there is only 1 bus bar, is that always safe or could it lead to something dangerous? Of course they still need to use a meter to confirm that the breaker box is not wired up in a weird way and that the neutral bar is indeed the neutral bar etc.
Sorry for a long a confusing post, hopefully someone is able to help me😄
