Electrical Safety in Bangkok Apartment

[smokinfun]

Hi,

I've got the steps for a house (you rich folks); but us poor sobs who rent an apartment need a more portable solution. The steps for a house:

1. Safe-T-Cut RCBO- install before your subpanel in apartment; can take out when move out.

2. Earthing with 2.4 m rod - so run wire down to ground; difficult on 7th floor (but just cost; not impossible)

3. MEN connection - in apartment would have to re-wire to run neutral through Earth bar

4. Safe-T-Cut RCBO circuit breakers - probably not want to invest for apartment

I've tracked my electricity supply to the closet in the hall - a meter for every room. But I don't see any ground - everything is 2 wires. I know the Air conditioner has potential on the case - it's now a 'no touch' area. My Apple laptop (aluminum case) is also giving me a jolt now and then. Step one is easy (except for parting with 5000 THB at HomePro for the 100mA one); steps after that would like advice. I have a multitester and can do simple repairs to electronics (which fry lots here); but not sure about the earthing rod and if a wire running 7 floors would have to be huge.

Thanks so much to all on these threads; some posters talked about danger with electricity (very true); but discussing solutions on the forum is okay IMHO. I appreciated the post - it is very good. Thanks for the time with this one.

[smokinfun]

Here's a picture of the subpanel in my room. The yellow wire is not a 'ground' - I noticed that they only have 2 strand romex; so got some yellow and when the 'electrician' went to work I told him to add ground to fixture - he did from fixture to subpanel but there it ends.

[Crossy]

Ah, the dreaded 2-wire apartment

Is there anywhere you can access the building steel? Possibly in the ceiling space or the pipe shaft, if your incoming water pipe is galvanised steel that should give a good ground, but don't use the fire sprinkler pipe.

Failing that your balcony railing should provide a good enough ground to remove the 'tickle' from the A/C and your PC, but without a Safe-T-Cut won't give you a safe installation.

Ask your landlord about installing a Safe-T-Cut, maybe offer to split the cost and leave a safe place for the next occupant.

[lopburi3]

Although have never lived in apartment building have been told that there should always be access to good ground in elevator shaft, Believe they require.

[cigar7]

I ran a ground wire from the main breaker box in my condo to exposed rebar in the electric distribution, where the meter is located. Look in the main meter room for exposed building steel.

Edited November 26, 2015 by cigar7

[bankruatsteve]

So, you know that having ground to your CU and doesn't continue to your plug receptacles is useless, yah? Or, what would be the plan to do that (carry on to the plugs)? Unless you have class-1 device, ground really isn't that important. And MEN, in my opinion, doesn't help/hinder any normal installation in Thailand. IE: use MEN or not - no difference.

[Forkinhades]

^ sorry Steve, but a MEN connection makes a huge difference.

Main reason is that with a MEN connection, your impedance value of the circuit is lowered considerably, and under fault conditions 'can' open MCB's, thus in theory a Safety-cut device is not required. Although I strongly advise NOT to rely on that set up, and indeed adhere to thai regulations.

However with a MEN connection, you are also relying that the supply from the PEA has indeed been grounded, or you run risk of fault currents from 'others' going through your Fuse Box. That's another scary thought.

I have seen installations here in LOS, that work well, with just the MEN connection and NO earth going away but with earths at the sockets. Again I do not recommend it, and indeed I repeat you should have your installation done as per the thai regs.

[bankruatsteve]

Forky, can you explain further: What is the circuit that impedance value is lowered with MEN? And, with no earth, how is MEN implemented?

[Crossy]

It's worth looking at this Wiki page https://en.wikipedia.org/wiki/Earthing_system for discussion of the various earthing systems in use.

Thailand is supposed to be TN-C-S with MEN (called PME in the UK) or TT. There are reports of some villages being IT, but I suspect this is actually a failed star-point ground rather than a deliberate action.

One point to note, unless you KNOW that MEN is implemented in your area do not link neutral and ground leave it as TT, as Forky notes you could end up with the whole village neutral current returning via your ground spike.

[Forkinhades]

@Steve

Typically the ohmic value of a Earth Rod is around 20 ohms, and I will use this value as the example.

So all your final circuits will have values over 20 ohms, so in fault conditions with ONLY MCBs installed they will NOT open in the TIME required by any regs, indeed may not ever open. Ohms law tells us this. So this is why we install a Safety-cut device which only requires 30mA of fault current to open.

With MEN installed, your earth value will be lowered, mine for example was lowered to 0.5 ohms (measured). So now under fault conditions there is enough current to open the MCB's in the TIME specified. Again ohms law tells us this.

NOTE: MCBs in Thailand are mainly type C, which basically means they can handle 10 x nominal current, so a 32Amp can handle 320A!, and indeed require such fault currents to open the MCBs in the TIME specified.

If you install MEN without a main ground, you are solely relying on the PEA, and the building arrangements for your earth. Which is ok ( debatable ), so when you install final earth cables, you should indeed have an earth. This would have to be measured.

[bankruatsteve]

OK - so you are describing a fault circuit, right? I'm still scratching to see where MEN helps anything when the recommendation and requirement (?) is to have front-end RCD. Given that, it just seems somewhat more risk to implement MEN than not unless sure everyone else is doing same. Cheers.

[Forkinhades]

As per Thai regs a front end Safety-cut is required.

The benefit of MEN, is that your MCBs will open if your Safety-cut device fails. Thus giving belt and braces effect.

[Forkinhades]

^ more importantly it is a requirement of the PEA