N not behind a breaker because N-E link?

[jim234]

Please forgive me if I don't use the proper thermology, I am not a native English speaker...

 

I am familiar with 2Pole breakers where both L and N are secured. Also, E has its own circuit which runs to the copper rod outside into the ground.

 

I understand that here in Thailand 1P breakers are being used and that all N are linked in the mainboard. Also, there is an E-N link in the mainboard which confuses me. Instinctively, I feel that E can become live? After reading a few stories on this forum where E did become live, I am a bit worried.

 

Can anybody please explain to me why all N's are linked and don't go through the breakers? 

 

Is it allowed by PEA if I do use 2P breakers (so all N's are not being linked) and leave out the N-E link in the mainboard? Basically following the codes of some European countries I lived in. 

 

I did read on this forum that N-E are linked in all countries but that the actual link is not visible to the consumer. So, if I do link E with N in the mainboard, is it still ok to use 2P breakers? 

 

Thank you!

 

 

 

 

[sometimewoodworker]

You can use 2 pole breakers if you want, though you are going to have problems explaining this to the electrical installer.

 

If you are in a MEN install area the PEA will require an N-E link before installing the metre. 

Once installed you can, but should not, cut the N - E link.

 

If the PEA does an install inspection (some don’t) you must have the link. The PEA is rather unlikely to bother to check anything in the house beyond the earth link and main RCBO/main breaker. It is your responsibility to ensure that the electrical install is correct and has no problems, the PEA won’t do it for you.

 

Neutral do not need to be switched by a breaker, you are free to switch them if you want.

 

It is possible for an earth to become live for 30 milliseconds before the RCBO cuts the power.

[jim234]

Thx for your reply.

 

I am not familiar with the term MEN, I will research on it!

 

I am now comfortable with an E-N link in the main board. Found out that back home the same link is made, just not visible.

 

I didn't know that N doesn't need to be switched. In the countries I lived in, the use of 1P breakers is definitely not allowed. If N doesn't need to be switched, any idea of why 1P breakers are prohibited?

 

I don't want to overcomplicate things so I will follow the local codes. N-E link, 1p breakers and all N's connected. Just want to research a bit to make me feel more comfortable with it. 

 

 

 

[bluejets]

23 minutes ago, sometimewoodworker said:

You can use 2 pole breakers if you want, though you are going to have problems explaining this to the electrical installer.

Not if they are RCBO's..........

 

[sometimewoodworker]

54 minutes ago, jim234 said:

If N doesn't need to be switched, any idea of why 1P breakers are prohibited?

Because regulators must have something to do, is one possible answer. Another is that the way an install is done may require it in your country.

 

50 minutes ago, bluejets said:

 

1 hour ago, sometimewoodworker said:

You can use 2 pole breakers if you want, though you are going to have problems explaining this to the electrical installer.

Not if they are RCBO's..........

 

That will add to the difficulty of getting the average installer to understand.

 

NOTE I did not say electriction, because electricians are not usually found doing domestic installations.

[Crossy]

Wikipedia has a good description of the various earthing schemes in use around the world.

 

https://en.wikipedia.org/wiki/Earthing_system

 

Thailand is 3-phase, 4-wire, TNC-S with MEN (multiple earthed neutral) or PME (protective multiple earthing) in UK speak.

 

Generally, the neutral is held down near ground by the multiple grounding points (your and everyone else's local rod plus a rod at every third power pole). Problems can occur when there has been "work" done to your meter and the person has managed to swap L and N on the outgoing side.

 

There was a thread a while back where a member noticed his kitchen floor above the earth rod was getting warm. This turned out to be a reversed supply!

 

TNC-S with MEN is actually very safe (the Aussies use it and they have one of the safest electrical systems on the planet), but things can go awry when inexperienced people mess with it.

 

Back on-topic, there's nothing to stop you using 2-pole MCBs or RCBOs, but, just like the UK, it's not really necessary.

 

[unheard]

On 4/30/2023 at 8:46 AM, Crossy said:

Thailand is 3-phase, 4-wire, TNC-S with MEN (multiple earthed neutral) or PME (protective multiple earthing) in UK speak.

Is there an easy way to identify the local system by looking at utility poles?

[Crossy]

1 minute ago, unheard said:

Is there an easy way to identify the local system by looking at utility poles?

 

Checking if the neutral (usually the top wire) has a ground rod every 3rd pole is a good start.

[unheard]

28 minutes ago, Crossy said:

 

Checking if the neutral (usually the top wire) has a ground rod every 3rd pole is a good start.

As seen on high voltage lines?

Consumer voltage poles around here have 3 wires positioned at the same height:

[Crossy]

9 hours ago, unheard said:

As seen on high voltage lines?

Consumer voltage poles around here have 3 wires positioned at the same height:

 

No, those are the 25kV distribution wires which have no neutral.

 

The ones to check are lower down the pole and arranged vertically, there are usually 4 wires (3 phases plus the neutral) although some small branches may just have one phase plus neutral.

 

Something like this, note the top wire is uninsulated, this is the neutral.

 

[unheard]

14 hours ago, Crossy said:

The ones to check are lower down the pole and arranged vertically, there are usually 4 wires (3 phases plus the neutral) although some small branches may just have one phase plus neutral.

OK.

I see 3 vertically arranged wires, the top one -  uninsulated.

[Crossy]

12 minutes ago, unheard said:

OK.

I see 3 vertically arranged wires, the top one -  uninsulated.

 

Got a photo? Unusual but 2-phases plus neutral isn't impossible.

 

Part of our village actually has 5 wires, one is the feed for the street lighting (now unused as solar LED lights have been installed).

 

[unheard]

19 hours ago, Crossy said:

 

Got a photo? Unusual but 2-phases plus neutral isn't impossible.

 

Part of our village actually has 5 wires, one is the feed for the street lighting (now unused as solar LED lights have been installed).

3 wires plus another one on the opposite side.

We also have non-solar street lights attached to some poles. 

 

[bluejets]

On 5/4/2023 at 5:32 PM, unheard said:

3 wires plus another one on the opposite side.

We also have non-solar street lights attached to some poles. 

Track lines back to the transformer, there will almost certainly be a star point earth wire at that pole.