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Safe-T-Cut consumer unit - factory-wired.

Featured Replies

Disclaimer: I am not a licensed electrician.

I recently purchased a new Safe-T-Cut consumer unit (CU) and would appreciate expert feedback regarding its factory-wired connection between the Ground (Earth) bus-bar and the RCBO’s Neutral (N) terminal.

This CU will serve as my main distribution board. It already includes a separate Neutral bus-bar located in the lower right corner. However, the existing factory wiring appears to bypass this Neutral bar, connecting the Ground bus-bar directly to the RCBO’s Neutral terminal instead.

Additionally, the Thai-English diagram that has been distributed widely shows a different setup altogether: the Bonding Conductor from the Ground bus-bar connects to the RCBO, and then from the RCBO, it connects to the Neutral bus-bar. This setup has left me a little bewildered and confused.

My questions are:

Is the current factory-wired connection correct and compliant with local standards?

Should the cable from the RCBO’s “N” terminal be disconnected and instead connected directly between the Ground bus-bar and Neutral bus-bar to ensure proper MEN (Multiple Earthed Neutral) configuration?

Any insight from qualified electricians or those familiar with Safe-T-Cut distribution boards would be much appreciated.

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I did have to look twice, but it is correct.

 

That bar (sitting on a black insulator) is the outgoing neutral rather than earth (earth is the one at bottom right of the box). It is marked as Neutral output.

 

For Thai MEN as in the drawing the incoming neutral goes via the earth bar (bottom right of the box) which is securely bolted to the metal case.

 

I assume the bar bottom right is actually marked as Earth.

"I don't want to know why you can't. I want to know how you can!"

  • Author
1 hour ago, Crossy said:

I assume the bar bottom right is actually marked as Earth.

You are correct — there is indeed an earth symbol beside the bottom bar.

According to the wiring diagram, the RCBO is shown as connecting to the Neutral bus-bar, but in practice, there’s no clear indication that such a connection exists. In fact, as shown in the photo, there appears to be only one connection from the RCBO.

Also, can you please confirm whether the bottom bar is still designated as the Neutral bus-bar, and the top bar as the Ground (Earth) bus-bar?

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I think, the main N goes to the bottom E bar. Then, a link from the E (bottom right) to the main input N (Main breaker)

The top Bar is the N (neutral) and the bottom right is the E Earth. A gound rod should be connected to the bottom right.

But, please wait for @Crossy to confirm before connecting antyhing.

The bottom bar on your CU is earth as marked..

 

The top bar is Neutral out as marked.

 

It's just a different physical arrangement to that in the diagram, not a different electrical arrangement.

 

The incoming neutral from your supply goes first to the bottom (earth) bar, then to the neutral input of the main breaker. Just like the diagram.

 

The incoming live goes strainght to the main breaker.

 

Isn't there a connection diagram with the CU??

 

@stubuzz is correct.

 

 

"I don't want to know why you can't. I want to know how you can!"

Should you also check that a MEN link is the correct configuration in your area? 

3 minutes ago, stubuzz said:

Should you also check that a MEN link is the correct configuration in your area? 

 

Good point, most areas are now upgraded anyway.

 

But a check that the neutral is earthed every 3rd pole or so can't hurt.

 

"I don't want to know why you can't. I want to know how you can!"

  • Author
11 hours ago, Crossy said:

The bottom bar on your CU is earth as marked..

 

The top bar is Neutral out as marked.

 

It's just a different physical arrangement to that in the diagram, not a different electrical arrangement.

 

The incoming neutral from your supply goes first to the bottom (earth) bar, then to the neutral input of the main breaker. Just like the diagram.

 

The incoming live goes strainght to the main breaker.

 

Isn't there a connection diagram with the CU??

 

@stubuzz is correct.

 

 

 

11 hours ago, Crossy said:

 

Good point, most areas are now upgraded anyway.

 

But a check that the neutral is earthed every 3rd pole or so can't hurt.

 

Thank you for clarifying that the diagram does not necessarily represent all consumer units available in Thailand. Unfortunately, my Safe-T-Cut CU was supplied without a wiring diagram, which added to my confusion.

If I may, I have a couple of follow-up questions:

According to the standard wiring diagram, the RCBO appears to connect to both the Neutral bus-bar and the Ground (Earth) bus-bar. However, in my CU, the RCBO seems to be connected only to the Neutral bus-bar. Should this be corrected, or is it safe to operate the CU without a connection from the RCBO to the Ground bus-bar?

Regarding verification of the MEN configuration - do you have any suggestions on how to confirm whether the neutral is earthed at the supply pole in my area? Would providing some photos of the supply poles assist in determining this?

Assuming you are MEN the incoming neutral goes first to the earth bar and then the RCBO input N. Incoming live goes straight to RCBO input L.

 

By far the easiest way to check if your area is MEN is to take a walk and look at your power poles. You should see a conductor going from the neutral (usually bare and the top wire) doen the pole to a rod in the ground.

 

Not wiring MEN would make your installation TT, with an RCBO not really hazardous but MEN is more resiliant.

"I don't want to know why you can't. I want to know how you can!"

On 11/6/2025 at 2:40 AM, Crossy said:

Not wiring MEN would make your installation TT,

Should a local ground rod be connected to the consumer unit?

10 minutes ago, stubuzz said:

Should a local ground rod be connected to the consumer unit?

Yes.

  • Author
On 11/5/2025 at 5:21 PM, Crossy said:

The bottom bar on your CU is earth as marked..

 

The top bar is Neutral out as marked.

 

It's just a different physical arrangement to that in the diagram, not a different electrical arrangement.

 

The incoming neutral from your supply goes first to the bottom (earth) bar, then to the neutral input of the main breaker. Just like the diagram.

 

The incoming live goes strainght to the main breaker.

 

Isn't there a connection diagram with the CU??

 

@stubuzz is correct.

 

 

 

On 11/6/2025 at 6:40 AM, Crossy said:

Assuming you are MEN the incoming neutral goes first to the earth bar and then the RCBO input N. Incoming live goes straight to RCBO input L.

 

By far the easiest way to check if your area is MEN is to take a walk and look at your power poles. You should see a conductor going from the neutral (usually bare and the top wire) doen the pole to a rod in the ground.

 

Not wiring MEN would make your installation TT, with an RCBO not really hazardous but MEN is more resiliant.

The local village electrician confirmed that the Neutral is earthed at some of the electricity supply poles in my area thus complying with MEN – the Neutral is earthed every 5th pole though.

I also obtained a connection and wiring diagram, which is enclosed in this message but I’m unsure how to interpret it.

Therefore and if I read the previous posts correctly, my Safe-T-Cut CU should be wired as follows:

Live (L) from the electricity pole straight to the input (L) connection of the MAIN Breaker.

Neutral (N) from the electricity pole to the Ground/Earth bar, then a link to the MAIN breaker N connection.

I would greatly appreciate a nod of approval.

IMG 3.jpg

Your description is correct, your sparks should know this.

 

The diagram you have shows the internal wiring of the unit rather than how to connect it in Thailand.

 

Do verify that the supply polarity is correct (what you think is L really is L).

"I don't want to know why you can't. I want to know how you can!"

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