I live in Indonesia, the voltage for residential buildings ranges from 220 V to 230 V, I need help with the installation of the Schneider products. Here is the link to the thread about the installation of Surge Arrester in Picture 1, which is related to the installation discussed in this thread:

Power Source Box and SPD Box Surge Arrester A9L15687 and its dedicated external Short Circuit Protection Device A9K24240


Some wires in the pictures might not represent the real wiring. They are drawn running through available white spaces so that it is easier to check the wiring in the picture. In the real installation, these wires are shorter as they can run behind the components.


In my neighbourhood, power cables are running over streets making them prone to being disturbed by falling trees or traffic. Brownouts are possible. Blackouts can happen once a month and the duration can be very long or very short. Sometimes, after the power recovers, it turns off again less than ONE second later before turning on again a few seconds later. When the power is on and the use of power is in its full load, the main MCB (1) in Picture 1 will trip. There is not enough time to disconnect the electronics to prevent this. Air Conditioners and refrigerators in the house have the inverter technology which some technicians claim that they are susceptible to power surges and unstable voltage.

Hopefully, the use of ON-Delay Relays and Undervoltage and Overvoltage Relay in Picture 3, combined with a servo motor voltage regulator and APC Surge Protectors PM1W-GR will help wereduce the damage.


  1. Are there any mistakes in the wiring in Picture 2 and 3?

  2. In Picture 3, each contactor, labelled 15, 18, 22, has two different ratings, AC-7a for resistive loads or slight inductive loads and AC-7b for inductive loads . Because one contactor is connected to the combination of lights (resistive loads), air conditioners and refrigerators (inductive loads), the rating of AC-7b is used. Is this correct?

  3. In Picture 3, relay 19 and 21 have the maximum switching current of 8 A while the value for relay 17 is 5 A. Does these relays work with the contactors marked 15, 18, 22? I cannot find the data that tells the maximum current drawn from these contactors' coils.

  4. The maximum house subscription power is 4400 VA, with the voltage of 220 V, the maximum current is 20 A. In Picture 2, is it safe to use an RCCD rated 40 A combined with an MCB rated 20 A?

In Picture 2, a combination of an RCCD (7) and an MCB (8) are used instead of an RCBO to save costs as it is cheaper to replace an MCB rather than an RCBO when the maximum power is upgraded in the future.

  1. I am aware that some components might not be needed such as the use of another RCCB (13) in Picture 3 in addition to an RCCB (7) installed in Picture 2. Apart from being redundant, does it have any negative effects?

  2. To save costs, one RCCB is used to control the whole circuit. I know that this is not the best practice as each protected electronic should be connected to one RCCB. Is there anything wrong with this approach? Picture 1 Picture 2 Picture 3

  • 1
    In your "New MCB Box" diagram, you define red as hot and blue as neutral. Are we to presume yellow is ground?
    – FreeMan
    Jan 21, 2022 at 13:44
  • Yes, yellow is ground. Thank you for the response :) Jan 23, 2022 at 2:13


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