I am using Havells Changeover for switching between generator and main supply. There are three slots.

  • Main
  • Gen
  • Load

Main has two Neutral wire, Gen has one, but Load has no Neutral wire.

When system is on Main power, it works fine. but when Generator is started i don't get electricity in house.

Lights blinks a little whole time.

Is it due to missing neutral wire in Load?

Should i remove one wire from Main and put in the Load? are all neutral wires same, or there is some difference

  • 1
    \$\begingroup\$ There are two inputs, MAINS and GEN. LOAD is an output. Make a schematic of how you have wired it up as your description is very poor. There is a schematic button on the editor toolbar. Please use capital letters on the start of each sentence as in standard English. \$\endgroup\$
    – Transistor
    Jun 6, 2016 at 14:27
  • \$\begingroup\$ "Main has two Neutral wire", what for? \$\endgroup\$ Jun 6, 2016 at 14:59
  • \$\begingroup\$ I have improved my question, electrician combined two neutral wires into main, which i also think not correct. \$\endgroup\$
    – Techmaster
    Jun 6, 2016 at 15:57

2 Answers 2



simulate this circuit – Schematic created using CircuitLab

Figure 1. SPN 30 changeover unit wiring.

Wiring is very straight-forward as shown in Figure 1.

I have improved my question, electrician combined two neutral wires into main, which i also think not correct.

Ask your electrician why he did this. You haven't supplied a photo or a wiring schematic so any comments would only be guesses.

  • \$\begingroup\$ Which of neutral wire's other terminal should be connected to ELCB? \$\endgroup\$
    – Techmaster
    Jun 6, 2016 at 17:10
  • \$\begingroup\$ One of neutral wire's one end is connected to ELCB & other to main of device in question. If that is right other wire should go to Load or vice versa. \$\endgroup\$
    – Techmaster
    Jun 6, 2016 at 17:16
  • \$\begingroup\$ How do you think I could possibly give advice based on your description? You are looking at the wires. I can't see them. I don't know where they go. If you'd like to add a schematic as suggested then maybe we can help further. \$\endgroup\$
    – Transistor
    Jun 6, 2016 at 17:44

In the picture you linked, it shows that Main, Generator, and Load each have Line and Neutral terminals. How do you figure that Main has two Neutral terminals?

  • \$\begingroup\$ MAIN has only one slot, but in my system it is having two neutral wires. \$\endgroup\$
    – Techmaster
    Jun 6, 2016 at 16:00
  • \$\begingroup\$ Should i remove one neutral wire and put in load? \$\endgroup\$
    – Techmaster
    Jun 6, 2016 at 16:02
  • 2
    \$\begingroup\$ You should determine which of the two wires in the Main Neutral terminal really goes to the load, and move it to the Load Neutral terminal (if you move the wrong wire, things probably won't work.) \$\endgroup\$ Jun 6, 2016 at 16:04
  • \$\begingroup\$ So you mean load neutral and main neutral wires are functionally different? \$\endgroup\$
    – Techmaster
    Jun 6, 2016 at 16:09
  • \$\begingroup\$ From your description, the Main and Load neutrals are apparently not connected other than at this switch, but I can't be sure without examining your wiring. If the thing does not operate as required, get the electrician who installed it to come back and corrrect his work. \$\endgroup\$ Jun 6, 2016 at 16:34

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