Question 1

What is the difference between an isolator and an MCB?

Accepted Answer

An isolator is a manual on/off switch — it does not trip on overload. Its job is to safely disconnect a circuit for maintenance. An MCB trips automatically on overload or short circuit. Most home DBs use an isolator as the main switch upstream of the RCCB and MCBs.

Question 2

Do I need an isolator before the energy meter or after?

Accepted Answer

KSEB does not allow consumer-side switches before their meter. The isolator goes after the meter, immediately upstream of your distribution board. This lets you cut all power to the home for safe panel work without involving KSEB.

Question 3

What rating isolator should I choose for a home?

Accepted Answer

Match the isolator rating to your sanctioned KSEB load. A typical Kollam home with a 5 kW single-phase connection uses a 40 A or 63 A DP isolator. 3-phase 8 kW connections use a 63 A or 100 A FP isolator. Always one step up from the load — never below.

Isolators & Changeover Switches

Pole Configurations

Double Pole (DP)

Triple Pole (TP)

Four Pole (FP)

Changeover Switches

Tell us your sanctioned load we'll size the isolator.