LOTO for Split AC Systems

[jtinge]

Consider a split system air conditioner, with an indoor air handling unit and outdoor condensing unit, each supplied with their own 50 volts or greater energy source, and interconnected electrically only by "less than 50 volts" control wiring.

To work on either unit, do you treat each unit separately with one electrical energy source that requires simple LOTO or do you treat as a system with multiple energy sources (including non-electrical energy sources) and use a more complex LOTO procedure?

 

[goldstar]

Interestingly enough I just had this conversation with some of my colleagues yesterday. Make sure you read the mfr's instructions. Some of them require a separate disconnect at the evaporator unit. In that case you won't need a separate LOTO. Otherwise, the power to the evaporator originates at the condenser unit and you will have to use the LOTO there.