Replace existing wiring, circuit sizing question.

[ritelec]

In a service garage there are four lifts.

They replaced one and asked me to wire it.

They are fed with 20a-240v single phase twist lock chord drops.

The lifts have a 240v motor @ 17a

The lift has a box installed on it. The chord plug goes thru a "high limit" switch then to the motor.

The motor is NOT thermally protected.

The circuits are on 20 amp two pole breakers.


I wired the new lift as the original and the others are wired, BUT I'm thinking it should have been on a 30 amp circuit and thermal overload heaters installed.


Which would be the correct wiring?

As is, or new 30 amp circuits with motor overload protection?


Thank you.

 

[GoldDigger]

The motor load is definitely not continuous. A 20A circuit seems small if the 17A value is FLA rather than MCA.

But on intermittent use lift motors with only a spring loaded run button, it is common not to provide overload protection other than the CB. That argues for using the smaller OCPD value.

 

[Besoeker]

The motor load is definitely not continuous. A 20A circuit seems small if the 17A value is FLA rather than MCA.

But on intermittent use lift motors with only a spring loaded run button, it is common not to provide overload protection other than the CB. That argues for using the smaller OCPD value.

Not really my field but we have done a few man riding cargo hoists at an airport. There was overload detection but used for fault indication only.
We also did some VSDs that provided back up as emergency duty fire pumps. They switched to fixed speed with no overcurrent protection. Better to risk the motor and save the building was how I saw it.

 

[ritelec]

thank you........