OT...Industrial Circuit breaker/Manual Motor Controller/Supplementary Protector

[XtremeIN]

Hello all,

Basically what are the differences? At one time we were using an AB 1492-CB3 MMC/SP, then we started using an AB 1489-A3D ICB. The reason being UL489 code. But I cannot get an answer if we have to be UL489. We use them as a secondary circuit protector and a manual shut off to service the machine. I am not an electrician; we do not wire the service that the machines are hooked up to. They are similar to any circuit, a circuit breaker in the main panel to a disconnect box to the machine. Any information/insight would be great.

Thanks,
Micheal

 

[ndzied1]

I'm not sure of what your application is so I can't say too much but a UL489 circuit breaker is allowed to be used to provide short circuit protection for a branch circuit.

A UL1077 supplimentary circuit breaker is NOT allowed to be used to provide short circuit protection for a branch circuit.

When you talk about a manual shut off to service an entire machine, you are talking about a main disconnect. There are other requirements for a main disconnect switch. I can't tell if you are shutting off the supply into the machine or just a section of the machine with the device.

 

[kamenges]

This is simplifying the situation quite a bit but a supplementary protector is intended to be used as additional protection for sensitive devices. A UL489 device must be used prior to the supplementary protector and must be sized to adequately protect the circuit.

the biggest difference is that UL489 breakers have been carefully evaluated and there is a high degree of certainty that they will operate as designed and tested. A UL1077 supplemental protector, on the other hand, has not been evaluated to the exacting standards. So while we expect it to correctly protect the circuit and it will most likely protect the circuit there is not the same level of certainty that it will.

If you are using a UL1077 device to isolate a circuit that is already adequately protected by a UL489 device and the extra overcurrent protection is just a bonus you are in good shape. But as Norm stated a UL1077 device cannot act as a branch circuit protector.

Keith