Is safety relay a NFPA79 requirement for E-stop circuits?
Is safety relay a NFPA79 requirement for E-stop circuits?
(OP)
I am confused about whether a safety relay is required in an emergency stop circuit. I recently had a salesman tell me that NFPA 79 requires a level of control reliability for an E-stop that is essentially Category 3. If this is the truth, can someone point me towards the sections of code that imply this?
I agree that it is good practice to use a safety relay. However we currently have some machines that have low levels of risk. The E-stop button opens a single contactor on the line side of the drives. Is this an acceptable practice according to NFPA 79? Or is the use of a safety relay implied for all E-stop applications?
Sorry if this is a common topic for discussion. I tried to browse the many old threads about emergency stop circuits but I didn't see anything that addresses my specific question. Thanks.
I agree that it is good practice to use a safety relay. However we currently have some machines that have low levels of risk. The E-stop button opens a single contactor on the line side of the drives. Is this an acceptable practice according to NFPA 79? Or is the use of a safety relay implied for all E-stop applications?
Sorry if this is a common topic for discussion. I tried to browse the many old threads about emergency stop circuits but I didn't see anything that addresses my specific question. Thanks.





RE: Is safety relay a NFPA79 requirement for E-stop circuits?
RE: Is safety relay a NFPA79 requirement for E-stop circuits?
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You may study paragraph 9.2.5.4.1 Emergency Stop. It does not states that every machine has category 3 risk. It requesting that risk assesement needs to be perfromed. Based on this proper emergency stop configuration needs to be selected.
PaulBr.