Would both switches [or whatever is being used to comply with 445.18(B)(2)] get wired to the same exact terminals in the controller? Or are there separate terminals for each of the switches?
Again speaking just for my company, it would be preferable that the installer utilized our solution for the requirements in 445.18(B). The reason is that our solutions are part of the NRTL files for the generators so they are not considered field modifications and do not void the listings. Technically, yes a relay or other means that has a mechanical reset could be wired in series with the internal factory control wiring for code compliance. But the new question would be, does it violate the listing?
All of the optional standby generators that are manufactured by my company have had the 2017 NEC prime mover shutdown switches factory installed on the generator since mid 2018. Before the change was made, we had prime mover shutdown kits available for installation on the generators. The kits are also part of the NRTL files.
Each manufacturer probably has their own solution, especially as it applies to optional standby. As it applies to NFPA 110, most manufacturers have a set of contacts for the installation of remote stop stations.
The company that I represent wires the 2 prime mover shutdown switches in series into the controller. If either switch is turned off, the series circuit is interrupted and controller will shutdown the generator or prevent it from ever starting. This question would be best directed to each individual manufacturer.
That is very interesting, thanks. I spoke to NFPA on this today and confirmed that the code language would allow for circuit breaker enclosures with a relay to accomplish the shutdown, provided that the arrangement complied with 445.18(B). Would you permit this type of installation to be routed to the generator controller? Or is there something that is manufacturer-specific to the generator that must be used?
Extremely interesting and valuable info. Thanks.
I concur with Brian's comments on this question.
I would also note that in the technical committee discussion on this paragraph, it was noted that the best way to make a generator set safe is to kill the engine, which makes it not only safe to work on electrically, but also mechanically. So, in the best interests of the service technician working on the system, it's probably best to use the genset manufacturer's emergency stop strategy rather than using other means that could be legal, but not as effective.
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