Tom Rees wrote: ... I have no idea what he is talking about.
"The 100 amp breaker does not need a retaining clip, because it is loaded out to the 80%/125% rule per the NEC."
Tom,
That electrical contractor does not know what he is talking about either.
408.36(D) Back-Fed Devices. Plug-in-type overcurrent protection devices or plug-in type main lug assemblies that are backfed and used to terminate field-installed ungrounded supply conductors shall be secured in place by an additional fastener that requires other than a pull to release the device from the mounting on the panel.
No exceptions given.
Explain it to that contractor this way: feed that breaker with 240 volts limited to 5 amps (which is well within what the contractor is stating), switch the breaker off, pull that plug-in-type breaker from the panel board (while accidentally switching the breaker back on), now touch the conductor terminals, or, better yet, touch the plug-in contacts accidentally ... I'll stand back so I can catch you on the first bounce after you hit the floor from recoil from the electrical shock you will receive.
Or, a simpler way is to ask him is like this: Are you saying that, "because it is loaded out to the 80%/125%", that you can safely touch the terminals the supply conductors terminate into, and touch the plug-in contacts to the bus bar with the breaker plugged in? That is the just as safe as unplugging the plug-in breaker. I'd like you to show me how you do that.
The saying is "Can't fix stupid" ... maybe 'stupid can fix itself' by touching that while energized. (The breaker being "off" still does not de-energize the supply to the breaker, only de-energizes the contacts to the bus bar.)
Then ask him to show you the "rule per the NEC" which contains the exception to the hold-down requirement for back-fed overcurrent devices.
I'd like to know that NEC rule also (it doesn't exist that I know of).
Posted: Thu Nov 12, 2020 12:28 pm