Circuit breaker vibration resistance

[SceneryDriver]

Looking at quoting a job that will require (4) 20A single-pole breakers feeding duplex Edison receptacles, all fed from a 50A or 60A 120V source. Normally, I'd just use a 4-space QO panel and not think too much about it. This job though, will require vibration resistance as the piece of machinery the panel is being mounted to will vibrate in use.

Opinions on vibration resistance of standard stab-on QO breakers? I ask about QO because I see them all the time in campers and RV's and it doesn't sound like rampant failures are occurring. Would bolt-on breakers fare better?

Anyone know if Square D makes a 4-space bolt on buss panel (space is tight)?

Suggestions for another manufacturer / approach? Fuses are out; I have little faith that a blown fuse would be replaced properly. If I fuse at 20A, I just know some muppet is going to replace it with a 30A the first time they blow a fuse.

I'm also considering DIN rail -mounted QO breakers, but this is going somewhere relatively remote, and I'm almost sure the local sparky won't be stocking those if the client needs a replacement on short notice.


Thanks,

SceneryDriver

 

[don_resqcapt19]

You have to also think about the vibration letting the mechanical latch release tripping the breaker.

 

[Jraef]

You don't really see vibration specifications for circuit breakers until you get into what are called "Naval Certified" breakers, and you pay through the nose for that.

I looked indirectly though for load centers that have what's called "OSHPD" (osh-pod) certification for use in critical infrastructure California, such as hospitals, airports etc.. OSHPD certification requires specific shake-table testing and that the equipment continues to function normally after an earthquake event as simulated on that shake table (regular "seismic certification" only requires that it not kill someone by falling on them). Load centers alone do not need OSHPD certification because they are not used in those applications, but Square D Mini Power Zones do, and they have it, using plug-on Q0 breakers.

 

[ptonsparky]

FWIW, we found that QO load centers had problems in ag situations where the panel was mounted on the bin that used high speed fans for aeration. older installs.

 

[LarryFine]

I would look for a flexible way to mount the panel, like on vibration isolators.

https://www.grainger.com/product/GRAINGER-APPROVED-Vibration-Isolator-2NPA1?

 

[FionaZuppa]

You have to also think about the vibration letting the mechanical latch release tripping the breaker.

That's what duct tape is for
It's good enough for high speed nascar, it can handle a handle from vibrating off (or on).

 

[FionaZuppa]

I would look for a flexible way to mount the panel, like on vibration isolators.

https://www.grainger.com/product/GRAINGER-APPROVED-Vibration-Isolator-2NPA1?

View attachment 2552934

These are rather rigid, probably wont swing if RV wheel hit a pothole or bump big enough to jolt the ocpd's loose or cause handle to flip off. The best way is to mount motion of handle in a different plane from bumps. Bumps are mostly vertical, so motion of handles would be best if they were horizontal. It does all depend on the internal mechanics/geometry of the ocpd of course.

I might say springs rather than a generic isolator.

 

[LarryFine]

That's what duct tape is for

'Ceptin' for the rule that holding the handle on cannot prevent a breaker from opening.

 

[FionaZuppa]

'Ceptin' for the rule that holding the handle on cannot prevent a breaker from opening.

yeah...... I know

 

[SceneryDriver]

Ugh... as much as I dislike the idea, maybe fuses are the best way to go. I'll placard everything out the wazoo, and plan to wire everything with 10ga wire. The only thing that might burn up at that point would be the duplex Edison receptacles, and they're easily replaced. Per Jaref, they certainly can't afford "Naval Certified" breakers.


Thanks,

SceneryDriver

 

[synchro]

If you do use vibration isolators then I think it would be best to put a few of them underneath the panel to support its weight, using an angle bracket if needed. Then mount the top of the panel using isolators on the back. That way you won't be putting significant shear loads on the isolators, which I don't think they are typically designed to handle.

 

[FionaZuppa]

If you do use vibration isolators then I think it would be best to put a few of them underneath the panel to support its weight, using an angle bracket if needed. Then mount the top of the panel using isolators on the back. That way you won't be putting significant shear loads on the isolators, which I don't think they are typically designed to handle.

1+n just gets stiffer and stiffer with +n isolators. If you had an angle to rest box on, I would use maybe 3/4-1" foam rubber across the angle "shelf" for panel to rest on, then use nylon locking nuts to just snug it in place (through box & angle, etc), and then maybe a undersize screw (like a #8 in a 5/16" hole) upper rear with a fender washer to allow it to move but not fall fwd.

Also remember the other issue, allowed to move around too much and you risk chaffing over time.

 

[sameguy]

What wire will you use?

 

[sameguy]

Car fuse blocks?

Miniature Circuit Breakers | Allen-Bradley

Our miniature circuit breakers are IP20 finger safe and RoHS compliant. These products also meet an expanded set of standards and certifications.

ab.rockwellautomation.com

 

[FionaZuppa]

Car fuse blocks?

Are they rated 120v ?

Fuses can be a pita, usually have to disco all the power to change one fuse, or, use a isolation tool to extract and insert the fuse.

 

[jim dungar]

Normally, I'd just use a 4-space QO panel and not think too much about it. This job though, will require vibration resistance as the piece of machinery the panel is being mounted to will vibrate in use.

Way back when, I sold QO plug on breakers to a manufacturer of crawler cranes, the dead front cover of the load center did a great job keeping the breakers on the bussing. The vibration was pretty constant, but there was little impact loading, and almost no jerking (like from an earthquake).