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Do you re tighten your circuit breakers and plugs?
Miguel Magalhães:
Hi everyone,
Many years ago I had my power distribution box (63 Amp Three Phase) doing fireworks in the middle of an event and it was a scary and stressful situation because where it was plugged, wasn’t easily accessible so it took sometime to shut it off.
I was in shock because I always do my math and never over power my cables or the total capacity of circuit breakers or the main switch which was near maximum that night.
One option for this nightmare could be some loose screws in the circuit breakers due to moving the box around. A coligue said he would every now and then re tighten all the screws in his power boxes. It maked total sense in stuff that is traveling in a van.
And I was questioning myself if makes sense to do that also to the three phase extension cables.
What I don’t understand is why my power distribution box slowly caught fire and no circuit breaker went off. Shouldn’t they shut down with excessive heat?
Anyways, what’s good practice in your opinion?
Chris Hindle:
--- Quote from: Miguel Magalhães on June 13, 2022, 12:16:42 AM ---Hi everyone,
Many years ago I had my power distribution box (63 Amp Three Phase) doing fireworks in the middle of an event and it was a scary and stressful situation because where it was plugged, wasn’t easily accessible so it took sometime to shut it off.
I was in shock because I always do my math and never over power my cables or the total capacity of circuit breakers or the main switch which was near maximum that night.
One option for this nightmare could be some loose screws in the circuit breakers due to moving the box around. A coligue said he would every now and then re tighten all the screws in his power boxes. It maked total sense in stuff that is traveling in a van.
And I was questioning myself if makes sense to do that also to the three phase extension cables.
What I don’t understand is why my power distribution box slowly caught fire and no circuit breaker went off. Shouldn’t they shut down with excessive heat?
Anyways, what’s good practice in your opinion?
--- End quote ---
Heat doesn't trip a breaker. Over-current does.
Loose wires create heat, heat is not your friend.
Part of yearly maintenance is opening everything up and tightening screws.
Distro, custom extensions, and every cable that doesn't have a molded plug/socket.
Include the SpeakOns and PowerCons in this procedure.
Open up all the amps, Vacuum all the hidden corners, fans, filters, blow out the gunk that collects on the heat sinks. An old toothbrush is really good at this....
Chris.
Keith Broughton:
Tightening screws on portable panels and cables is a good idea.
Brian Jojade:
Properly tightened screws in a proper panel shouldn't require regular tightening.
Now, if you're using a power distro panel that isn't designed for road use (ie, a homemade distro) then it's much more likely that things can shake loose in the truck as they may not be designed to handle such vibrations.
If you are concerned with the screws coming loose, a drop of locktite can go a long way in making sure it never happens to you again.
Stephen Swaffer:
--- Quote from: Brian Jojade on June 13, 2022, 12:27:20 PM ---Properly tightened screws in a proper panel shouldn't require regular tightening.
Now, if you're using a power distro panel that isn't designed for road use (ie, a homemade distro) then it's much more likely that things can shake loose in the truck as they may not be designed to handle such vibrations.
If you are concerned with the screws coming loose, a drop of locktite can go a long way in making sure it never happens to you again.
--- End quote ---
A couple of comments. Every lug/breaker etc. has a specific torque spec-hardly anyone actually uses a torque wrench/screwdriver-but if it's critical it would be a good idea. On connections that are run at/near/over full design load thermal expansion can loosen connections over time as can strands shifting. Keep in mind that a properly sized 75 deg C connection will run close to that temp when fully loaded-and each cycle tends to move material just a little more.
One of the most common issues found when I do infrared thermography predictive maintenance is loose screws-even on stationary equipment. I usually have no way of knowing if they were properly torqued to start with. Almost anytime I am working in a breaker panel I will quickly run through to check the tightness of screws-almost always there are a few loose screws usually on heavily loaded circuits.
I would think an off season double check would be best practice, if not essential.
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