My plugs are melting

[JChenault]

I do a lot of work in a venue that has 'well used' equipment. We have two styles of EDI dimmer racks. One that uses pin plugs, and one that used edison. We plug our circuits directly into the dimmers.

Tonight I was setting up our next show, and discovered not one but two melted male connectors. One a pin plug, one an edison plug. The pin plug seems to have fused itself to the female in the panel, and then generated enough heat to destroy the plastic of the male pin plug. The edison plug had gotten hot enough to melt the plastic holding the male blade in place ( leaving a nice round hole).

This is the first time in over 30 shows in this facility that I have ever had a plug fail in this way. Two in one show makes me think there may be something systemic going on.

The pin plug had 1250 watts plugged into it. I am not sure what the Edison had, but the max possible would have been 1500.

Any ideas what could be going on to cause this rash of failures - and what I might be able to do about it to fix it?

Thanks in advance.

[MNicolai]

I'd say the area the cables were all plugged into was not vented as well as it should have been, and if the ambient temperature from the dimmers and the cables was enough to cause just a single connector to fail, it would be enough to cause any or all of them to fail. If ambient heat is the culprit, I'd actually be surprised only two connectors fell victim.

I'm not familiar EDI racks, but if there's a fan that's supposed to be cooling the racks down, you may want to check that it's still operational. Otherwise if it was a 'freak accident,' in the future be more careful about ventilation where all of the connectors are patched in.

[venuetech]

The screws on pin plugs pins may back out with repeated load cycles.
once it starts backing out bit by bit, heat is generated by the loose connection aggravating the problem.
with the end result that you have in hand.
the problem may have started with a high load on the connector years ago. I suspect that the screw was not torqued properly when the plug was installed.
if you have a circuit that is intermittent in operation it is likely a plug problem. Run a load on the cable and feel each plug for a warm or hot connector
If you catch the problem early all you need do it to tighten the screw.

[derekleffew]

venuetech has the right idea, and MNicolai's theory is frankly, horse hockey.

I suspect you'll find, JChenault, that the problem originated with the hot pin of each connector.


http://www.facebook.com/#!/photo.php...d=750209362528

[ajb]

Your male stage pin plugs need to have their pins split and cleaned, and you need to replace your edison receptacles. It could be an issue with the contact screws, but more likely the plugs are not getting good contact with the receptacles due to wear and/or surface dirt/corrosion. Fortunately Stage Pin plugs are designed to compensate for wear (by splitting pins) and are easy to clean. The edisons have no such wear compensation, and will simply need to be replaced.

The symptoms you've described can originate with the hot or the neutral contact.

[millamber]

What type of EDI pack is it? Is it possible that it is a 1.2kw pack and not a 2.4kw one? The loads stated on a 1200w pack, provided the breaker didn't trip, would be an overload on the system and could cause the problems you are describing.

[JD]

Still, a Stage Pin connector (at least the ones EDI uses) are 20 amps and would not melt. The "well used" is the clue. As said above, pin connectors need to have a little PM from time to time, and all connectors need to be clean. Although Edisons are pretty reliable, the fork in the female end can lose tension just as the male stage pin connector can. If either is loose or corroded, then your effective contact area plummets de-rating the connector. The other big area is loose screws in the connector as said above. Every plug and receptacle has two areas of connection that are equally important; Cable to plug, and plug contacts. When you plug a plug into a receptacle you now have three points of contact that can cause problems; Cable wires, connector contact area, and wiring to the receptacle.

[Woodj32177]

I agree the stagepin probably just needed to be split,
usually that is the cause of Stagepin failure.

As for Edison, Usually the cause is a loose screw inside the connector.
Although I only buy hubbell connectors, so I could see a cheaper connector having issues with the contacts burning out from repeated use.

Joshua Wood

[Tracyu]

I do a lot of work in a venue that has 'well used' equipment. We have two styles of EDI dimmer racks. One that uses pin plugs, and one that used edison. We plug our circuits directly into the dimmers.

Tonight I was setting up our next show, and discovered not one but two melted male connectors. One a pin plug, one an edison plug. The pin plug seems to have fused itself to the female in the panel, and then generated enough heat to destroy the plastic of the male pin plug. The edison plug had gotten hot enough to melt the plastic holding the male blade in place ( leaving a nice round hole).

This is the first time in over 30 shows in this facility that I have ever had a plug fail in this way. Two in one show makes me think there may be something systemic going on.

The pin plug had 1250 watts plugged into it. I am not sure what the Edison had, but the max possible would have been 1500.

Any ideas what could be going on to cause this rash of failures - and what I might be able to do about it to fix it?

Thanks in advance.

Most likely bad plugs but here's some other things to look at.
If these are EDI SPP or DIMMEX packs you should also check the wiring to the receptacles. Kill the mains power and remove the covers. If this is something like the SPP 2X2 Pro those modules mating pins can also get pinched. Make sure the fans are working. There's a lot of heat sink in those units so at low wattage they can run a long time before you get a thermal cut out.
Good luck with it!
Tracy

[JChenault]

To answer some questions.

On the Edison - the heat build up was definitely in the male plug. The screw was not noticeably loose however. Could be long term oxidation.

As to the stage pin - I would not be surprised if it was arcing between the male and female pair.

I am quite willing to blame this on age and random factors aligning to make everything go at once - but was wondering if there was a more general systematic reason that someone might think of.

On the other hand, today I had two scrollers fail. One because a drive belt broke. The other because the end of the gel string detached itself from the spindle.

Perhaps I need to go read my horoscope. or stay in bed.