Breakers Tripping on observing field

From AAS Observatory Wiki

Status: Re-opened

This problem was reported on the aas-members email list:

Bill T. (Sunday, May 4, 2008 12:22 PM):

Power also seemed to be a problem on the field. When I first got there, most (all?) of the fields were without power. Looking in the breaker box, 3 or 4 breakers were tripped. I found that if I plugged in my 24 volt power supply, the breaker would inevitably trip again. I ended up using 12 volt battery power (which results in slower slews with the NJP). We need to get someone to look into what is going on.

Harden S.:

Frequently, if a breaker has been tripped or otherwise cycled off and on many times, it gets to the point that even a slight current through it will trip it. This is probably the problem.

Greg T. (Monday, May 5, 2008 9:57 AM):

Sounds like it might be the breaker itself. If they are similar to the kind normally used in houses they can be easily replaced for about $4 each. Just turn off the main breaker, unplug the bad breaker, remove the hot wire from the breaker and replace with the new breaker. It's a 5 minute fix. Just remember to shut off the main breaker (and verify the power is off) before fooling around in there. Also, it's best to use the same brand breaker as the panel (GE, Square-D, etc.)

Jim H. (Monday, May 5, 2008 11:24 AM):

Those breakers are probably GFCI type, and they must be GFCI if they are powering outdoor or wet location outlets. GFCI breakers are more like $30++ and are a bit more involved to install. There is also a test procedure beyond the little "test" button on the breaker to confirm safe operation.

Using breakers as switches shortens their life significantly.

Club members plugging into field outlets that are not on properly installed GFCI circuits may shorten their life too.

The tester is cheaper than the GFCI breaker... :[http://www.gilchrist-electric.com/gfcireceptacletester.php]

If LCRA can replace breakers for us that may be the safest and smartest way to get it done, although certainly not the easiest or quickest way. I don't like having to think of things from a liability standpoint, but sometimes...

Action items for stleary

• Inspect breakers, plug in some devices on the outdoor tables on my next visit. (update - decided it was better to let LCRA do this)
• Contact LCRA to determine if there is a preferred procedure for electrical problems.

Note: emailed LCRA on May 5, 2008, response received

Please hold off on making any electrical repairs. I have forwarded this to our electrical repair staff for their review. For safety/liability reasons, I would prefer they deal with these repairs. I'll find out when they can be available to assess the repairs. If it can not be done fairly quickly, we'll look at an outside vendor. Keep me posted......

Sean Leary, May 9, 2008

There is an electrical outlet lying on the ground at the vehicle entrance to the UFO field (circular observing field extension, south of the observatory). Don't know whether the outlet is live. The concern is that it could be driven over, or immersed in water. (Forwarded to LCRA by stleary)

Skip Orrell, May 12, 2008

Safety alert - we are still having electrical problems on the field. At times, the table CBs are popping like popcorn. Mark lehman was especially having trouble at the table south of the path closest to the observatory. And all he was trying to use was a laptop computer. With the damp ground on Sat night, it seemed quite dangerous. This situation needs to get repaired! Be careful out there, y'all.

(Forwarded to LCRA by stleary May 12, 2008)

LCRA response, May 12, 2008

Our electricians are scheduled to be on-site for these repairs today.....I explained the other electrical issue to them regarding the UFO field.....hopefully they can repair that one also.

LCRA follow up, May 13, 2008

We repaired the electrical issues at the observatory and labeled outlets on the tables to proper GFCI breakers. They all checked out ok. We installed new capacitors for the water well.

Sean Leary, public viewing report, May 31, 2008

4 field breakers were tripped on arrival, and 2 other were tripped on 2 separate occasions by the AAS people on the field (breakers 6 and 14). No one seemed to be making excessive demands on power when the trips occurred, and no faulty or unusual equipment was seen. One of the UFO field tables may have an infestation of ants - could not confirm.

(Re-opened with LCRA June 1, 2008)

Bill Tschumy, email June 1, 2008

In addition, there were still power problems on the field. Whenever I plugged in my 24V power supply, the breaker would trip. This occurred even though the supply was not hooked to a scope (although it was on). I gave up and ran off of battery, but the breaker still tripped several more times through the night due to other's equipment. I know LCRA has "fixed" this, but I think we need them to do a bit more fixing ASAP.

Jack Estes, email June 1, 2008

Bill is right about the circuit breakers, the problem is still not fixed. I went over three times and reset one particular tripped circuit breaker. The right bottom breaker kept tripping with very little load on it.

Mark Florian, email June 1, 2008

If the circuit breakers are tripping even with a light load, and assuming they are not at fault, then it might indicate that a current is already flowing, thus raising the threshold level. This could be easily detected with an ammeter. One possible source would be ants, termites, grass, wet/damp/dry dirt inside one of the outlet boxes in the field, causing a leakage current to flow. (Someone should create a 12-step program for ants on electricity) . It would only take one box on a branch circuit of several to cause problems.

Mickey McInnis, email June 2, 2008

These may well be GFCI breakers. See if they have a "Test" button. If so, there might be some current leakage to ground, "pre-stressing" the GFCI circuit and causing it to trip easily. In an outdoor location, this isn't that unlikely. There's also the possibility that someone has some equipment that has a small ground fault. It might not trip on a regular breaker, but causes problems on a GFCI circuit. The current leakage required to trip a GFCI is a few milliamps. It's very easy to get enough leakage to mess them up, especially if you have a lot of wiring and a lot of fixtures.

Tim Brown, email June 2, 2008

Bill’s mention of a 24v power supply caught my attention. I was experimenting with an old Unitron 24V power supply and computer. My power supply burned up and I’m afraid shorted the circuitry in the computer. No breaker was thrown (unfortunately).

Mickey McInnis, email June 2, 2008

Mark, I read Tim's post to imply that the power supply was the source of the problem, not that a surge or some other problem on the 115 V site power.

Kelley Knight, email June 2, 2008

We had our Celestron plugged in and it kept rebooting itself as if power was interrupted on it. Lee and I plan to try it out at home this week to make sure it is not us and our lack of experience using it. The path lights that use to ring both fields, those were on a different circuit than the power for the tables or the observatory. Also, the electricity in the shed and the observatory does not go off.

Sean Leary, June 7, 2008

I met the LCRA electrician at the observatory on Friday, June 6. Borrowed a 24v power supply from Bill Tschummy, but they were unable to cause the breakers to trip when they installed it on a table. A few minutes later, several UFO field breakers did trip, when I turned on the computer in the observatory (the power to the monitor itself was not interrupted). The electrician was at the breaker box at the time, and he was able to isolate the problem to the monitor. After resetting the breakers, they used a heavy duty drill to test the field tables, and were not able to trip the breakers. Then they traced and tested the lines and did not find any problems. They labeled each table socket with the associated breaker. Each breaker controls about 6 tables; they said there are 3 breakers that handle the entire UFO field. I left a note on the North desk not to use the computer monitor. The electrician put forward a possible explanation, that the monitor was in some way introducing a change to circuits controlled by the field breakers, which caused them to trip. I was not really able to follow exactly how this might occur; it may have had something to do with how the wiring was set up and a shared neutral line.

Mickey McInnis, email June 7, 2008

That description worries me a lot. It sounds to me like there has to be something seriously wrong for this to be happening. The first thing that comes to mind to me is that there is a bad connection in some of the ground or neutral wiring on the electrical system at the observatory. I'm guessing that the monitor is leaking current to its ground wire and that is somehow finding its ground by going out to the wiring in the field. This current then trips the GFCI breakers on the panel. The incoming neutral and ground wire, and the individual circuit neutral and ground wires need to be very well bonded together. GFCI breakers have a little pigtail wire that has to be manually wired back to the neutral bus on the breaker panel. This sounds to me like the pigtails on the breakers that trip may not be grounded well. One way for this to happen would be if the pigtails were run together to a wire nut and then a single wire was run from the wire nut to neutral on the box. Another explanation would be if there is a bad connection between multiple grounding busses in the box. There might be some sort of problem if the earth grounding wire at the breaker panel is poorly connected, or if the ground rod itself isn't working well. The reason I say this is that, if things are wired correctly, nothing you can do to one circuit can affect the other circuits. Any leakage currents should trip that one breaker or flow harmlessly into the neutral/ground lead on the box. There should be no current flowing through the other breakers. In order to trip the other breakers, current has to be flowing through the breaker out into the field wiring. The doesn't make sense unless there's a ground problem.

Mickey McInnis, email June 7, 2008

Even if there is something seriously wrong with the monitor. Even if removing the monitor fixes the problem. Something's not right with the wiring. There's no way a device on one circuit should trigger other circuit breakers unless there's a wiring problem. If you tried to design a device to cause this problem, you couldn't trip a breaker on another circuit by plugging the device into another circuit. It may be a good idea to keep the old monitor around in order to try to figure out the problem. Perhaps put it in the shed with a label to not use it.

Mark Florian, email June 7, 2008

That's why I remain skeptical. Something is fubar with the wiring/ground( s)/installation if a monitor with say a flaky/noisy power supply can cause multiple breakers to trip, even if they are GFCI breakers. Perhaps there is a poor ground on the monitor circuit and it's now looking for a better one and it's pulling current out of some other branch or branch(s)? It is a possibility that if multiple wires were tied together using a wire nut, that one of them could have been torque'd off, thus causing a faulty circuit. I've seen it happen before. A DVM would be your friend here. So would a wiring/box inspection. . . .

Brian Banicki, email June 7, 2008

So, the monitor might be putting current on the (neutral wire and or Ground wire) and that goes to the neutral bar Ground bar and to ( naturally to ground) and trip that only breaker, but goes to other circuits tied to the neutral bar and tipping ( a few or all the breakers), so could we have a faulty earth ground and/or faulty neutral line tieing back to the power company.

Bill Tschumy, email June 8, 2008

I was the first to arrive and maybe 3 were already tripped. I reset them but had no trouble during the night. My 24V power supply didn't cause trouble this time...(The monitor)was turned off but plugged in. I went ahead and unplugged it because the previous weekend, when I had the problems, I don't believe it was turned on. The observatory wasn't open at the time although I suppose it could have been left on from a previous session.

Sean Leary COE log June 27, 2008

I replaced the defective monitor with a 15" LCD donated to COE, which seems to work well. I disconnected the old monitor, reset all of the breakers, installed the new monitor and powered up the computer. All seemed OK, but at the end of the evening I checked the breakers and number 14 had tripped. No one had used any of the tables during the evening. I would have to say that there may still be a problem with the observatory wiring.

Sean Leary July 10, 2008

Last Saturday during the members only star party there were 3 or 4 observers on differnt tables in the UFO field. Before sunset, I powered down the computer and LCD monitor and turned off the power strip where they were plugged in. Nonetheless, breakers 12 and 14 tripped several times during the evening. Informed LCRA that there is still a problem on the UFO field.

Sean Leary Aug 7, 2008

The AAS membership was getting tired of these 'breaker tripped' emails, so from this point on updates will only be recorded in this wiki.

Emailed LCRA Aug 7, 2008:

"Just a note to let you know that we are still experiencing tripped breakers on the observatory field. We have removed the 21" CRT monitor and replaced it with a 15" LCD monitor, but the problem still occurs. The problematic breakers appear to be 4, 6, 12, and 14. Unfortunately I have not yet found a way to reliably recreate the problem, but when I do, I will let you know."

Response from LCRA Aug 18, 2008:

The electricians have been informed of the ongoing problems and LCRA will let us know when more information is available.

Update on investigation 30 Aug, 2008:

I also spent 2 hours setting up and testing the field tables with several 100 watt table lamps, a radio and a large fan. Each test lasted 10 minutes, after which I checked for tripped breakers. I could not get the breakers to trip, I tried putting all devices on the same table, all devices on a single breaker, and various combinations of devices, tables and breakers. Eventually I attached at least one device to every table on the field. So the suggestion of attaching household devices to recreate the breaker problem has not worked. I am open to other suggestions.

Update for Sept 22, 2008:

LCRA asked me if other operators were tripping or closing the switches when they left at the end of the evening. I got these responses -

The only thing I touch is the power strip for the PC i turn it off on the power strip after the PC shuts down and of course I check the harlin smith drive switch and make sure its turned off nothing else. I do not touch any circuit breakers.

I have not played with the breakers in probably a year or so. I'm certainly not doing anything different from what I've been doing for years.

Meet with LCRA at COE on Nov 20, 2008

Electricians will continue trying to identify the problem, and will in the meanwhile install ground fault sockets on selected tables, also replacing the associated breakers with non-fault style.

Update Jan 4, 2008

For the past few weeks at most 1 breaker has been found tripped on Friday evening. Usually 14, it was once 12, and one week none were tripped. Possibly due to the cold weather?

Update Jan 28, 2009

About 2 weeks ago LCRA replaced the GFCI breakers with an individual GFCI receptacle on each table. They think this will resolve the problems we have seen. To reset a receptacle, just press the reset button which is integrated into the table socket outlet.