Wednesday, November 10, 2010

Project Time

Green Wall Clock: Ready For Destruction

Today's title is a double-entendre: not only is this a time for doing projects, but also one of today's projects is, well, time. Which is to say, I set all the clocks, of which there are too many aboard Odyssey. In fact, there are no fewer than 15 clocks on the bus, and that does not count cell phones, watches, dive computers, and laptops.

Of course, like most everyone else, we need to change most of these clocks twice a year when Daylight Savings comes and goes. But we also routinely need to change almost all of them every time we cross a time zone boundary, which is an average of another eight times each year, for a whopping 150+ clock resets each year.

Having so many clocks means that whenever we change time zones or DST status, it's usually a day or two before I get to all of them, and today I knocked that item off the list. It's been on my mind since our cruise, where the fact that the US was still on DST while the rest of the world had already reverted to standard time meant we changed clocks four times on a seven day cruise, only to have to change yet again the day after we returned.

Most of the clocks are important in one way or another. For example, having the wrong time on the inverter control might mean the generator starting unexpectedly in the middle of the night, or during "quiet hours" someplace where it might matter. Having the wrong time on the engine data recorder would mean incorrect time stamps on fault codes. Yet few of these clocks are normally visible inside the bus, prompting some friends of ours to periodically remark that we have no clock, and to give us one as a gift. Since we also have no place to securely mount any other clocks, these end up kicking around the bus until they are lost or broken, at which point they give us another one, over my protests of having another mouth to feed, as it were.

For the curious (because I know someone will ask if I don't post it), these are some of the devices with clocks we have aboard:

  • Inverter (Xantrex/Trace SW4024)
  • Microwave (GE Advantium 120)
  • Coffee maker
  • Two programmable thermostats for heating and air conditioning
  • Engine data recorder (Silverleaf VMS-200)
  • Speedometer
  • Dash radio
  • Dashboard GPS
  • Two bedside alarm clocks
  • DirecTV receiver
  • Sony television
  • File Server
  • Two scooters
  • Portable GPS (used on the scooter or in rental cars)
Some of these don't really need to be set, per se, but only have the time zone changed. For example, the two GPS receivers always know what time it is, as does the DirecTV receiver. Some of the clocks I simply leave on Pacific Time continuously, as I do with the time setting on this blog and other web sites I frequent. But many of the clocks demand attention with every time change.

Speaking of changing clocks, one of my other projects today was replacing the power outlet for the coffee maker. Long-time readers may remember me saying that whenever we had a power glitch, such as the air compressor hard-starting while we are on a 15-amp service, that the clock on the old coffee maker would lose its mind and have to be power-cycled -- the darn thing would even quit in the middle of making a pot. That coffee maker was on its last legs and we replaced it a couple weeks ago with a different model.

Since then we've noticed that even the new one has had some clock-resets, and Louise finally traced it to a finicky receptacle. Moving the plug to the other socket on the same outlet improved things somewhat, but clearly there was a problem. Today I replaced the receptacle with a new one.

As long as I had the bad one in my hand, I decided to take it apart to do some failure analysis. What I found was that the U-shaped grip on the neutral side of one of the pair of outlets had fractured in two, and the plug was making minimal contact on only one surface with the half that remained, which could no longer "grip" the tang. It was clearly metal fatigue, but we generally don't unplug/plug the coffee maker in often -- perhaps we've done it a few dozen times in six years. It's possible the grip was scored by an off-angle plug insertion or removal at some point, and it is also possible that coach vibration contributed to the failure. Nevertheless, it's an early failure for this kind of thing, and it has prompted me to add a visual inspection of all receptacles aboard to my project list.

We have one more night here in Delray Beach before we head north, and I am hoping to get a few more items ticked off the list. If I can find the time...

Image by Alyssa L. Miller, used under a Creative Commons license.


  1. Sean
    Just a thought, you might try using hospital grade outlets. They are very durable and designed to take abuse. They can be identified by a green dot on the face. The dot means that they have a certified ground connection.

  2. Frank, at a cost premium of about 2,000%, I could replace each receptacle 20 times before I would approach the cost of changing to hospital-grade items. Incidentally there is also a "spec grade" which is somewhat less of a premium, around 1,000% or so, yet just as durable (the cost difference reflects the manufacturers' greater liability for hospital grade).

    BTW, the green dot simply means "hospital grade." NEMA standards for hospital-grade receptacles (and the NEC provisions that govern them, a scant two) do not establish any "certification" of the ground connection beyond that specified for standard NEMA 5- series devices. The standards for hospital grade instead relate principally to plug retention and the ability of the device to withstand frequent plug cycles.

    That might have helped in this case, no doubt, but in 30 years of electrical work I have only ever seen a failure like this (not related to abuse) a small handful of times, and that would include in RVs.

    These are Decora outlets, BTW, which are also very difficult (perhaps impossible?) to find in hospital grade.

    I expect this was an isolated failure, most likely related to either a manufacturing defect or some trauma to the part when it was installed. Still, I will be inspecting all the outlets as a precaution.

  3. Had to chuckle a bit...only an engineer would take a replaced outlet apart for "failure analysis"! Good thing you did though, the information is key!

  4. Sean

    I understand the cost difference, most of our house has hospital grade outlets, I was working at a hospital where a new suite was being constructed, the wrong color outlets were installed. When they were exchanged for the correct color the electricians were not allowed to reuse the removed ones and I was there.
    My biomedical contacts tell me that Hospital Grade plugs and outlets have to pass a pull test as to force required to separate them, they also must pass a ground contact resistance test, above a certain value and they fail. Also on the plugs the ground prong is slightly longer to ensure that it is the last to break contact when the plug is removed.



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