Fried Boiler Wire

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Fried Boiler Wire

Post by chas » Mon Jul 07, 2008 8:36 am

OK I got it fixed with the parts I had lying around the house. I added a photo of the fried wire, below. The melted black plastic cap that was responsible for the stench.

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I came downstairs this morning and smelled a smell like burned synthetic carpet. I sniffed all over the house and couldn't find it. But then while pulling the second espresso of the morning I realized the smell was coming out from the vent holes in the cup warming tray. A quick check revealed that the steam boiler power wire's insulation is all bubbled up and melty looking for about 1 1/2" from the crimped spade lug connector. No doubt the crimp loosened up forming a high resistance connection and now gets really hot.

I have the same problem with the auxiliary high power heat coils in my heat pump so I have a whole set of crimp connectors and extra heavy duty wire handy. I am hoping I can fix it myself when things cool down.
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Fried Boiler Wire
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Re: Fried Boiler Wire

Post by JohnB » Mon Jul 07, 2008 12:13 pm

I see this issue on motorcycles in the rectifier connectors. Resistence builds up in the crimp from the repeated heating/cooling cycles. Cleaning & soldering the crimp so that the solder flows down inside the crimp solves the problem. When I have my V2 apart for the board upgrade I'll take a look at the connections & solder the crimps in high heat areas.
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Re: Fried Boiler Wire

Post by chas » Mon Jul 07, 2008 12:50 pm

Perhaps you're correct about the heating and cooling cycles. I didn't have this issue in 4 years with my S1 that I left on 24x7. But it happened with my VII after 18 months using the timer. However, there were at least 2-3 folks with the S1 that reported this issue after a length of time. I probably have just about the oldest VII out there, so we could be on the cusp of others starting to see this.

Your recommendation is good to check the connectors on the boilers whenever you have the covers off. You can easily pop those black plastic covers off the two steam boiler connections. The other connections don't have covers and are clearly visible.

The main power wire comes from the steam boiler triac to one side of a pressure switch. (An overpressure condition pops that switch and breaks the connection.) The other side of that switch has the short black 12 gauge stranded copper jumper wire that goes to the plus side of the steam boiler heater element. That's the wire that fried.

If I had followed my own advice and checked that a couple of weeks ago when I had the covers off to put in the new controller board, I probably could have avoided a repeat performance!
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Re: Fried Boiler Wire

Post by JohnB » Mon Jul 07, 2008 3:44 pm

I'm surprised we haven't seen more of this as the inside of a d/b espresso machine is a harsh environment for electrical connections. Between the heat from the 2 boilers & the moisture from the hot water tap/steam wand its almost as bad as Aprilia's brilliant idea of bolting an air cooled rectifier to the engine case directly behind the oil tank covered by a fairing.
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Re: Fried Boiler Wire

Post by Richard » Mon Jul 07, 2008 9:17 pm

chas wrote:The melted black plastic cap that was responsible for the stench.
Must be a holiday weekend epidemic. That photo is a dead ringer for the wire I replaced just this morning.
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Re: Fried Boiler Wire

Post by chas » Mon Jul 07, 2008 10:37 pm

One thing I noticed from the labels on the wire. It's 12 gauge rated at 105C. However, boiling water at 1.3bar is slightly hotter than that and the wire is right above the boiler and it direct metal to metal contact. That's pretty marginal operation!
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Re: Fried Boiler Wire

Post by chas » Tue Jul 08, 2008 10:19 am

Between the fact that using three crimp connections yesterday reduced my stock (I screwed the crimp on one) and the fact that the ones I have aren't shielded, I went on-line last night to find some insulated ones. Currently I have a piece of electrical tape around one terminal in my VII!

First, I came across a site that discussed the wonders of crimped connections versus soldered. The only caveat they had was in very moist environments where they said the moisture could get to the wire and corrode it resulting in pretty much what I saw. Their recommendation was to get crimp connectors that integrate a length of heat shrinkable tubing. I had never heard of these before but after that I looked and quickly found a source. As soon as they arrive I'll probably make a replacement cable and replace the one I did the other day with this solution and see how it works. Hopefully that will resolve both my insulation and moisture issues.
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Re: Fried Boiler Wire

Post by zoey » Tue Jul 08, 2008 11:06 am

I'm sorry that this has happened to you and thankful that it didn't progress to a fire!
On the other hand, your ill-fortune might, literally, save some lives.

You reminded me of a potential problem I found while repairing my machine a while ago.

See any potential issues with a hot boiler and wires in this photo?
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Re: Fried Boiler Wire

Post by JohnB » Tue Jul 08, 2008 11:23 am

You can buy heat shrink tubing at Napa, Radio Shack & online. The nicest male/female connectors I've seen for the solder phobes out there come from Wurth. These have a ring of solder inside the "crimp" area & a heat shrink tube over the outside. Insert the wire & heat the connector with a hot air gun until the solder melts into your wire & the tubing shrinks. Nothing beats a soldered joint for preventing corrosion & resistance build up.
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Re: Fried Boiler Wire

Post by jbb » Sat Apr 25, 2015 11:01 pm

Given that this thread is being resuscitated from 2008, it would appear there was not an epidemic of fried boiler wires. But I'm afraid I've come down with a case. This is on an original S1; I'm the second owner for several years now. Other than replacing the pump and periodic descaling it's run trouble free. But this morning there was a fried electronics smell during warm up. After steaming one pitcher, the boiler started making the "heating up sound" but could not come to temp. As you can see in the picture below, once I got inside one of the crimp connectors to the steam boiler heating element is clearly fried. The black plastic "boot" that I think is supposed to give the connection some protection is at this point now hard and brittle.
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This is the wire that comes off what I'm assuming is the overpressure circuit breaker, as in the picture below.
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The terminal itself has some corrosion, but I suspect after a steel wool rubbing there would be some amount of solid metal underneath.
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As seen in this picture, the other terminal may not be far behind.
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I guess I have two questions.

1) Is this likely to be a replacement part I could order from Chris?
2) What would the assessment be on the posts on the heater element itself? Clean it up as much as possible and go with it, or get a new heating element?

Thanks!

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Re: Fried Boiler Wire

Post by chas » Sat Apr 25, 2015 11:21 pm

It happened to me often enough that I went to the HW store and bought a small package of six crimp connectors and a couple feet of the right gauge of black wire, then I made a replacement jumper wire and a couple of spares.
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Re: Fried Boiler Wire

Post by jbb » Sun Apr 26, 2015 12:42 am

Thanks Chas. Do you have a feel for what the right gauge would be? I imagine it needs to be OK for high temp applications.

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Re: Fried Boiler Wire

Post by chas » Sun Apr 26, 2015 8:57 am

I think it's 14 gauge copper stranded though it might be printed on the side of the wire.
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Re: Fried Boiler Wire

Post by chas » Sun Apr 26, 2015 9:22 am

If you already have a soldering iron and some solder you might want to tin the stranded wire before you put the crimp connector on. The failure mode is that moisture gets in between the copper strands between the crimp and the wire's insulation over time and starts to oxidize the copper. That makes the copper heat up when the current is flowing until it eventually gets bad enough to fry.

Of course if you don't already have soldering equipment, then it's cheaper to buy a pack of connectors and wire, make your own, and just replace as needed.
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Re: Fried Boiler Wire

Post by jbb » Thu May 07, 2015 8:13 pm

Well, I finally got around to powering up the S1 again after replacing the fried disconnects on the steam boiler. As the existing wires leading to both terminals appeared largely intact, I cut off the defective disconnects along with a short segment of the wire and replaced them with the insulated 16-14 guage disconnects shown in the picture. I also cut off a brittle segment of one of the grounding wires and replaced the connection, tinning it with a little solder. While she was taken down I figured it was a good time for a thorough descale of both boilers, which is what took the longest.

After plugging her back in, unfortunately all is not well. When the steam boiler cycles on, or in some cases cycles off, there appears to be some some sort of power surge that pops the GFCI. Chas, if you or anybody else has some suggestions please let me know. Even after substantial cleaning, the heater terminal still shows a fair amount of pitting. I don't know if that would cause it. Or maybe the disconnects I used can't handle the load. Any ideas would be appreciated. Thanks.
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Re: Fried Boiler Wire

Post by chas » Thu May 07, 2015 9:07 pm

Unfortunately, after removing the lid and scraping out the old gasket so that you could descale the boiler, it sounds like you most likely need to replace the heater element, so you'll get to do those steps over again.

Most likely some condensation has gotten inside the tube that surrounds the actual electrical element. This allows a small amount of current to flow from the element to the tube which is grounded. This causes a very small differential current between neutral and ground which is what triggers the GFCI.

You might be able to do a check for this condition if you have an ohmmeter. To do this 1) unplug the machine. 2)Disconnect the leads from the heater element. 3)Ohm between one element lead and the top surface of the boiler. 4) Check between the other element lead and the top surface of the boiler.

Both readings should be infinity; i.e. open circuit. If you get any kind of high resistance reading from either measurement, the element is bad.
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Re: Fried Boiler Wire

Post by jbb » Thu May 07, 2015 10:01 pm

Thanks Chas. I do have an ohmmeter and I'll give it a try.

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Re: Fried Boiler Wire

Post by jbb » Thu May 07, 2015 10:58 pm

I tried the ohmmeter at several dial settings (since I didn't know if that mattered in this case) and the needle never flinched when I connected between either element lead and the boiler lid.

If there is some sort of grounding issue, is there any way that my less than ideal soldering job seen below could be responsible?

Thanks

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Re: Fried Boiler Wire

Post by jbb » Thu May 07, 2015 11:02 pm

trying the attachment again.
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Re: Fried Boiler Wire

Post by jbb » Sat May 09, 2015 6:33 pm

But turns out if I run it off a non-GFCI outlet both boilers cycle just fine. Go figure. From that can I conclude the electrode is actually OK and the problem lies somewhere else?

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Re: Fried Boiler Wire

Post by chas » Sat May 09, 2015 6:46 pm

Was this just for test purposes or do you have the machine located somewhere that you actually can permanently plug it into a Non-GFCI outlet?

It's possible that the leakage resistance was too low to measure with the ohmmeter. Can your meter also measure AC voltage? If so, with the power on and the boiler heating, measure the voltage between the boiler lid and the neutral (blue) wire to the heater element. This absolutely has to be 0V or else the GFCI will surely trip. If it is not 0V you probably are back to having to replace the heater element.
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Re: Fried Boiler Wire

Post by jbb » Sat May 09, 2015 7:18 pm

Thanks Chas. It reads both AC and DC, so I'll give it a try. No permanent connection to non-GFCI. Big orange extension cord running across the entertainment room. WAF very low in that configuration, so just for test (and to actually make coffee) purposes.

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Re: Fried Boiler Wire

Post by jbb » Thu May 14, 2015 2:00 am

I feel kind of stupid asking this, but I'm taking it you mean measure any voltage between the neutral wire and the boiler lid while the wire is still attached to the heating element, right?

If that's true, I'm getting a reading of about 8 volts when the element is on and 0 when its off.

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Re: Fried Boiler Wire

Post by chas » Thu May 14, 2015 9:55 am

That's plenty of voltage differential to trip a GFCI. I suspect it's the heater element in that case.

However, there is one other thing you can check. When facing the back of the machine with the covers off, there is a large bolt behind the controller box on the far left side. All the ground wires connect there. With the machine on, check for voltage between this bolt and the steam boiler housing. That should definitely be 0V. If not then you need to check the connection of your ground wires at the top of the boiler, something is not making a good contact.

For additional confirmation you might check between the group boiler neutral and the group boiler housing. This should also be 0V. If you see 8V here as well. You might want to stick the voltages probes directly into the GFCI's neutral and ground holes and ensure that you see 0V there.
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Re: Fried Boiler Wire

Post by jbb » Thu May 14, 2015 9:49 pm

Hi Chas
I'm attaching the results of the tests you suggested. Please me know if the pattern indicates anything one way or another. The machine was turned on for all readings plugged into a non-GFCI outlet. For the GFCI outlet I typically use to run the machine testing between neutral to ground with the meter showed 0 volts. Thanks for your help.
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Re: Fried Boiler Wire

Post by chas » Sat May 16, 2015 10:21 am

Hmm. I just printed this data out so I can stare at it for a while. The fact that you are also seeing voltage between neutral and the group boiler chassis when the group boiler is on and the steam boiler if Off has me scratching my head - especially since the GFCI is only triggering when the steam boiler comes on.

Of course the problem could be additive and the GFCI might only trip when both boilers are on at the same time? Have you ruled this out by switching the machine to 15A mode?
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Re: Fried Boiler Wire

Post by jbb » Sun May 17, 2015 12:58 am

Yeah--sort of a complicated set of readings. Sorry about that. Just started trying things to see if I could find a pattern. Reminds me somewhat of the exams my electrical engineering dorm mates had in college. Anyway, here's a funny thing. I plugged the machine back into the GFCI and tried to pay close attention to when it tripped. Usually it was just as the steam boiler cycled on. But sometimes it made it past that point, and, if it did, it tripped when the steam boiler cycled off. That got me thinking about the temperature probe-and my worry a couple posts back about my attempts to reground that connection being less than ideal. Figuring I had nothing to lose, I cut off the crimp, stripped off a good cm or so of the insulation and just wound the copper around the bolt before racheting it down. And believe it or not it now does not trip the GFCI. Left it on overnight to cycle back and forth and seems OK. If I can find a crimp with an opening big enough for the bolt to pass through I will go back and do a better job of it. With respect to what the voltage between neutral and both groups means-no idea-altering the temp probe ground did not change that for either boiler. She's been around the block a few times now and the wiring in general is starting to get brittle. I imagine we can all sympathize to some extent.

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Re: Fried Boiler Wire

Post by Futahaguro » Fri Apr 22, 2016 10:56 am

Tossing some heater element pictures in for reference since this thread commented on them.
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