Olympia Express Club wiring lessons learned

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
jwCrema
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#1: Post by jwCrema »

I've done two posts regarding repairing the wiring of an Olympia Club.
Restoring a sweet 1974 Olympia Express Club
Club 110V conversion

The Club has a 1350W element - which is a decent load.

Both efforts are fine for the neutral side of the circuit - both are not correct for the hot side. The common misstep is the temperature spec is too low - things are melted or brittle. I'm going with a temp spec of 200C or better on this try. The original Club wiring has some plastic insulators on the spade connectors; over time they get brittle and acquire a burnt petina.

I'd seen silicone wire used in this forum, so I used this: https://www.amazon.com/gp/product/B089CRKSNN in the 2022 effort. It does not work on the hot side of the circuit. The insulation is brittle and must be replaced after 90 days of use. Ira mentioned that he uses an insulated high temp wire https://www.amazon.com/gp/product/B00PZO6XI4/ - I'm going to use it on this go. The wire used in 2018 is still excellent and Amazon has small lengths for sale.

I used the wrong female spade connectors on the hot side in both repairs. This is what "wrong" looks like:




I am going to a bare nickel connector, rated to 900F.


Heat shrink has a lovely appearance, but the material I have found are marginal on temp spec for the hot side of the circuit. I am thinking about a PTFE insulator rated to 500F to reduce the exposure of bare metal.

All connections were crimped with a Ancor 701030 Double Crimp Tool (in 2018 I paid $62.10, now this baby is over $100!). They are worth having in the tool chest.

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Jake_G
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#2: Post by Jake_G »

jwCrema wrote:Both efforts are fine for the neutral side of the circuit - both are not correct for the hot side.
Hey Jack,

It has been quite a while since my electrical fundamentals courses at university, so I'm hoping you or someone else can enlighten me as to why the neutral and hot sides of the switch would have any difference whatsoever.

Circuits being, well, circuits and all, means that any current flowing through the hot terminals must be flowing through the load and back through the neutral terminals just the same. The only exception would be if you have a ground fault and some of the current is flowing through the machine case back to the wall, or through the user (bad deal).

It seems to me the more likely scenario is that the male terminal on the switch had done oxidation or the female terminal had a loose fit. Whatever the root cause, the thing that causes heat in an electrical junction is a combination of the current and the voltage drop (Power = Voltage drop • Current). Sonce wave established that the current through the neutral is the same as through the hot, the difference must be the voltage drop across the connector, which is measured as resistance...

NB, I don't think the wire is at fault. I think you have poor connections at the points where the charring occured.
Maybe I'm missing your point?

Cheers!

- Jake
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DefaultIT
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#3: Post by DefaultIT »

Well hmm. I have a couple of the old style white plastic covers that have gotten brown/brittle/broken off that I was going to re-terminate with new spades and the clear boots to cover them, but upon closer look, I guess these boots aren't silicone (as I had thought) but PVC and rated to 257º F

I had assumed it was just the boiler heat that was cooking these things and not line resistance...kinda seems a little underspec'ed if they're getting that warm under load.

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Jake_G
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#4: Post by Jake_G »

It's all about having good contact.

If there is no voltage drop across the connection, there is no power dissipation and no extra heat. If you have several connectors in the same vicinity of a heat source (the boiler) and only some of them are discolored, you must ask yourself why this one is baked and that one looks ok.
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jwCrema (original poster)
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#5: Post by jwCrema (original poster) »

Jake_G wrote:Hey Jack,

It has been quite a while since my electrical fundamentals courses at university, so I'm hoping you or someone else can enlighten me as to why the neutral and hot sides of the switch would have any difference whatsoever.

...
Maybe I'm missing your point?

Cheers!

- Jake
Hi Jake,
All connections were done with that spiffy crimp tool and are tight and clean.

I will take some pictures and annotate the wiring diagram with crispy, not crispy. I have a preliminary answer to explain why the temperature difference, but I am asking friends for review and comment before I post.

My point is simple: the temp spec on every component in an espresso machine wiring harness matters. I think 230C is high enough, but some calcs I've done say, maybe not on a 1350W machine. I owned a highly regarded pump machine before I went antique lever; after a year the wiring insulation was so brittle it was scary.

All of my new wire, connectors and insulation arrived today. I will take pics of the new wiring this weekend.

I really appreciate your taking the time to respond!

ira
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#6: Post by ira »

I always find it surprising how often little consideration is given to the long term environment that wire, plastic and electronics operate in. I see it mostly in old industries that are forced to move to electronics without understanding what that entails to do it properly. It might also have to do with suppliers who given a usage, said this will work. Higher temperature wire is more expensive, sometimes a lot more expensive, and in the case of braid covered silicon, the stuff I use when repairing espresso machines, it's expensive and needs to be kept away from edges or encased in some sort of protective sleeving as its cut resistance is not that high.

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Jake_G
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#7: Post by Jake_G »

jwCrema wrote:All connections were done with that spiffy crimp tool and are tight and clean.
I was thinking the likely spot for poor contact is between the connector and the device, not the crimp to the wire.

I understand the critical look at heat ratings of electrical devices trapped in a poorly vented box with a heat source, but I still don't understand why the phase lead would be subject to higher temperatures than the neutral.

Any further thoughts on this?
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ira
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#8: Post by ira »

They all carry the same current, it's usually the one that's loose or dirty or has a bad crimp or got wet or the wire was under tension.

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Jake_G
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#9: Post by Jake_G »

Exactly.

That's why I'm questioning specifications or temperature ratings being the root cause. There must be an underlying condition causing a voltage drop at the affected area that then opportunistically exploits any potential underrated components. If there is not issue at the connections, there should be no issue with the components.

Likewise, over-speccing the components would only delay the inevitable if the underlying conditions are still present.
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#10: Post by DefaultIT »

ira wrote:They all carry the same current, it's usually the one that's loose or dirty or has a bad crimp or got wet or the wire was under tension.
Call it overcautious or under-confidence in my crimping abilities but I almost always solder crimp-on connectors to be safe. If it's a spade that's been on and off a few times, I will sometimes squish the sides back down (with linesman pliers) to ensure there's enough clamping force for them to 'wipe' a new gas-tight connection when they go back on. I've also been fairly recently turned onto CRC contact cleaner and have been having pretty good luck with that.

As for boots, I've decided on a slightly annoying but hopefully permanent solution for my machine: silicone tubing. I had some left over from some breath controller tinkering (had to check the order: 3mm ID/5mm OD):


Silicone left, PVC right...which, based on how thoroughly my shrink tube-covered connectors disintegrated, likely wouldn't last near the boiler

It takes some wiggling, but I can stretch it over standard (large) spades, which should do a bit better than the standard white plastic guards at keeping moisture out (if you have a vacuum breaker valve as...enthusiastic...as mine, this will appeal to you). So my new ones are going like this:

• Cut, strip, and tin wire end
• Slip roughly 3/4" silicone tube over wire (always forget to do this first)
• Crimp on spade connector
• Flow the solder inside with iron
• Work the tubing over the spade end
• Hopefully never have to do that again.

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