I would like to replace all the wires in my machine. I've got an old Astoria lever so the wires are pretty simple but I need to replace a few. For some reason a couple of them are really really thin (probably 16 AWG feeding the heating elements!)... So I replaced a few wires and I went up in diameter to 10AWG.

My question is this, where do you buy your fire retardant wires? I only need 20 feet in total, mixed colors, all 10 AWG for the element and 12 AWG for the water fill. Where should I get them? What's your secret Home-Barista source?

Because everyone loves photos, here they are:


These are the wires I replaced. They are nice and thick now. They represent two legs of wires feeding into my over-temp shutoff, then feeding into my elements as parallel loops.


This is what I replaced. These black wires were probably 16AWG with around 7 Amps running through them. Technically that's within the 80% engineered capacity for a 16AWG wire but not when they look like this! The wires were actually SMOKING HOT when I shut the machine off to do some diagnostics.

I got thick Teflon coated wire at Home Depot where you can cut to length. It's available in colors so you can indicate hot, neutral and ground.

Another option for colors is to find colored heat shrink tubing and either use it on the entire length or just an inch worth at each wires end. The good part is you likely can still add it to your existing wiring since generally the tubing will fit over the terminals you've already crimped on.
Something like this might serve you well.

http://www.amazon.com/Vktech-280Pcs-Shr ... ink+tubing

I wonder if McMaster-Carr sells wiring? If not, maybe a few phone calls to your local electrician who deals with appliances or industrial applications might find you a source of high heat wiring.

Find someone local to you who supplies Hotwatt high temp cable for ovens etc.
http://www.hotwatt.com/hightemp.htm

Could also try silicon coated wires and slip these inside high-temp fabric sleeve (http://www.firesleeveandtape.com/high-t ... ction.html).

Companies in the catering spares business usually carry these things.

The reason they were smoking hot is the crimped connection has corroded internally into a very high resistance connection. I can see this corrosion in your photo and it is confirmed by the location of the hot spot. The high localized IR drop results in excessive heat at the crimp. Every crimp connection should also be soldered and insulated with heat shrink tubing. Yo have to pull the colored sleeves off of the crimp connector to do this though. Commercial appliances are not constructed with a lifetime service life in mind so this type of failure is common unfortunately. The 16 gauge stranded THHN wire available at the big box is quite adequate for this application and available in colors. You could use 14 gauge stranded THHN wire which would completely fill the blue crimp terminals and provide a better mechanical connection but they also should be soldered as well. The THHN is rated for 90C temperature in dry locations. Inside of that machine is considered a dry location and 75C for wet locations.

OldNuc wrote:The reason they were smoking hot is the crimped connection has corroded internally into a very high resistance connection. I can see this corrosion in your photo and it is confirmed by the location of the hot spot. The high localized IR drop results in excessive heat at the crimp. Every crimp connection should also be soldered and insulated with heat shrink tubing.

+1 for this thought!!

OldNuc wrote:Every crimp connection should also be soldered and insulated with heat shrink tubing.

It should be fine to do that here, but in general you want to be very careful about soldering crimp connections where they might be subject to vibration or movement, because the soldered joint produces a stress riser where the wire exits the connector. A proper crimp produces a cold weld that is gas-tight, but most tools will not produce a proper crimp. In a moist environment Stabilant is useful to keep moisture out and provide the equivalent of a soldered joint without the stress riser. I have successfully used it in similar connections in motorcycles, and the results have been good for many years.

Best,
David

You are correct as a proper gas tight crimp can not be made with the common hand tool crimper that costs $10.0 or so. You only solder on the end away from the insulation and use a high power gun, there will be no wicking back out the end into the wire. I have been soldering these since the 60s and the USN sub service with no documented failures. Stabilant is a bit pricey when compared to solder but it would work fine. Pays your money and take your choice.

I've run into this on the motorcycle charging systems I work on which have factory crimp connections. The crimp connection builds up corrosion/resistance from the repeated heating/cooling cycles & can melt down the plastic connector they are mounted in. Cleaning & soldering or completely replacing the connection with a new soldered crimp connection solves the problem permanently.

I've had no issues with soldered wires breaking but it's always a good idea to add a 1" piece of heat shrink tubing to reinforce the area & protect the soldered/crimp area.

When I taught soldering at ET-A school the idea was to preheat the gun tip, apply solder, shake off molten ball onto floor, apply tip to the cut end of the wire sticking through the connector and add solder and as soon as it liquefied withdraw solder and gun. These were 260 watt Weller soldering guns. The solder never gets past the crimp which gets around the wire breakages issue. We graded labs on no wicking past crimp by opening the example up and looking. There was no heat shrink so there was a tight fitting sleeve that was slid over the wire and crimped sleeve. I have used this technique on old Harley MCs and it is near indestructible.

The high tech Stabilant would be easier to do if not having experience and tools to be able to do this soldering as the cost of these soldering gun is close to the cost of the Stabilant.