Thermocouple wire connector

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Narwhal

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I'm not even sure if this is thermocouple wire, but does anyone know what type of connector/splice/terminal this is and where I can find another or a suitable substitute? The wire is very thin and is foe an EGT gauge.

Just trying to make life easy for my mechanic and source some parts. He said he "might" have a replacement but wasn't sure.

Thanks.
 

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Maybe it’s a crimp spade connector?

molex.com might have photos to compare
 
A cheap ass mofo would get in there with a small screwdriver and a pair of needle nose pliers, pry the crimp open, re-insert and re-crimp. Save $0.20 in parts for only 45 minutes of labor.

And, yes, the yellow / red pair is likely from a thermocouple.
 
Crimped connectors on little wires are destined to fail. Posi Locks are far better connectors. Take them apart and put them back together as often as you like, they work the same every time with no wire loss. If you want to stay with crimp-ons? Go to Polar Wire and get some good heat shrink terminals and a pair of ratcheting crimpers. The heat shrink works like a strain relief and protects the crimp. Spend a little more and get some good wire strippers, too. Better parts and better tools make better repairs.

E55FE07B-3097-479F-834D-B546FC362138.jpeg https://www.posi-products.com/
 
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Narwhal said:
does anyone know what type of connector/splice/terminal this is
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As mentioned its a standard insulated splice connector. A butt splice can also be used but you may want to check with mechanic first as some prefer a different style connector due to the small thermocouple wire size.

texasclouds said:
If your mechanic doesn’t have a bin full of those…fly away
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Didn't realize shop inventory equated to mechanic skill set.
 
Just to be clear, if the wires are for a thermocouple (that appear to be the case here), you cannot simply use any regular electrical crimp connector. In order to maintain the correct calibration of the thermocouple probe and gauge, you have to use a proper connector, which must be of the same metal as the corresponding wire.
 
Jim Carpenter said:
you cannot simply use any regular electrical crimp connector.
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FYI: you'll find its up to the system mfg'r what connectors are acceptable. For example, JPI recommends standard butt splices in this scenario.
 
Stewartb said:
Crimped connectors on little wires are destined to fail. Posi Locks are far better connectors. Take them apart and put them back together as often as you like, they work the same every time with no wire loss. If you want to stay with crimp-ons? Go to Polar Wire and get some good heat shrink terminals and a pair of ratcheting crimpers. The heat shrink works like a strain relief and protects the crimp. Spend a little more and get some good wire strippers, too. Better parts and better tools make better repairs.

View attachment 102230 https://www.posi-products.com/
Click to expand...

Thanks for that pointer. I never used Posi Locks, but I am intrigued enough to give that a try.
 
Narwhal said:
I'm not even sure if this is thermocouple wire, but does anyone know what type of connector/splice/terminal this is and where I can find another or a suitable substitute? The wire is very thin and is foe an EGT gauge.

Just trying to make life easy for my mechanic and source some parts. He said he "might" have a replacement but wasn't sure.

Thanks.
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It is unlikely to be athermocouple connector. You can't use a crimp a generic connector a thermocouple wire unless both connectors are guranteed to be at the same temperarure. Inside an engine compartment that is not likely to be true.
 
That is K-type thermocouple wire. I would recommend TE Connectivity PIDG (faston) fasteners if you just gotta go with spades. But the barrels mentioned above are definitely my top pick
 
sarangan said:
It is unlikely to be athermocouple connector. You can't use a crimp a generic connector a thermocouple wire unless both connectors are guranteed to be at the same temperarure. Inside an engine compartment that is not likely to be true.
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Every CHT and EGT probe that Grand Rapids sells uses these connectors. Always worked fine for me and everyone else I know who used their engine monitors.
 
Narwhal said:
The wire is very thin
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Crimp connectors are for particular gauges of wire, so you’ll need to figure out the gauge number for your wire. Some connectors for example are intended for gauges 18 to 22, and you wouldn’t want to put a thinner 26 gauge wire in one of those.

Once the wire’s end is stripped, you can measure the wire diameter with calipers, or compare to known wires.
 
NoHeat said:
you wouldn’t want to put a thinner 26 gauge wire in one of those.
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FYI: There are tricks to using standard connectors with small wire (24-26 AWG). One was to strip 3x the amount of conductor and triple it up before inserting it into the connector before crimping. But the better way is to strip the wire 2x the length of the connector crimp barrel then fold back and wrap the conductor around the exterior of the wire insulation. Then insert the wrapped wire/insulation into the connector and crimp.
 
In a pinch, use a couple of PIDG ring terminals with #8 button head screws, washers, nuts. Use heat shrink over the connections and then wrap in fusible tape. Makesure these connections don't overlap, they need to be staggered.
 
Stewartb said:
Crimped connectors on little wires are destined to fail. Posi Locks are far better connectors. Take them apart and put them back together as often as you like, they work the same every time with no wire loss. ...
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Never heard of Posi-Locks. Intriguing. Also called Posi-Twist and Posi-Tap. I will give them a try. Thanks.
 
They all have different purposes but work the same way. Very good products.
 
Jim Carpenter said:
Just to be clear, if the wires are for a thermocouple (that appear to be the case here), you cannot simply use any regular electrical crimp connector. In order to maintain the correct calibration of the thermocouple probe and gauge, you have to use a proper connector, which must be of the same metal as the corresponding wire.
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Just to be clear, that's not true.
 
I'm no electrical engineer but my understanding of these thermocouples is they translate temperature into electrical current. All those wires do is carry electrons to the instrument. Pretty simple stuff.
 
donjohnston said:
Every CHT and EGT probe that Grand Rapids sells uses these connectors. Always worked fine for me and everyone else I know who used their engine monitors.
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Thermocouple operation is based on the junction voltage at the interface of two different metals. When you introduce a third metal (ie crimp) you will create an additional voltage on the line, unless both crimps are at exactly the same temperature, in which case they will cancel out. For that reason, thermocouple connectors are special connectors made from the same material as the thermocouple wire. That way the connector does not introduce an additional junction. These are polarized connectors. The direction does matter. Just because they work fine does not mean you are getting the correct reading. It will still read high when hot, and low when cold. That does not mean it is accurate.
 
My experience with thermocouple wire is the importance of direct contact of the mating wires. If you try to connect with any type of crimp connection other than the exact metals involved, it will alter the readout a bit. So a quick disconnect limits things. I do have a couple of those quick disconnects. I will get the part numbers in the next couple days.
 
sarangan said:
For that reason, thermocouple connectors are special connectors made from the same material as the thermocouple wire.
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ARTRR said:
If you try to connect with any type of crimp connection other than the exact metals involved, it will alter the readout a bit.
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So, if an OEM like JPI Instruments states you can use a "good quality butt splice" to extend their thermocouple wires you should not believe them and alter their recommendation?
 
ARTRR said:
My experience with thermocouple wire is the importance of direct contact of the mating wires. If you try to connect with any type of crimp connection other than the exact metals involved, it will alter the readout a bit. So a quick disconnect limits things. I do have a couple of those quick disconnects. I will get the part numbers in the next couple days.
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Omega is one of the experts in this field. They have a chart that will show the different types of thermocouple and which connector to use. Some aircraft instrument manufacturers use these connectors.
 

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ARTRR said:
Omega is one of the experts in this field.
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Fine. But the question is, if JPI who provides the FAA approval to install their products in aircraft recommends standard connectors you believe that is not appropriate or legal and you should should alter that recommendation?
 
The key, if JPI suggests using a butt splice ,that would be a permanent connection. But they are also “meaning a direct connection of metals. A butt splice, unless having an overlap of the wires , would not be the best connection. Omega provides this, and also offers a quick-disconnect feature. That particular connector I described in the attachment can be secured in an engine environment and also provide for troubleshooting.
 
ARTRR said:
The key, if JPI suggests using a butt splice ,that would be a permanent connection. But they are also “meaning a direct connection of metals. A butt splice, unless having an overlap of the wires , would not be the best connection. Omega provides this, and also offers a quick-disconnect feature. That particular connector I described in the attachment can be secured in an engine environment and also provide for troubleshooting.
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This particular connector is also used by one of JPI’s competitors.
 
Heat applied to dissimilar metal connections generates a voltage when subject to heat. That's not only physics, but it's the principle that a thermocouple is based on. But that said, the difference may be so minor that it doesn't matter at all, and if you connect both wires the same way, and if the splices are at the same temperature, the voltages will cancel each other out anyway.
 
ARTRR said:
he key, if JPI suggests using a butt splice
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The key, as you mention, is that they do. And given electrical connectors are considered standard parts, technically they maybe substituted as a minor alteration per Part 43.
ARTRR said:
This particular connector is also used by one of JPI’s competitors.
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And another key. As noted in Post 9 it is up to the OEM what connectors are used.
Albany Tom said:
But that said, the difference may be so minor that it doesn't matter at all, and if you connect both wires the same way, and if the splices are at the same temperature, the voltages will cancel each other out anyway.
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Do you work for JPI tech support by any chance? Seems what you say is familiar along with a few others.;)
 
Exactly! That’s why I am stressing the direct connection of the wires. The Omegaconnectors does just that providing the thermocouple wires are matched to the connector.
 
Bell206 said:
Do you work for JPI tech support by any chance? Seems what you say is familiar along with a few others.;)
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Nope! I just provided a comment based on basic physics and common sense. Everybody on here already knows that the correct answer is probably whatever it says in the installation instructions of the manufacturer of the certified part.
 
Bell206 said:
So, if an OEM like JPI Instruments states you can use a "good quality butt splice" to extend their thermocouple wires you should not believe them and alter their recommendation?
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If both ends of the wires are in physical contact in a buttsplice, then it is fine. This is what JPI tells you to do. It even goes on to say that you should expand the hole to ensure that the two wires will mesh together. https://www.jpinstruments.com/FAQ/can-you-splice-the-thermocouple-probe-wires/
The discussion here was about crimped connectors, which does not normally mesh the two lead wires together. The current has to flow through the crimp metal, which will introduce another junction.
 
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So out of curiosity, how much of a variation are we talking about by using the "wrong" connectors? 3 degrees? 30 degrees? 130 degrees?
 
donjohnston said:
So out of curiosity, how much of a variation are we talking about by using the "wrong" connectors? 3 degrees? 30 degrees? 130 degrees?
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It depends on the temperature difference between the two connectors. If near a hot exhaust pipe, one connector could be much hotter than the other, resulting in that same difference being added/subtracted from the temperature you are actually trying to measure. If it is in a more protected area, probably not much difference.
 
sarangan said:
It depends on the temperature difference between the two connectors. If near a hot exhaust pipe, one connector could be much hotter than the other, resulting in that same difference being added/subtracted from the temperature you are actually trying to measure. If it is in a more protected area, probably not much difference.
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Could you tape the two connectors together with fiberglass tape assuring their temperature will be the same? On my plane the cylinder temperature does not use a thermocouple but a temperature sensing probe screwed into the cylinder head in which its resistance varies with temperature so no special connectors required. It is adjustable so I set it right on a redline. I also used fixed resistors to avoid the ageing problem with rheostats.
 
ARTRR said:
Exactly! That’s why I am stressing the direct connection of the wires. The Omegaconnectors does just that providing the thermocouple wires are matched to the connector.
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You keep suggesting these "Omega" connectors, but have you noticed that they're $8 each (vs. even $1.35/per for the EI red connectors)? My Twin has 12 EGT and 12 CHT probes, each of which has 2 wires that have to be spliced together. So that's, at a minimum, 48 connectors needed to wire up the system. At $8/per, that's nearly $400 in just connectors...
 
Crimp two ring amp connectors then use a #6 screw and nut to join them.
 
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