Thermocouple Quick Disconnect and Theory


Thread Starter


I've done a fair bit of reading on thermocouple connections and one question that stands out is why are there special thermocouple terminal blocks? From what I understand, making a splice of two lengths of thermocouple extension wire using standard terminal blocks should present absolutely no problem IF the terminal blocks do not have a temperature gradient across them. I think I can logically infer that there shouldn't be a temperature gradient if the terminal blocks are physically right next to each other and inside a cabinet for example. So what's the deal with special "Thermocouple Rated" terminal blocks?

Second, I'm in search of a quick disconnect method for two thermocouple circuits and a few other wires for discrete I/O (24VDC). They would need to be in the same connector. I'm thinking of putting everything in the same run of liquid-tight conduit and having a Harting style connector on the end. This is for an outdoor application involving a lot of foot traffic and the conduit/sealtite must be on the ground which is why I want a robust connection method and not the usual yellow thermocouple connectors. If what I've said earlier about the different metals in the connector not causing a problem as long as there is no temperature gradient is true then I think this should work.

Can anyone offer their opinion to the contrary?

You're right. As long as you have thermocouple or T/C compensating/extension wire on both sides of the connector, the error will be limited to whatever thermal gradient there is between the connections. Go for it.