Hello, after 30+ years of operation, some of our terminal blocks are falling apart. I am curious if anyone has found a good replacement that will fit on the channel that is original to many of the junction boxes. I believe GE's part number for these blocks is 302A4584P024. The main point of failure is the brackets that hold the termial chain in place, which i can probably figure out in house. But if there is a product out there that you have been using, i'd love to hear about it. Thanks much!

 

@egg,

You can use any type of terminal block that can stand the temperature of the environment. I believe there are some Phoenix DIN-rail terminal blocks that are properly rated, but they kind of suffer the same problem--those clamps at the ends won't last very long. Not a great design by just about any manufacturer.

Some people believe (mistakenly) that the terminals must be Chromel and Alumel--and that's just not true. You can use the style of terminal board with two screws, one on each side, and you can crip any terminal on the ends of the T/C extension wire. Two cold junctions in the same ambient temperature cancel each other out--that's why you see one side of each wire under the clamping plate on one side of the screw and the other side of the wire under the other side of the clamping plate on the opposite side of the screw. That creates "two" cold junctions, in the same ambient in the JB, so they cancel each other out. It doesn't hurt to use Chromel and Alumel crimp terminals, but it's not necessary as long as the two bare parts of the two leads don't touch each other. (Machines have failed performance tests because two or three exhaust T/Cs were not wired properly--and simply making sure the bare ends don't touch each other solved the "performance issue.")

So, as you know you need some terminal board material(s) that will withstand the temperature inside and around the outside of the JB. (GE has a part number for the clamps at each end of the string of terminals, too.) You can use DIN-rail mounted terminals, or a full "Bakelite" terminal board (or boards). You simply have to ensure that no bare wires touch each other--OR that BOTH Chromel wires touch each other AND BOTH Alumel wires touch each other (no cold junction created by this arrangement). You can put Chromel and Alumel crimps on the T/C wires and put the two Chromel crimps under one screw, and the two Alumel crimps under one screw (again--no cold junctions created by this arrangement). You just need to make sure the two connections of a single T/C are either not touching each other or are both touching each other--and Bob's your uncle!

Eazee. Pezee.

 

Now that I am looking at the terminal board, I see that I could just replace the channel with din rail and get whatever I need. The offset brackets could just stay in place. I was thinking that it would be easier to get a terminal block that would fit in the original groove but like you are getting at, it would be much more simple to just replace with DIN. Thanks for the help!

 

Now that I am looking at the terminal board, I see that I could just replace the channel with din rail and get whatever I need. The offset brackets could just stay in place. I was thinking that it would be easier to get a terminal block that would fit in the original groove but like you are getting at, it would be much more simple to just replace with DIN. Thanks for the help!

We are having the same issues.

There are a couple of solutions we have used dependent on location and DIN rail configuration.

The following connecters are ok, the also sell lugs that are suited that I think offer a better connection.

Barrier Terminal Blocks (rated to 220°C) - TC Direct

Thermocouple Spade and Ring Lugs - TC Direct