Terminal Block Types

[stew1234]

I have used a variety of screw down terminal block types in DIY projects but haven't put much thought into them beyond using what was in the kit. It seems most opt to use screw down terminal blocks with bare wire.

I'm putting together a DAC together now and am planning to use solid core wire, at least for signal wiring, and am thinking about direct soldering the signal wires. This would make it a pain to move things around in the future so I am also thinking about the best terminal block option.

Most terminal blocks, like the first one I have below, have a rectangular entry. If I'm using solid core wire, I'm worried that that connection would not be as good as if using stranded wire since it wouldn't compress to fill the contact space. I am also planning to use larger AWG wire for the power lines (15awg or so).

Is there any advantage to using the second type of terminal block listed below that has a scalloped terminal block bed? Alternatively, would using a flat ferrule crimp connection, if using the first one, provide the ideal connection?

I have also seen the third type of connectors with an elevator-style clamping mechanism that provides greater clamping force. These appear to be ideal for vibration-prone applications (not a concern with home audio use) so I doubt there would be any advantage over the current terminal block I have.

Aside from direct solder, it seems ferrule connections would, in theory, provide the best connections, but you are adding additional solder and connections points, so maybe bare wire into the terminal block is best. That being said, when using solid core wire what would the best approach be?


https://media.digikey.com/pdf/Data Sheets/Phoenix Contact PDFs/1935187.pdf (Current terminal block; 26-12awg)

:: Weco - 978 (-DS) :: (curved terminal block bed; higher current 26-12awg)

:: Weco - 141-A-111 :: (elevator style clamping mechanism; 30-14awg)

 

[indianajo]

Alternatively, would using a flat ferrule crimp connection, if using the first one, provide the ideal connection?
Aside from direct solder, it seems ferrule connections would, in theory, provide the best connections, but you are adding additional solder and connections points, so maybe bare wire into the terminal block is best.

I use different terminal blocks on my projects for power wire (16-10 ga) and signal wire (26-20 ga). The big ones, the screw end misses the small wires most of the time and won't capture them.
We had good reliability on low level signals in the factory with crimped spade lugs, under the old fashioned barrier terminal blocks. Euro caged wire blocks had not been invented yet. That test installation lasted 12 years without connections becoming a problem. Crimp connectors made properly meld the copper into a mass and exclude oxygen, which causes copper oxide. See the AMP application notes about crimping. Screw terminals also have high pressure from the screws and exclude oxygen.
The current fashion of punch blocks and ribbon cable is a complete fraud IMHO, making products that will work well through the one year warrenty period. Not beyond. There is not enough force in those pinch connections to exclude oxygen. The telephone industry invented punchdown blocks for telephone signals, which were 48 v at medium current. 48 v with 600 ohm impedance will burn off thin copper oxide, 12 v will not in my experience. Even 24 v modems were a problem with punch blocks, leading my employer to have thousands of feet of telephone cable ripped out of the complex about 1990 and replaced by glass fiber.
I'm going through old PA gear and trying to get the line level signals to actually flow, which is a problem. Removing & replacing a punch down connection will make it work for at least 6 months. !@#$%&^&*
So use different screw blocks for large & small wires, is my advice. Square versus round hole, doesn't matter, the screw surface against the bottom is what makes the connection and excludes the oxygen.
Note there are import crimp terminals now which lack enough material in the sleeve to achieve good pressure on the copper strands and meld them. Had some radio shack yellow shank terminals melt out at 30 amps in a used car I bought. Ignition circuit. Changed to ideal brand terminals, no more problem. Equivalent quality IMHO are AMP (now TE connectivity) T&B, Ideal, Panduit, 3M. Dorman is pretty close. Not the bargain terminals on ebay/amazon/alibaba.