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Piercing insulation is `60% faster than screwing`

01 January, 2001

Piercing insulation is `60% faster than screwing`

German terminal specialist Wieland has developed a terminal block which pierces the insulation of the connecting wires, avoiding the need to strip insulation, or to crimp ferrules onto the ends of the wires. The result, claims the company, is a saving in wiring time of up to 60% compared to conventional screw terminals.

Although the piercing technology, known as IDC (insulation displacement connection), is widely used for signal and low-current connections, it is less common in higher current applications. Wieland says that its DIN-rail-mounting system, called Taris, can accommodate wires up to 2.5mm2 and can carry currents of up to 25A at 600V.

Connections are made simply by pushing the wire into a hole in the terminal block and then inserting a standard screwdriver into an adjacent hole and using it as a lever to pierce the insulation and make the connection in one action.

Thomas Beck, Wieland`s Taris product manager, asserts that the system is "the smallest terminal block with IDC connections on the market". For cables up to 1mm2, the terminals are 5mm wide; for cross-sections up to 2.5mm2, they are 6mm wide.

Wieland has conducted tests which showed that it takes an average of 12.8 minutes to make 50 screw-type connections by hand. Using a power screwdriver cuts this to 8.9 min while 50 cage-clamp terminals (which avoid the need for crimping, but still require the insulation to be stripped) can be connected in 5.4 minutes. By comparison, says Beck, it takes just 3.1 minutes to make 50 Taris connections.

To ensure a reliable connection, the insulation is pierced and connections are made separately on both sides of the wire. These connections are said to be gas-tight and to resist vibration and corrosion. Test points are built into the terminals and there is a visual indication of the status of the circuit.

Wieland has designed the connectors to be re-used up to 20 times.

At present there are more than 20 items in the Taris family including single- and double-tier blocks, neutral feed-through blocks and screwless jumper bars. Further versions are planned, including hybrid IDC and screw blocks.

Thomas Beck admits that the IDC technology has its limitations. He does not expect it to be used for wires larger than 6mm2. Screw terminals, by contrast, can accommodate wires up to 35mm2. "Screw terminals will not disappear," says Beck.

He sees the new system being particularly useful for connecting items such as sensors in installations where many connections need to be made.

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