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iQ means "Interoperability Quotient", and is our proprietary, patented technology which allows the use of identical components on all of the Concentric Devices' product lines. This allows all our products to act effectively and efficiently together. Learn more...

Just some of the benefits to terminal block design and implementation through iQ Technology are captive hardware, faster termination, greater design flexibility, increased safety, laser strip ID, and higher circuit density. Read more...


Concentric Devices terminal blocks are manufactured in the United States to the most demanding specifications. See the entire physical specifications list.

iQ technology produces the terminal block with the fastest installation and termination, safest operation and best circuit identification available. View the product.

Fully captive hardware and isolated electrical paths provide the safest and fastest way to shunt circuits for CT testing. A simple turn of a screw does it. No lost hardware, ever. View the product.

Interruptible Link provides circuit opening with captive hardware and isolated electrical paths. No loose hardware or potential contact with live buss bars. A simple turn of a screw does it. View the product.

For maximum design flexibility and circuit density, use din rail mounting.

For those customers who want to stick with traditional panel mounting, our panel-mount hardware fits all major patterns for screwmounting, making switching to our terminal blocks simple. Read more...

Never loose track of circuits again. Customize, laser etched ID strips identify your specific circuit. Find out more...

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iQ Technology packs more circuits per area than the competition - 20%-50% more!

Our terminal block construction is made up of three pieces, which come assembled from our manufacturing facility. We have the base piece, which is loaded with bus bars for the electrical path. Next we have a housing that holds springs and screws in each of the cavities, which provide various electrical connections. Finally, we have the cover for the housing, which holds the springs and screws in place. The cover offers electrical isolation from the live components of the terminal block.

See a comparison of old vs. new terminal block construction, and the benefits of our "iQ Technology".


  • Current Bars: Brass per QQ-N-290
  • Plating: Copper flash with nickel plate per QQ-N
  • Captive Screws: 8-32 Brass per QQ-B-321
  • Current Bar Spacing: 0.562 inch center to center


  • Glass Reinforced Polyester: Modified free of halogens, fluorocarbons, chlorinated
    hydro-carbons, silicones, asbestos, cadmium and formaldehyde
  • Flammability Rating: 94-VO
  • Continuous Operating Temperature: minus 55 degrees (minus 48C) to plus 300 degrees F (plus 149C)
  • Short Term Operating Temperature: plus 338 degrees F (plus 170C)


  • Voltage Rating: 600 volts maximum (RMS)
  • Current Rating: 30 amps ( 50 or 60 Hz or DC )
  • Dielectric Withstand Voltage: 4000 volts (RMS)


  • Wire Size: AWG 10 maximum
  • Screw Torque: 10 to 12 LB-IN ( 1.1 to1.4 N-M )
  • Mounting Method: DIN Rail clamp (3.5mm) or Panel Mount
  • Wire Termination Technique: Ring or Spade lug