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AU4 – 1-3/8″ A/F

Technical Data

Plan and side view diagrams of the Termate standoff insulators in the AU4 footprint. Labels show width across flats is 1 and 3/8 inches, width across corners is 1 and 1/2 inches, base diameter is 1 and 1/4 inches, and shoulder height is 3/8 inches. Other dimensions are labelled with a letter, indicating a specific measurement in the table below.

For smaller sizes click here

For larger sizes click here

Part number3D ModelHeight
Depth [D]
AU4-030-014AU4-030-014 STEP file1³⁄₁₆¼—20 UNC⁵⁄₁₆62200120060
AU4-030-516AU4-030-516 STEP file1³⁄₁₆⁵⁄₁₆—18 UNC172800170060
AU4-035-014AU4-035-014 STEP file1⅜¼—20 UNC⁵⁄₁₆62200110060
AU4-035-516AU4-035-516 STEP file1⅜⁵⁄₁₆—18 UNC172900160060
AU4-035-038AU4-035-038 STEP file1⅜—16 UNC323400220060
AU4-040-014AU4-040-014 STEP file1⁹⁄₁₆¼—20 UNC⁵⁄₁₆62200100050
AU4-040-516AU4-040-516 STEP file1⁹⁄₁₆⁵⁄₁₆—18 UNC172900150050
AU4-040-038AU4-040-038 STEP file1⁹⁄₁₆—16 UNC323500210050
AU4-045-014AU4-045-014 STEP file¼—20 UNC⁵⁄₁₆6220090050
AU4-045-516AU4-045-516 STEP file⁵⁄₁₆—18 UNC173000140050
AU4-045-038AU4-045-038 STEP file—16 UNC323600200050
AU4-050-014AU4-050-014 STEP file2¼—20 UNC⁵⁄₁₆6220080025
AU4-050-516AU4-050-516 STEP file2⁵⁄₁₆—18 UNC173100130025
AU4-050-038AU4-050-038 STEP file2—16 UNC323700190025
AU4-050-012AU4-050-012 STEP file2½—13 UNC564800250025
AU4-060-516AU4-060-516 STEP file2⅜⁵⁄₁₆—18 UNC173200120025
AU4-060-038AU4-060-038 STEP file2⅜—16 UNC323800170025
AU4-060-012AU4-060-012 STEP file2⅜½—13 UNC564900210025

* Fixing details: Hole diameter = Standoff thread size [M]+¹⁄₁₆

** Tensile and Cantilever Strength figures are based on tests carried out at normal room temperature, nominal 73.4 °F

UL Listing

UL Recognised Component

File Number E505645



Glass Reinforced Polyamide 6.6

Insert Material


Operating Temperature

−40 °F to +266 °F


UL 94 V-0

Oxygen Index


Glow Wire

960 °C


Equipment Voltage, Ue
1000 V AC, 1500 V DC
Insulation Voltage, Ui
1000 V AC, 1500 V DC
Impulse Voltage, Uimp
12 kV

Standoff Insulators:


Termate’s AU4 standoff insulator range provides excellent electrical insulation and mechanical strength for a variety of applications. Standoff insulators can also be referred to as post insulators, egg insulators, bobbin insulators, or busbar isolators.

This standoff insulator range is available in heights from 1³⁄₁₆ inch to 2⅜ inch and insert sizes of ¼″-20 to ½″—13 UNC. Technical data is found on the table above which displays heights, thread size and depth, maximum tightening torques, tensile and cantilever strengths, and box quantities available.

Please note that while we have referenced imperial (inch) dimensions, the height and width of the range is identical to the metric sizes. The .STEP files attached are the correct dimensions.

  • Made from UL 94 V-0 rated, self-extinguishing material
  • Halogen Free
  • Operating temperature range of −40 °F to +266 °F 
  • Insulation voltage of up to 1000 V AC, 1500 V DC
  • Equipment voltage of up to 1000 V AC, 1500 V DC
  • UL Recognised Component; file number E505645

Our standoff insulators are made from a halogen-free glass-reinforced material, which was specifically chosen for its mechanical and electrical insulation properties.

Brass inserts are used due to this alloy’s resistance to corrosion. The injection moulding process, combined with our excellent quality control and inspection procedures, results in a consistent product across every production run.


Termate carries out rigorous and appropriate testing on all our products. The AU4 range of standoff insulators successfully passed extensive testing to ensure their electrical and mechanical capabilities.

AU4 standoff insulators meet the requirements for UL 94 V-0. UL 94 being a standard for the safety of flammability of plastic materials for parts in devices and appliances released by the Underwriters Laboratories.

Our Standoff insulator range is a UL Recognised Component and are listed under the product category “Panelboard and Switchboard Accessories – Component”, more information can be found at UL Product IQ.



Our standoff insulators are suitable for assemblies up to 1000 V AC or up to 1500 V DC. They are intended to safely and securely support and insulate busbars and other live conductors by maintaining a distance between two surfaces. In these types of installations, the electrical insulation and the mechanical strength of the support are paramount. Usual installations are within:

  • Energy Storage Systems and Equipment (UL9540)
  • Electrical Panelboards (UL67)
  • Industrial Control Panels (UL508A)
  • Switchboards (UL891)
  • Metal-Enclosed Low-Voltage Power Circuit Breaker Switchgear (UL 1558)
  • Inverters, Converters, Controllers and Interconnection System Equipment for Use With Distributed Energy Resources (UL1741)

These electrical installations can be found in a wide range of sectors including power distribution, rail (rolling stock & trackside), renewable energy, UPS (temporary and emergency power), and data centre power distribution.

At Termate, we have been designing and manufacturing electrical insulating parts and components, such as our standoff insulators, from our Nottingham UK based factory for over 60 years. Quality is ensured on every product we produce. Our knowledge and experience of the raw materials used, the performance requirements, and the application of our products allow us to provide products that are safe and fit for purpose.

Termate is committed to the highest standard of customer focus and we have made every effort to maintain the accuracy and completeness of the information provided in this data. Where improvements to our products affect their installation and usage we endeavour to contact any customers who may be affected.

Warranty as stated in our Terms and Conditions of Trading is void if any modification is made to the warranted product.