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Indoor Bus-Bar Insulators

The main economical advantage of Sreka indoor bus-bar insulators is that they are compact and space saving, allowing the design engineer freedom to utilize them for such jobs as bus-bar insulators, cable terminals and supports for various electrical devices.

Plating of metal parts – Zinc Dichromate Passivate
The steel inserts are zinc plated followed by a dichromate passivating treatment.  This finish offers a sound protection against industrial, atmospheric and chemical corrosion.

Inserts – Mild Steel
The insert is not a conducting part and therefore can be made of material most suitable to withstand high mechanical stresses.  To provide reliable toughness these are manufactured from hexagonal mild steel bar.  Thread types are of metric dimensions.

Moulding – Glass Fortified Nylon
Whilst being compact and space saving with adequate clearances and creepage paths, other less obvious features are included.

For performance in moulded parts, glass fortified nylon has been noted for superiority over general unfortified nylons.  The addition of glass fibres to nylon increases strength and dimensional stability, lowers water absorption (24-hour Water Absorption Test ASTM Method: Unfortified, 1.8%; 25% Glass Fortified, 1.2%), dramatically increases deflection temperature and substantially increases mechanical strength.

Physical Strength
*Cross breaking shear test

S25 – 344 lbf max. (1.53 kN)
S35 – 3150 lbf max. (14.01 kN)
S50 – 4850 lbf max. (21.57 kN)

*Withdrawal Strength Test on Inserts
S25 – 1214 lbf max. (5.40 kN)
S35 – 4500 lbf max. (20.02 kN)
S50 – 5900 lbf max. (26.24 kN)

*Electrical Dry Withstand Voltage Test
Flashover Test Between Inserts

Type S25 – 10kV AC / 10kV DC    Type S35 – 40kV AC / 40kV DC    Type S50 – 50Kv AC / 50Kv DC

*Independent test laboratories test reports are available for inspection.


A B C Insert
S25 25 16 22 6M 26 18g
S35 35 25 50 8M 55 72g
S50 50 38 60 10M 68 147g