STS 300 Replacement Parts

Available for direct replacement of damaged circuit boards. They need to be specified by voltage 12VDC, 24VDC, 120VAC, 240VAC. Some retrofit capabilities to older STS 300 series models are possible. Contact us to confirm.

K78160A Aluminum Grounding Clamp Replacement Kit (RK-1) to replace damaged or worn parts. Includes stainless steel contact points and all electrical connection hardware.

K78160ASRS Aluminum Grounding Clamp Repair Kit (RK-2) equipped with Strain Release option. Includes contact points, all electrical connection hardware and strain release cable and hardware.

Phenolic Insulator — Part #K78166

Part #K78166 is the OEM phenolic insulator that connects the grounding cable to the circuit board inside an STS 300 ground monitoring system. It’s molded from phenolic, a rigid thermoset that insulates well and shrugs off heat, so the connection stays clean and the monitor keeps reading the ground path correctly.

The kit has what you need for a field repair: the white phenolic insulator and nut, the brass cable connector, and the internal wiring. It fits both styles of STS grounding cable, so you don’t have to match cable generations.

Replace it when the connector cracks, the insulator chips, or the monitor starts giving intermittent or failed readings that point to the cable-to-board connection and not the clamp. Phenolic is the material here for a plain reason: it takes daily clamp handling without cracking or going conductive.

Not sure which part you need? Request a quote or contact us with your system’s part number. It’s one of several replacement parts we stock for STS 300 systems.

Frequently Asked Questions

What is a phenolic insulator?

A phenolic insulator is a part molded from phenolic resin, a thermoset plastic that resists heat and doesn’t conduct electricity. In an STS 300, it connects the grounding cable to the circuit board and keeps that junction isolated.

Is a phenolic insulator the same as a phenolic bushing?

For this part, yes. “Phenolic bushing” and “phenolic insulator” describe the same insulating connector. STS Part #K78166 fits both styles of STS grounding cable.

How do I replace the phenolic insulator on an STS 300?

Replace it when the connector is cracked or the readings turn intermittent. The K78166 kit includes the insulator, nut, brass connector, and wiring, and it connects the grounding cable to the circuit board.

Will it fit my STS grounding cable?

Yes. Part #K78166 works with both styles of STS grounding cable.

Available for all STS 300 Series models. The red and green lamp assemblies are compatible with both LED and incandescent bulbs.  Bulbs sold separately.

Incandescent or LED bulbs are available for spares or direct replacement. Specify voltage (12VDC, 24VDC, 120VAC or 240VAC). Please specify the color for 120VAC bulbs. All DC bulbs are white and can be used in 12VDC and 24VDC systems.