Cable Sheath Testing
Professional Sheath Testing for HV & LV Power Cables
We provide accurate cable sheath testing services for high and low voltage cable systems across the UK. Our engineers test the integrity of cable outer sheaths to detect damage, moisture ingress and weak points that may affect system performance.
Why Sheath Testing Is Important
The outer sheath of a cable protects the insulation and conductor from mechanical damage and environmental exposure. If compromised, water or contaminants can enter the cable and lead to faults, safety risks and early failure.
Sheath testing helps:
- Identify damage from installation or site activity
- Detect water ingress or insulation compromise
- Prevent cable faults before energisation
- Verify integrity before commissioning
- Support long-term asset reliability
We carry out sheath testing as part of new installations, fault diagnosis and condition-based maintenance.
How It Works
Sheath testing involves applying a high-voltage DC test between the cable sheath and earth. Any insulation breakdown or defect results in a measurable current, which we use to pinpoint issues or confirm sheath integrity.
We test:
- Single-core HV cables with bonded or unbonded sheaths
- Multicore LV power and control cables
- Sheath faults on underground cable runs
- XLPE and PILC cable types
- Cables in substations, ducts and trenches
Testing is non-destructive and fully compliant with UK safety and industry standards.
Clear Reporting & Next Steps
All results are recorded in a formal report, with values, observations and recommendations for repair or re-testing if required.
Frequently Asked Questions
What is cable sheath testing?
It is a test that checks the condition of a cable’s outer sheath to confirm it is free from defects that could allow water or contaminants to enter.
When should sheath testing be done?
Sheath testing is recommended after cable installation, before commissioning, or as part of ongoing maintenance to check for damage or wear.
Do you locate sheath faults if found?
Yes. If a defect is detected, we can carry out sheath fault location using step voltage or bridge methods to identify the fault point for repair.
Is the test damaging to the cable?
No. When done correctly, sheath testing is non-destructive and safe for both new and operational cables.