Solar · Maintenance
What should I look for on my solar DC and AC isolators?
Short answer
Look without opening them: the case should be intact, the switch clearly on or off, cable glands facing down or sideways, and no condensation, rust, scorching or melted plastic. BRE fire investigations found water getting into outdoor DC isolators was a leading cause. Only switch a DC isolator if your manual says you may.
Last checked 24 September 2026 · 1 source
In more detail
- BRE: several isolators on exposed exterior walls filled with water, all with upward-facing cable glands.
- Sun-bleached, cracked or brittle enclosures on south walls should be replaced by an electrician.
- Many modern inverters have an integrated DC switch; separate roof-level or loft DC isolators may also exist.
- Safety: DC from panels is live whenever light falls on them; the AC isolator does not make the DC side safe.
The facts, dated
- 01Water ingress into DC isolators with upward-facing cable glands recorded in BRE incidents
market_data · UK · checked 24 September 2026 · GOV.UK
Sources
Last checked: 24 September 2026