What is an electrical isolator for chargers and solar?
An electrical isolator is a device suitable for disconnecting equipment from its electrical supply for isolation. Switching and isolation functions must be checked against the device specification [S1]. The IET's BS 7671:2018+A4:2026 guidance distinguishes these functions; solar inverters need isolation on both AC and DC sides [S2]. Request a labelled isolation plan for your installation. Checked October 2026.
What does an electrical isolator do?
An electrical isolator is a device suitable for separating equipment from its electrical supply. A switch’s ability to operate equipment does not automatically establish its isolation function; check the specified device and standard [S1].
For your site, it matters because maintainers need a clear way to isolate chargers, inverters and other equipment. Request a labelled drawing showing the equipment served by each device. Ask who retains access when the car park or plant room is locked.
How do AC and DC isolators differ on solar installations?
Alternating current (AC) changes direction; direct current (DC) flows in one direction. A solar photovoltaic (PV) inverter converts the panels’ DC output to AC. The IET explains that inverter maintenance requires means of isolation on both sides [S2].
AC and DC switching ratings are different. DC can sustain an arc during switching, so a suitable DC switch-disconnector needs the correct rating and configuration for the array [S2]. Ask for the selected devices and their locations in the handover information. The commercial roof fire safety guide covers the broader emergency-information questions.
What isolation information should your site receive?
For chargers, ask the designer where isolation is provided and how maintenance and emergency switching are addressed [S1]. Do not assume every installation needs the same separate enclosure beside every bay.
For the handover, request labels, operating instructions, access arrangements and the agreed fault-reporting route. HSE says isolation must cover all relevant energy sources and prevent inadvertent reintroduction of energy [S3]. Treat the drawing as information for competent work, rather than permission for staff to open electrical enclosures.
Keep it with your electrical installation certificates. Use Section 722 explained for charger protection and the charging cost tool for the separate operating budget.
Next step
Record your existing equipment in the site check, then get matched with an installer that covers your area.
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Common questions
Must the isolation device be beside the charger?
Have the designer specify the location and device functions for your installation. The IET distinguishes isolation, maintenance switching and emergency switching; one label does not establish all functions [S1].
Can an AC-rated switch be used for solar DC?
Only if it has the appropriate DC rating and configuration. The IET explains that AC and DC ratings differ and that DC interruption requires particular consideration [S2].
Must solar DC isolation always use a separate external box?
Do not assume that layout. The IET discusses selection where the designer chooses external switch-disconnectors. Ask the designer to document the selected means of isolation [S2].
Does an off switch make equipment safe to work on?
Not by itself. HSE requires planned work and secure isolation of all relevant energy sources so energy cannot inadvertently return [S3].
Who should inspect or replace a damaged isolator?
A person competent for that electrical task. HSE requires relevant training and experience; report the damage and arrange competent attendance [S3].
Ask about your site
Sources
- Protective, isolation and switching devices explained, Institution of Engineering and Technology,Last checked 19 October 2026
- Solar photovoltaic DC switch-disconnector selection and configuration, Institution of Engineering and Technology,Last checked 19 October 2026
- Work on electrical equipment, machinery or installations, Health and Safety Executive,Last checked 19 October 2026