Do Not Switch On Sign

Do Not Switch On Sign

A do not switch on sign is fitted to isolators, control panels, and machine start buttons to warn crew that equipment must remain de-energised, usually while maintenance, testing, or repair work is underway. It is one of the most frequently used prohibition signs in an engine room or electrical switchroom, since almost every piece of shipboard machinery has a point of electrical isolation that needs marking during lockout procedures. Displayed directly on the switch, breaker, or starter panel itself, the sign prevents another crew member from restoring power without realising work is still in progress nearby.

The pictogram follows the ISO 7010 prohibition format: a black hand pressing a switch, overlaid with the standard red circle and diagonal bar on a white background. This do not switch on sign is understood instantly by crew of any nationality, an important feature on multinational-crewed vessels where a misread warning could have serious consequences. It carries IMPA code 33.8552 and ISSA code 47.585.52, the catalogue references used by ship chandlers and marine suppliers when restocking electrical safety signage, and Safety Sign Hub holds this sign in stock for prompt despatch.

Marking Isolated Circuits During Maintenance

Electricians and engineers typically fit this sign the moment a circuit is isolated, whether that’s a motor starter being serviced, a switchboard panel under test, or a deck lighting circuit being repaired. It should stay in place for the entire duration of the work and only be removed once the responsible person has confirmed it is safe to re-energise. On vessels using formal lockout-tagout procedures, the sign works alongside physical locks and tags rather than replacing them, giving a clear visual cue to anyone passing through the space. Pairing it with our full range of prohibition signs covering related isolation and access warnings helps build a complete electrical safety signage set for engine rooms and switchrooms.

Signs are produced on fire-retardant material, with a photoluminescent option for switchrooms and machinery spaces that may lose lighting during a fault or power failure. UV-stable inks and a protective laminate resist the oil, dust, and humidity common in engine rooms, so the warning stays sharp rather than smudging when handled during frequent isolation and de-isolation cycles. This is particularly important for a do not switch on sign, since it is often reused across many short maintenance jobs rather than left permanently fixed in one place, and needs to withstand repeated handling without losing legibility.

Available as a self-adhesive label suited to switch faces and control panels, or as a rigid panel for larger switchboard installations, this sign carries the same IMPA 33.8552 and ISSA 47.585.52 codes across both formats. Keeping a small stock of both on board means engineers always have a sign ready the moment isolation work begins, rather than delaying the job while searching the stores for the correct label.

Reinforcing Electrical Isolation Procedures

Electrical isolation warnings like this one reflect the pictogram principles set out in ISO 7010 and the layout conventions of AS 1319, giving crew a standard visual language for de-energised equipment regardless of which vessel they are serving on. Applying the same sign consistently across a fleet means an electrician transferring between sister ships recognises isolation warnings immediately, without needing to learn a different informal marking system on each vessel.

On a well-run vessel, this sign becomes part of the standard permit-to-work paperwork: it is issued alongside the lockout tag when isolation is confirmed, and both are removed together once testing shows the circuit is safe to re-energise. Some engineers keep a laminated card at the switchboard listing which circuits currently carry this warning, cross-referenced against the day’s job list, so nothing is missed during a busy maintenance period. Because isolation work can happen at short notice, having a ready supply of these signs in the electrical workshop, rather than only in general ship’s stores, keeps the response quick whenever a new job begins.