Reduced low voltage supply is the standard for portable tools and temporary lighting on construction sites in the UK, using a centre tapped transformer so that the voltage to earth is halved. Emergency lighting on such a site is a different problem from emergency lighting in a finished building, because the building is changing every week and the escape routes change with it.
Why reduced voltage is used
It limits the severity of an electric shock in the wet, dirty, mechanically damaging conditions of a site. Guidance on electrical safety at work points site installations that way, and it is why site lighting, transformers and tool supplies are a distinct product family. Fittings intended for it are built for the voltage and for the environment rather than for appearance.
Emergency lighting during construction
A site under construction still has to allow people to escape, and escape routes have to be usable when the lighting fails. The arrangement is usually self contained battery units on the designated routes and at stairs, moved as the routes move, rather than the permanent installation that will eventually serve the building. The site fire plan should show where they are, and it should be revised when the routes change.
Temporary and permanent are different systems
The permanent emergency lighting is commissioned at the end of the job against the building's design. The temporary arrangement exists throughout the works and is nobody's product purchase, which is why it is the one most often left to accumulate rather than being designed. Testing it is a site management task and the record belongs in the site file.
Plant rooms and specialist areas
Reduced voltage lighting also appears in some plant and maintenance areas of finished buildings for the same reason. Where it does, the emergency lighting in that area has to work at that supply, which is a specification point that gets missed when a building's emergency lighting is procured as one package.
Questions people ask about 110v emergency lighting
Is emergency lighting required on a construction site?
Escape routes have to be usable if the lighting fails, so yes in substance. The arrangement is temporary and moves with the works.
Who is responsible during construction?
The principal contractor for the site's own arrangements, with the duties under construction and fire safety law running in parallel.
Can permanent fittings be used temporarily?
Commissioning the permanent system early and using it during the works is sometimes done and needs care, because damage and dust during the works can leave fittings that were commissioned and are no longer working.