As per Chris’s comments above, this will depend on your lease document.
Forgive me for my long-winded response, I’m thinking out loud here and using a process of elimination to help you arrive at my answer simply if it were me in your shoes and again making several assumptions with my answer.
Most businesses we have experience with, use an ADLS (Auckland District Law Society) Agreement to Lease, or Deed of Lease. It will also depend on the edition of this document if it is in this format. I also assume the emergency lighting is to illuminate the exits to the building in the event of an emergency? On the most recent edition of the ADLS Agreement to Lease, line item (4) of the outgoings schedule states “New Zealand Fire Service charges and the maintenance charges in respect of all fire detection and fire fighting equipment.” are payable by the Tenant, again assuming you are on a net lease (i.e. responsible for paying all opex) and this line item of the outgoings has not been deleted, then as a general rule of thumb, Landlords are required to provide the fire fighting equipment, the Tenants are then responsible for maintaining said equipment. As this is neither fire fighting or fire detection equipment, I have looked into line item (7) of the outgoings schedule which states “Cleaning, maintenance and repair charges including charges for repainting, decorative repairs and the maintenance and repair of building services to the extent that such charges do not comprise part of the cost of a service maintenance contract, but excluding charges for structural repairs to the building (minor repairs to the roof of the building shall not be a structural repair), repairs due to defects in design or construction, inherent defects in the building and renewal or replacement of building services.” Personally, I would classify the emergency lighting as “building services” – here is also a link to give examples of building services https://www.designingbuildings.co.uk/wiki/Building_services and as per this section (7) of the Outgoings in the ADLS Agreement to Lease FIFTH EDITION 2012 (4) this would imply it is the responsibility of the Landlord.
If your Lease is not in this format, I would speak to your solicitor.
Hope this helps 🙂