MR I agree it is messy but I disagree with your statement saying the landlord is the RP of the common areas. An employer’s workplace extends outside the building therefore includes the common area. (See definition below.)
Art 3(a) defines the employer as the RP of this area but only where the RP has control. The RP doesn’t have control of the workplaces on the other floors or for instance the fabric of the building. I agree the landlord has total control over the fabric of the building therefore is a PHC and subject the art 5(3). Consequently if a RP needs an exit to comply with art 14 and the landlord refuses, both may be guilty of an offence depending on circumstances. Providing the RP has done everything in his power to convince the landlord, the RP would use art 33 as a defence not so the landlord. This would apply to any of the articles, or part of, the landlord has control over, fire alarm, or sprinklers take your pick.
Art 2 Definitions
“workplace" means any premises or parts of premises, not being domestic premises, used for the purposes of an employer's undertaking and which are made available to an employee of the employer as a place of work and includes –
(a) Any place within the premises to which such employee has access while at work; and
(b) Any room, lobby, corridor, staircase, road, or other place
(i) Used as a means of access to or egress from that place of work; or
(ii) Where facilities are provided for use in connection with that place of work, other than a public road
Sorry to butt in Kurnal a terrible trait of mine but I do think the word premises refers to the individual workplace, what we called an occupancy under the FPA, and not the building. In this case the RP of the workplace (premises) who is creating the explosive atmosphere must co-ordinate the implementation of all the measures required by this Part to be taken to protect relevant persons from any risk from the explosive atmosphere.