Having installed and commissioned hundreds of Aico / Ei Electronics systems across domestic and light commercial properties over the past 25 years, a few practical field engineering points that will save you headaches:
1. Baseplate Locking Tangs:
While cutting the locking tangs on the easi-fit base makes removal easier, keep in mind that if building control or a landlord inspection ever inspects it, BS 5839-6 (Grade D1/D2) specifies tamper resistance. You don't actually need to butcher the baseplate or gouge plasterboard with a heavy screwdriver: Aico moulds a dedicated release slot on the front lip. If you slide a small 3mm or 3.5mm terminal driver flat into that horizontal slot and push straight back towards the hinge, the internal locking lever unlatches cleanly with zero levering force and the head unit slides forward effortlessly.
2. Garage Detection & Fire Compartmentation:
Make sure the unit going into the garage is specifically a Class A1 Heat Alarm (e.g. Ei144e or Ei3014), never an optical smoke detector. Vehicle exhaust fumes, cold damp air, and dust will trigger constant nuisance alarms on an optical head.
Also, if running that 3-core & earth into the garage means drilling through the fire compartment wall (typically 12.5mm double plasterboard or blockwork into an attached garage), you are breaching the fire barrier. Any penetrations must be sealed with certified intumescent acoustic mastic to satisfy Part B.
3. The RF Hybrid Alternative (RadioLINK+):
If fishing 3-core & earth past that awkward inaccessible joist into the garage is a nightmare, you don't actually need to pull physical cable to every single point. Aico / Ei systems support hybrid hardwired-RF meshing. If you pop an Ei100MRF (for the 140e series) or Ei3000MRF module into one of your hardwired hall/utility bases, and fit an RF module in the garage base, that single RF bridge will transmit the interconnect trigger across the whole hardwired loop. You just house-code them together (press the house-code button on the RF base until the blue LED flashes, then code the heads).
4. Single Phase & Circuit Isolation:
Ensure that all alarms on that hardwired Interconnect (IC) line are supplied from the exact same phase and circuit. Mixing feeds across different circuits or split RCD boards where neutrals are separate can cause voltage differentials across the IC terminal, which leads to intermittent 3 AM phantom alarms. Always sleeve the grey wire at every base and junction box (with brown or black over-sleeving) so anyone working on it later knows it's the live interconnect trigger, not a neutral.
5. Locate Switch (Ei450):
When you have 4+ interconnected alarms across hall, landing, utility, and garage, if one goes off in the middle of the night, tracking down which unit tripped is chaotic. Consider fitting a battery-powered Ei450 RadioLINK Alarm Controller on the wall in the hall. It gives you a single 'Locate' button that silences all sounders except the originating unit, so you can immediately see which head detected smoke/heat.