Fire alarm what is this?

Doomed · Feb 13, 2019

Called to a hotel where the spark doing a refit took down something and then said that he had no idea what it was so they better call someone else.
I then got called in and I have no idea what it is, apsrt from its the end of line on the fire alrm circuit.

[ElectriciansForums.net] Fire alarm what is this?

SparkyChick · Feb 13, 2019

I'm going to hazard a guess at an ageing heat detector.

westward10 · Feb 13, 2019

Looks like an old heat detector. It has been painted, if you scratch some off you will probably find the dome is metal.

westward10 · Feb 13, 2019

Snap.

Deleted member 26818 · Feb 13, 2019

Is that an end of line resistor there?

westward10 · Feb 13, 2019

I see it was manufactured by AFA (Associated Fire Alarms) now AFA Minerva.

Nelder · Feb 14, 2019

My guess is its an end of line resistor.

Diver233 · Feb 22, 2019

Old heat detector (not been made for around 20yrs plus).If you are replacing it make sure you check the cable as it could be 30-40 years old.

Blaspark · Feb 22, 2019

Rs 485 end of line resistor should have 3 resistors no? Manchester bus powered has 1 resistor and one capacitor. What's this system?

Blaspark · Feb 22, 2019

There's not enough terminals for extra power cables? Therefore that cable is power? And maybe power plus data?

Automation ATO · Feb 25, 2019

This should be Old heat detector， It looks like it has some history. My uncle's old house, with three of these, can't work now

bagpuss_24 · Nov 15, 2022

VERY late to the party with this.
It's a "Life Saver" heat detector; initially manufactured and installed by Minerva Fire Defence and then continued to be installed when they became AFA-Minerva (when EMI merged together).
There is a bi-metallic strip inside, the devices are normally open circuit, when heated up, the bi-metallic strip shorts the alarm circuit to sound it. Some had 220k resistors in.
Most of the systems these were installed on were the CT1 and CT6 panels - these operated from batteries, and powered an inverter.
The Zone pair had 220v DC on it (not 24v as most people would assume).