Isolator modules protect an addressable loop from a single-point failure. A short circuit anywhere on a loop can take the entire loop offline; isolators segment it, so a fault is confined between two isolators and the rest of the loop keeps reporting.
They come as standalone modules and built into detector bases. Placement is a design decision — more isolators mean smaller affected segments and a higher device count — and many codes set a maximum number of devices that may be lost to one fault, which effectively sets the spacing.
Isolators are loop-specific: match the module to the panel protocol.

Simplex
Simplex 4090-9116 Addressable IDNet Communications Isolator
Sale price$53.85
Regular price$64.62
300+ units in stock
Simplex
Simplex 2081-9027 Isolated Loop Circuit
Sale price$51.95
Regular price$62.34
Not in stock - available on backorder - lead time on request
Edwards
Edwards SIGA-IM2 Isolator Module
Sale price$79.05
Regular price$94.86
Not in stock - available on backorder - lead time on request
Notifier
Notifier N100-ISO SLC Loop Isolator Module, Isolates Against Short Circuits on the SLC
Sale price$97.40
Regular price$116.88
2 units in stock
Secutron
Secutron CSIS-202A1 Supervised Signal Isolator Module
Sale price$70.15
Regular price$84.18
3 units in stock
Kidde
Kidde FX-ISO Analog SLC Fault Isolator Module.
Sale price$77.00
Regular price$92.40
Not in stock - available on backorder - lead time on request
Siemens
Siemens ILED-XC (S54370-B6-A1) Addressable Remote Lamp, Round Plate, Dual Isolators
Sale price$71.95
Regular price$86.34
44 units in stock
Apollo
Apollo SA4705-703APO Soteria UL Switch Monitor Input/Output Module
Sale price$113.50
Regular price$136.20
Not in stock - available on backorder - lead time on request
Simplex
Simplex 4100-3207 Quad IDNet Isolator Module
Sale price$301.45
Regular price$361.74
Not in stock - available on backorder - lead time on request
Siemens
Siemens ILED-XW (S54370-B5-A1) Intelligent Lamp
Sale price$76.60
Regular price$91.92
Not in stock - available on backorder - lead time on request
Siemens
Siemens HLIM (500-033170) Line Isolator
Sale price$65.65
Regular price$78.78
6 units in stock
Monaco
Monaco 729-140-00 Module: Isolator, Intelligent
Sale price$101.85
Regular price$122.22
Not in stock - available on backorder - lead time on request
Potter
Potter PAD300-IM Isolator Module
Sale price$98.40
Regular price$118.08
Not in stock - available on backorder - lead time on request
Kidde Fenwal
Kidde Fenwal 74-200012-002 SmartOne Loop Isolator - 1 Gang Box Mounted.
Sale price$489.55
Regular price$587.46
Not in stock - available on backorder - lead time on request
Edwards
Edwards SIGI-WTMI Waterflow/Tamper Module with Isolator, Edwards
Sale price$85.80
Regular price$102.96
Not in stock - available on backorder - lead time on request
Edwards
Edwards SIGI-SB Signature Detector Base, with Isolator
Sale price$8.15
Regular price$9.78
Not in stock - available on backorder - lead time on request
Edwards
Edwards SIGI-MM1I Module, Monitor with Isolator, Edwards
Sale price$53.55
Regular price$64.26
Not in stock - available on backorder - lead time on request
Edwards
Edwards SIGI-IOI Input/Output Module with Isolator, International, Edwards
Sale price$98.85
Regular price$118.62
Not in stock - available on backorder - lead time on request
Edwards
Edwards SIGI-CT2I 2 Circuit Input Module with Isolator, Edwards
Sale price$78.65
Regular price$94.38
Not in stock - available on backorder - lead time on request
Edwards
Edwards SIGI-CT1I 1 Circuit Input Module with Isolator, Edwards
Sale price$53.55
Regular price$64.26
Not in stock - available on backorder - lead time on request
Edwards
Edwards SIGI-CRI Control Relay with Isolator, Edwards
Sale price$53.45
Regular price$64.14
Not in stock - available on backorder - lead time on request
Edwards
Edwards SIGI-CC2I Dual Input Signal Module with Isolator, Edwards
Sale price$89.75
Regular price$107.70
Not in stock - available on backorder - lead time on request
Edwards
Edwards SIGI-CC2AI Dual Input Signal Module Class a with Isolator, Edwards
Sale price$125.30
Regular price$150.36
Not in stock - available on backorder - lead time on request
Edwards
Edwards SIGI-CC1SI Single Input Signal Module, Synchronization, with Isolator, Edwards
Sale price$74.15
Regular price$88.98
Not in stock - available on backorder - lead time on request