The Honeywell Home Sundial Plan Wiring Centre (model 42005748-001) is a universal junction box designed to simplify the wiring of Sundial Plan central heating installations, including C, S and Y plan configurations. With 37 clearly labelled terminals and dedicated connections for each system component, it removes the need to interpret complex wiring diagrams on site.
Built around pre-configured jumper links that match the numbered diagrams in the Honeywell Wiring Guide, the centre supports both basic boilers and those with built-in pump overrun. A fire-retardant ABS enclosure with cable clamps, strain relief on all entries, and a reversible lid and base for top or bottom cable entry make it a fast, tidy hub for new-build and system-upgrade heating installations alike.
37
Labelled Terminals
5A
Max PCB Current @ 230V
2A
On-Board Fuse (+ Spare)
C / S / Y
Plan Compatibility
ABS
Fire-Retardant Enclosure
15A
Rated Wiring Application
Qualified Electrical Installation Required
This wiring centre distributes 230V mains wiring to thermostats, motorised valves and pump controls throughout a central heating system. Installation must be carried out by a qualified electrician or heating engineer in compliance with current UK Wiring Regulations.
Designed Around the Honeywell Wiring Guide
Pre-configured jumper links are numbered to match the diagrams in the Honeywell Home Wiring Guide, so installers simply cut the relevant links per the lid instructions to configure the centre for the specific boiler and zoning layout in use - no separate wiring diagram required.
Confirm System Compatibility
This wiring centre is designed specifically for Sundial Plan C, S and Y systems using motorised valves and Honeywell-compatible thermostats and programmers. Confirm your system layout matches a supported Sundial Plan configuration before use.
One Wire Per Terminal
37 clearly labelled terminals give a single, dedicated connection point for each system component, reducing wiring errors during installation.
Pre-Wired Jumper Links
Pre-configured jumper links corresponding to the numbered Honeywell Wiring Guide diagrams let installers quickly set up the centre for the specific boiler and zoning arrangement.
On-Board Circuit Protection
A 2A on-board fuse, with a spare included, provides built-in circuit protection without needing a separate fused connection unit.
Fire-Retardant, Reversible Enclosure
The fire-retardant ABS housing includes cable clamps and strain relief on all entries, with a reversible lid and base allowing cable entry from the top or bottom depending on installation needs.
Universal 15A-Rated Wiring
Suitable for any 15 amp rated wiring application, giving flexibility across a range of Sundial Plan system layouts and boiler types.
Fast, Compliant Commissioning
Designed to enable compliance with current UK Wiring Regulations and electrical approvals, helping reduce commissioning time on both new-build and upgrade heating installations.
General
Model / MPN
42005748-001
Product Type
Sundial Plan wiring centre / junction box
Compatible Systems
Sundial Plan C, S and Y plan central heating systems
Enclosure Material
Fire-retardant ABS
Electrical
Number of Terminals
37
Terminal Wire Capacity
1.5 mm²
Maximum Current (PCB)
5 A, 230 V, 50 Hz
Fuse Rating
2 A, 230 V, 50 Hz (spare fuse included)
Wiring Application Rating
15 A rated wiring applications
Cable Clamp Capacity
4 x 1.5 mm² twin & earth per clamp (2 clamps)
Mechanical & Environmental
Fixing
3 fixing holes for No. 8 screws
Cable Entry
Reversible lid and base for top or bottom entry
Ambient Temperature Rating
T50
Compliance
Current UK Wiring Regulations
What heating systems is this wiring centre compatible with?
It's designed for Sundial Plan C, S and Y plan central heating systems, supporting basic boilers as well as boilers with built-in pump overrun operation.
Do I need a separate wiring diagram to install this?
No. The wiring centre's pre-configured jumper links are numbered to match the Honeywell Home Wiring Guide, so installers can follow the numbered terminal references directly without a standalone wiring diagram.
What fuse protection does the wiring centre include?
It has a 2A on-board fuse with a spare included, providing built-in circuit protection for the connected heating controls.
Can cables enter from either the top or bottom of the unit?
Yes, the enclosure has a reversible lid and base, allowing cable entry from the top or bottom depending on the installation's routing requirements.
How many terminals does the wiring centre have?
There are 37 clearly labelled terminals, each accepting a single wire per connection, which helps ensure accurate wiring during installation.
BTU & WATT Calculator
Room Dimensions
Room Type
Living Room
Bedroom
Kitchen
Bathroom
Conservatory
Hallway
Glazing Type
Single Glazed
Double Glazed
Triple Glazed
External Walls
0 Wall
1 Wall
2 Walls
3 Walls
4 Walls
Insulation Level
Poor
Average
Good (New Build)
Required Heating
0
Watts
0
BTUs
Documentation
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