Load
Review how the Thetford C223-CS connects, how it operates and which installation requirements apply to this model.
Open this example as a new project. Use your own parts and cable lengths to make the plan yours.
The C223-CS has a low-voltage power connection and separate dry contacts for an external pump. The source must supply 3 A, but that capability is not a measured operating or startup draw. Follow the toilet and pump wiring diagrams together.
The C223-CS has a low-voltage power connection and separate dry contacts for an external pump. The source must supply 3 A, but that capability is not a measured operating or startup draw. Follow the toilet and pump wiring diagrams together.
Wiring diagram
Open this example in Crimp to use your own parts and cable lengths. Review the assumptions and installation notes as you adapt the circuit.
Installation notes
Guidance for this model, with sources linked beside the relevant advice.
Verified against the manufacturer's documentation (rev. C220-series installation manual, manufacturer download January 2025), checked 2026-10-01. Manufacturer documentation →
The C223-CS cassette toilet flushes from the vehicle's water system. Do not substitute the C222 variant's integrated flush-water arrangements. The C220 installation manual covers several variants, so follow the columns and drawings marked for the C223-CS throughout. The fresh-water pump is a separate electrical load, even when the toilet operates its control relay.
The electrical drawing, page 23, specifies a 10–15 V supply capable of delivering 3 A. This is a source-capability requirement, not a measured continuous current; the catalog therefore leaves actual operating current and surge unset. Red is supply positive and black is return, shown as positions 5A and 5B in the manual's connector drawing.
The separate grey and purple wires are the external pump-relay contacts: grey NO at 4A and purple COM at 4B. Their maximum contact load is 6 A. They are shown as control terminals in the catalog, not as another battery input, and the model does not simulate the relay's switching. Do not place a pump whose load exceeds that rating directly through these contacts.
The manual identifies the red/black harness as 0.5 mm² and grey/purple as 0.75 mm². Those are the appliance's harness sizes, not an unconditional prescription for a long battery run. The reviewed page does not state an external branch-fuse rating. Protect each installation feed for its conductor and equipment requirements and account separately for the pump's startup and operating demand. The 3 A catalog power-terminal boundary represents the stated supply capability; it is not a verified connector ampacity.
Use the installation sequence and final checks, pages 24–25, to verify access to the waste cassette, the service door, the water connection and the electrical connector. Test flushing, the waste-level indication, leaks and unobstructed removal and insertion of the waste tank. Seal the exterior service-door installation correctly and confirm winter draining for the complete water system. If flushing fails, check supply at the toilet, the pump circuit and relay wiring separately rather than treating the toilet and pump as one load.
Build it out
Add C223-CS to your diagram, then connect your batteries, chargers and loads. Crimp calculates cable sizes and checks the connections as you draw.
Every cable you draw there is sized against ABYC E-11, from the same tables as the reference on this page.
Technical reference
Check the model, ratings and connection points against your own unit before choosing installation hardware.
Check stud sizes, fuse type, run length and how warm the space gets against the gear you actually have before you order.
Catalog connection points, current direction and planning limits. Check the manufacturer's pinout and connector ratings before installation.
+
pos
positive · input
−
neg
negative · input
Pump relay COM
relay-com
signal · input
Pump relay NO
relay-no
signal · input
Method & provenance
Manufacturer specifications describe the equipment. Crimp calculates cable results from the circuit and assumptions you enter.
From the maker
Manufacturer, model, ratings and which terminal does what come from the catalog. A newer revision, or the nameplate on the unit in your hand, can say something different — when it does, the nameplate wins.
ABYC E-11
Sized against ABYC E-11. Boats built to UK or EU rules answer to ISO 13297 — check these figures against it before you build. The run length and the current above are what drive the result. Crimp doesn't know how warm your space gets; draw the cable inside an engine-bay zone on the canvas and it sizes for the heat.
Next step
Open this example as a new project. Add your equipment and cable lengths, then review the sizing and checks for your setup.