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Ultima Switch 20AMP 12/24V

The solid-state electronic automatic switch Ultima Switch uses the patented Mirus field effect detector cells producing micro-electrical fields that detect disruptions caused by water and fluids. Detector cells are sealed and are never in contact with water, will not rust and are not affected by oil or foreign debris.

  • Limited 3-Year Warranty
  • No moving parts, totally sealed solid-state electronics and field detectors
  • Environmentally sensitive; no mercury
  • No exposed sensors eliminate corrosion possibilities
  • Activates at a 50 mm (2") fluid level and deactivates at a 20 mm (¾") fluid level
  • A three-second delay prevents false starts from water sloshing in the bilge
  • Ultima Switch is rated to handle pumps up to 20A at 12V or 10A at 24V.



Part No.Part No. USADescriptionMax Amp.
34-3630336303Ultima Switch Electronic Automatic Switch 12/24V




The automatic switch protects electrically operated
pumps and gives fully automatic operation.
The switch is made of corrosion-resistant materials.


 SPX FLOW Johnson Pump submersible bilge pumps have a T-slot on the housing 
or mounting bracket. You may push the switch into place on the pump.
If you wish, a small drop of water-proof adhesive will lock the switch on the T.

Screws are recommended for fastening the switch only if your pump is not equipped

with a T-mount should always be installed in parallel to the keel with the floating

body directed aft.



The Ultima Switch is a highly reliable solid-state switch which uses no mechanical parts or toxic mercury to sense water level and automatically controls a 12V DC or 24V DC bilge pump. The switch activates the pump when the water level reaches 2” or more and turns off the pump when the water level reaches below ¾”. The Ultima Switch automatically adjusts between a 12V DC bilge pump or a 24V DC pump without any adjustments necessary


Installation Location:

1. Mount the Ultima Switch in a vertical position (Mount holes towards the bottom of the vessel) and close to the pump such that the water level is equal on both pump and the Ultima Switch.

2. Do not mount the Ultima Switch directly to the hull of the boat. Use a mounting block of at least ¾” thick marine plywood epoxied to the hull of the boat to fasten the Ultima Switch.

3. The bottom of the Ultima Switch can be mounted higher but never lower than the base of the pump. Note: If you are mounting the Ultima Switch on the side of the boat, make sure you fasten the Ultima Switch using the side posts and observe the same mounting instructions as you would installing the Ultima Switch in a vertical position.



1. Mark pilot holes in the base of the Ultima Switch by using the Ultima Switch holes.

2. To avoid drilling through the hull of the vessel, set your drill to the appropriate depth for the pilot holes.

3. Fasten the Ultima Switch directly to the block using #8 x 5/8” long stainless steel screws (not supplied).



1. Connect the remote manual switch and inline fuse between the battery and the Ultima Switch.

2. The wiring connections should be made with water-resist