HAI water temp sensor/wiring to dock issues.


Working on a project where a customer wants to use the HAI water temp sensor to monitor his lake water temp to activate a de-icer pump on the dock this winter. All the HAI parts are in place to control the pump but we are using air temp now which isn't as reliable in figuring out exactly when the pump needs to run.

The issue I want to bounce off everyone is how to wire to the water sensor. The dock is going to be a 200-300 foot run from the HAI panel. It is obviously exiting the house and then will be located under a rock bed all the way down to the dock. Conduit or trenching is going to be difficult due to the rock/grade of the lot.

What I was thinking about using was getting some 18 gauge underground sprinkler wire due to the multiple conductors and direct bury rating (we may be also installing some additional contacts to monitor boat lift positioning/security). The wire would be placed under the landscaping rock down to the dock. At the dock I'll breakout the wiring in an appropriate waterproof box and then distribute to the water temp/other sensors.

Any issues with voltage drop for this sensor over that length? Or issues with the temp sensor wiring being extended over this distance?

Are there any surge/ground loop issues to be aware of (HAI panel is bonded/grounded per specs) theoretically the dock is at a different ground potential due to being on the water vs. part of the house. I am not aware of any bonding between the house/dock.

Secondary, he also wants to add to his IP camera network with a camera on the dock. Same issues as above but I would have to run Cat-5 down to the dock also and am very concerned about surge/ground loop issues with this. I would assume at a minimum that a cat-5 surge protector would be required at each end of the cable. Currently the customer is using the Panasonic IP cameras in the rest of the home so I would like to stay along this route. Unfortunately the Wireless weatherproof cameras are out of the price range...

Thanks for helping me think through this for the issues that could arise.



Senior Member
Personally, I would look at using something like a Johnson Controls temperature controller for that. They are only about $65 and would do the job self-contained. You could have it trigger an input back to the HAI Omni panel so you can track when it goes on and off. If you did this, I would also add an optically isolated relay back at the house where it attaches to the Omni. I would just be really concerned about having 200-300 feet of direct burial cable attached to the HAI.