Temperature Sensor in Mineral Oil

I recently bought a SNZB-02 and Sonoff IP66 Waterproof Case from www.itead.cc. The intent is to use it as a temperature sensor in my pool. The problem that I think I am going to have though is that the case is going to be full of air (I will have to waterproof the holes in the side as well, as this case is designed for other applications).

My thought, to accommodate for the air buoyancy, was to submerge the sensor in mineral oil. The question I have: It is my understanding that mineral oil is non-conductive. Is that accurate?

Other than bat$h!t crazy, and serving functional purpose other than to entertain my nerdy behavior. Does anyone see any other issues with this?

I know that the humidity sensor is useless at this point, but I don't care as it is going into a sealed box in a pool. The HE is about 30' from the pool (block wall, pool side and water/mineral oil in the way). I have another SNZB-02 in between the HE and pool sensor, so I assume that the real distance will be about 15' repeated.

No, I think that's a great idea. The oil won't hurt electronics and it will conduct heat far better than air and you completely avoid condensation. :+1:

Battery operated ZigBee devices don't repeat. You'll need some sort of line powered device.
Or something like this: @rocketwiz made an Ikea USB repeater into a battery powered device.

Mineral oil to occlude water from entering will not work .... for long. Mineral being a hydrocarbon will attack the plastic and gasket. They will swell and eventually leak. You probably don't want mineral oil in your pool.

Just a thought as I'm typing this..... try filling it with rice. The rice will absorb any water or moisture leaking in and with any luck it will last as long as the battery.
In addition, you could put some rice and the sensor in a small (very small) zip lock bag. Put tape over the opening as the ZIP mechanism does not stop vapor. Then put that in your clear box filled with rice. Should be good for a while.

The above statement regarding the mineral oil is not a guess or theory, I worked for an Automotive fuel systems company and was privy to numerous materials tested in various automotive type fluids.


In addition to what has been mentioned here, you also have the issue of radio waves not easily being transmitted out of water. Especially not 2.4GHz... So you would have to remain with at least part of the device above water.


Will the setup fit into a toy submarine? You could put the antenna through the periscope. Then the buoyancy won't be an issue.

Thank you all for your responses! I didn't even think of the mineral oil eating into the plastic. The rice idea with plastic bag is intriguing.

Yeah. I have a feeling the zigbee signal isn't going to do well in the water. That is the next post to figure out.

Hmm, antenna? I don't think the antenna is external. If I can, I could always use the holes in the box and just run it up the hand rail.

I would recommend you use one of these Temp Sensor

There are several Z-Wave / Zigbee devices that will read one of these. The terminology is
Dallas One Wire Temperature sensor.

hook a ds18b20 (1-wire) to a tasmota itead TH16 should offer you a wired temperature sensor.
The work here is to change the built-in firmware to the Tasmota.

I would be more concerned about it leaking and getting a big blob of mineral oil in my pool. Bulk oil takes forever to remove from a pool. Yuck

Seems pretty strait forward...


I’ve got an Ecolink contact sensor in a small plastic jar sending HE my pool temp. It just Floats inside my pools skimmer box.
The jar has a small weight glued to the bottom to keep it somewhat vertical so the sensor is mostly out of the water.
It’s been working great.

Thank you everyone for your replies! These are all great. I think my favorite is the food saver, but I don't have one... My wife is going to kill me if I buy one just to do this. The container in the skimmer may have to be the way I go.

We have 5 kids so I suggested the food saver as an easy way to pack-up snacks for the kids when we go out. I got the typical shoulder shrug and "whatever you want" and took it as a green light to buy one. I've used it a ton, but not once for food. It's been great for organizing odds and ends of stuff like screws for computer parts, waterproofing sensors, waterproofing phones/keys/wallet when we go to the lake, grouping parts for on-going projects, etc...


Are these the remaining kids after winnowing by the death plug?

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Omg. All those great ideas. I can waterproof everything! I'll start with my kids. It'll be like Ham Solo in Carbonite.

When I was going to respiratory school the it teacher had his students build a pc in a fish tank which they then filled oil. It was cool to look at. Only problem I remember was it slowed spinning fans and they would alarm.

I really don’t think the low powered radio signals will travel out of the water.
Perhaps the pool was ‘above ground’ and had a receiver very close but with an ‘in ground’ pool, I really doubt it’d work.