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Posted By Topic: When IP rated equipment is required

Dec 27 2018 11:06

Hi all

Staying with family on Xmas day and the power went out and the rain came down.

This resulted in the septic tank system failing and overflowing.

The septic tank system appears to be a 3 chamber system with two submersible pumps. The problem is the junction boxes (for pump and level switches) are below ground level inside the pit. They became submerged and full of water. The boxes are IP rated but not submersible.

Under normal circumstances the boxes would never be submersed.

To get the boxes submersed we need.

* - A lot of rain
* - The power to go out for an extended time
* - A leak / Design problem in the plumbing to allow excess rain into the pit

The question is are non submersible j box allowed inside septic tank system pits?

(PS house is about 15 years old and circuit in not RCD protected)


Dec 27 2018 11:17


Dec 27 2018 12:27

Could just replace with gel filled jb's

Dec 27 2018 12:53

I wondered about gel, would that make it compliant?

Dec 27 2018 16:45

Going by your photos, it would seem that a IP56 box was used for the junction. Following the manufacturers instructions would mean all screw heads covered with silicon and all glands screwed in also with silicon on the thread. And that’s only for IP56 which is not, by definition, submersible. So a gel filled box of higher IP rating would be a sensible solution for this application.

Dec 27 2018 18:34

If its going to get submerged, then IP68 rating is what you need. Most IP68 JBs are filled with a supplied gel once terminations are completed.

Some types of gel-filled boxes are unrepairable, so with this type of box, it often makes sense to use IP68 rated connectors on them, so that if you replace a pump its just a question of fitting a new plug. Bulgin Buccaneers are good. Rapidly gets expensive though.


Dec 27 2018 20:47

Another option to is raise the connection box (and the connections above the maximum level of the tanks under all conditions.
Use of amall pillar as used by electricity distributors means that all connections are easily get at later and in a good position for fault finding if required and very unlikely to wet again.

Dec 27 2018 22:55

Thanks for the tips guys

Some ideas I hadn't thought of or even had knowledge of.

Question: Would the current setup be compliant if installed new now?


Dec 28 2018 18:16

With new septic tank units I have wired up I have always had a wooden post protruding out of the ground around half a meter and all connections are made in a weatherproof enclosure mounted on this post. I have come across several instances of older style septic tank units overflowing and flooding the junction box under the first lid. This seems to happen at christmas more than any other time, probably due to more toilet flushing etc. from guests visiting. Best to get your tanks emptied before christmas rather than trying to arrange to get it done over christmas so the electrician can get the pump going again. Can you extend the cables with links and HD heat shrink, install a post and bring the junction box up on to the post?