How to seal a conduit with an underground cable?

I would press in a suitable sealing plug (e.g. Kaiser sealing plug ECON) and then cover it again with a heat shrink tube. The sealing plug achieves airtightness and with a correspondingly thick-walled heat shrink tube also offers some mechanical protection for the end of the empty conduit.

What speaks against direct installation without an empty conduit? After all, the underground cable is made for that.

shouldn't the cable be laid in an empty conduit for additional protection and so that the cable can be replaced in the future

with the Kaiser sealing plug, can the empty conduit be sealed waterproof?

How does one get the cable through the plug?

@Michilo shouldn't the cable be laid in an empty conduit for additional protection and so that the cable can be replaced in the future

A lot of theory. 1. The underground cable does not require additional protection. If you ever dig, the conduit won't help either. 2. Replacement usually never occurs.

so you would recommend laying the underground cable without a conduit?

That is more for protection against animals, or a spade

@nordanney so you would recommend laying the underground cable without a conduit?

Yep. I've been doing that for 30 years without problems (in my own houses)

Can the Kaiser sealing plug waterproofly seal the empty conduit?
How do you get the cable through the plug?

I don’t know if it is waterproof. It was developed for airtightness. You can simply pierce the membrane with the cable.

That is more protection against animals or shovels

A conduit or protective pipe (it’s no longer empty) doesn’t help against shovels either. Just take the underground cable as it is. If you are worried about the future, take a 5x1.5/5x2.5 right away and end it in a Friedl junction box. You can then connect everything else there.