Getting USB cable through cable gland

[DanielRehak]

Could you stretch the grommet over a USB-C plug? Maybe  with the plastic overmoulding stripped off?

This can be done but you risk stretching the grommet so much it will no longer seal properly. You would need to find a grommet that fulfills following:

1) maximum cable diameter that can fit inside grommet >= maximum USB connector width
2) minimum cable diameter that can fit inside grommet <= USB cable diameter

And there does not exist anything like that.

Max specced dia when used in the gland isn't the same as what you can stretch it to when taken out of the gland.

Ok this is a new one for me. Best next step is to check with ATEX certification organ and Cable gland manufacturers to confirm this would be OK to do so.

[Doctorandus_P]

I would probably cut of the plug, feed the cable through, and then use some non standard connector or soldering inside the box.

But there are also USB connectors made for manual assembly as the picture shown by quadchannel. I had to frown my eyebrow for a moment to see how it works, but the plastic insert is shown rotated 180 degrees. The tin plated tabs is where you solder on the wires inside the plug.

Maybe it is an option to cut of the plug on the other side and then feed through the whole cable?

[mikeselectricstuff]

For production, another option could be to have the inside-box end be a JST or similar, and get a cable with the contact pins crimped but not clicked into the shell, so the crimped ends can pass through the gland, and the shell put on afterwards.
 

[5U4GB]

https://www.lindy.co.uk/usb-c4/200m-fibre-optic-usb-3-0-extender-p9144
...and others

This looks interesting. It is definitely the smallest one i ever saw. But its pretty expensive and mainly it needs 5V 3A power supply which could be solved but would be high effort.

If you don't mind getting it from a crapvendor you can get bump-in-the-stack ones for a lot less, USB connectors at the ends, fibre in between.  You can also get ones with SFP ports so you can add whatever fibre link you want but they cost a bit more.

[_Wim_]

This company make 2 part cable glands that are Ex certified: https://www.roxtec.com/us/our-products/solutions/?filters=49193

We use the non Ex version often at work, nice quality products.

[Doctorandus_P]

Is it an option to replace such glands with some kind of polymerizing caulk? (Silicone or polymer based)

1. Put the cable though.
2. Fill the hole with caulk
3. Let it dry.
4. Mount the nut to put some pressure on the caulk so it seals.

I guess you have to deal with all kinds of regulations when you have to design for an explosion proof environment.

[DanielRehak]

This company make 2 part cable glands that are Ex certified: https://www.roxtec.com/us/our-products/solutions/?filters=49193

We use the non Ex version often at work, nice quality products.

This looks pretty interesting, thank you for the tip. I will contact this company.

[DanielRehak]

Is it an option to replace such glands with some kind of polymerizing caulk? (Silicone or polymer based)

1. Put the cable though.
2. Fill the hole with caulk
3. Let it dry.
4. Mount the nut to put some pressure on the caulk so it seals.

I guess you have to deal with all kinds of regulations when you have to design for an explosion proof environment.

It is, but all such certified devices assume you strip the outer cable coat and fill the caulk only into inner wires, which is good for standard 230V cable but not for USB cable.

[DanielRehak]

I would probably cut of the plug, feed the cable through, and then use some non standard connector or soldering inside the box.

But there are also USB connectors made for manual assembly as the picture shown by quadchannel. I had to frown my eyebrow for a moment to see how it works, but the plastic insert is shown rotated 180 degrees. The tin plated tabs is where you solder on the wires inside the plug.

Maybe it is an option to cut of the plug on the other side and then feed through the whole cable?

Best solution is to buy and solder USB 3.0 header such as this https://ninigi.com/cz/cz/product/ninigi/usb-ieee1394-connectors/usba-w3.0/usba-w3-0/100379/

It works great.