XPS 13 9370, which USB-C ports can I plug the A/C adapter into?

Thanks for that explanation! I had some basic understanding of PD but only related to phones. I was very hesitant to just try it on this expensive laptop but you made a really good point.

Just tried the other left USB-C port. No explosion. Looks normal.

And the one I wanted to use ... right side... No explosion. 

I can't believe I have had this thing for six months and I've been maneuvering things so I only use the left side.

Thanks!!!

@PaulQ99  happy to help!  And if you're now wondering why only one of those ports has a power plug icon next to it, having worked in various IT capacities in my career, including end user support, I honestly think it's a proactive measure against support calls.  If Dell hadn't marked any of the ports that way, then I guarantee you people would have called them asking which port they were supposed to use and chastising them for not making that clear.  And if they had gone the other way and marked ALL of the ports with that icon, then in addition to that probably looking awkward and possibly creating issues around space between ports for the marking itself, there would be at least some users who would call Dell wondering why their system only came with one power adapter if they're supposed to have one plugged into all of those ports simultaneously in order to get maximum performance.  You might think that nobody would have ever thought that, but I can assure you from experience that some people would have.  Working in IT really gives you an appreciation for the saying that when you try to make something more foolproof, the world responds by making a better fool. :)

Makes sense. Although the power plug icon is microscopic, I do admit it's what kept me from trying any others.

So, we have the thunderbolt port on the right which can also act as a PD port? So that port can basically do everything?

They can all be used for data transmission, correct? (e.g. flash drives)

The two left ports also have a lightning bolt next to each. I took that to mean I can use them to charge other things when the laptop is asleep (e.g., my phone). I never have a need. Is that what the symbol means?

(I'm trying to get all my XPS 13 USB-C features straight here)

@PaulQ99  one more thing.  Looking at the XPS 13 9370's Setup and Specifications document (available here, along with some other documentation you might find useful some day), it specifies that all of the ports support two-way USB Power Delivery.  But it also notes that the power delivery outputs are different.  The left ports can provide up to 15W to attached accessories (5V at 3A), but the right port can only provide up to 7.5W.  That has nothing to do with the wattage they can accept via USB PD, but if you ever need to use high-powered peripherals, you might want to keep that in mind.  For example, the Dell DA300 "mini-dock dongle" has USB ports that work differently based on how much power the DA300 itself is receiving from the system. Enjoy!

You posted your follow-up as I posted mine. You answered most of what I asked.

... and I was wrong. The right-side port is the most basic of the three. The thunderbolt icon on the left ones means... well... thunderbolt support. 

Thanks for that link. It has loads of information!

@PaulQ99  as you've found, the lightning bolt icons on the left ports indicate Thunderbolt 3 support there.  TB3 is a superset of the USB-C feature set, so yes those ports can be used for regular USB traffic as well, just like the port on the right.  And apparently all of them also support being used for video output to a display through things like USB-C docking stations, USB-C to HDMI/DisplayPort adapters/cables, etc.  I'm not sure what icon you were looking at when you first mentioned a suspected Thunderbolt icon on the right port, though.  A quick Google Images search shows a DisplayPort icon on the right port, which indicates video output capability.  (That capability is mandatory for Thunderbolt 3 ports, so adding the DisplayPort marking on the left ports would be redundant, although there are plenty of systems with USB-C ports that support video output but don't have any marking to indicate that.)

As for the documentation, you're very welcome for the link.  Dell is pretty good about posting useful documentation to support.dell.com, especially the Service Manuals that include step-by-step instructions and diagrams for removing and installing every component of the system, although that's admittedly a bit less useful on the XPS 13 9370 because most of the components you might want to upgrade (WiFi, SSD, RAM) are all soldered onto the motherboard in that system.  Apple's been doing this for a while because it allows their systems to be thinner and lighter, but the unfortunate side effect is that it means you have to order whatever you expect to need over the lifetime of your system upfront rather than being able to upgrade later (and likely at a lower cost) if/when the need arises down the road.