I went to install a Qubino relay behind a switch and based on all the wiring diagrams I’ve seen, it looks like this circuit is using the white wire for hot and the black wire for neutral.
If I use a non-contact electrical tester and find that to be true, should I just wire it using white for line/load and black for neutral?
I’m not sure where those other wires are going so I’m really not up for trying to rewire everything the correct way.
Thanks for any guidance you can provide.
US code does not mandate wire color in most circumstances. I’ve seen a switch box with five black wires and none of them were the load. I’ve seen a switch box with three white wires and none of them were neutral. It happens, especially if you get towards the end of the day and there’s only one spool of wire left in the toolbox. 
Just ignore the colors and map the circuits fully so you know what’s going on before proceeding further. Oh, and tag each wire and take before pictures in case you need to put everything back. You can use electrical tape to create striping if you want to identify the individual wires.
Other than that, I’ll leave any discussion of specific wiring issues in the photos to people who know what they’re doing in that regard. 
( I’m a network engineer, not an electrician.)
Agree with everything @JDRoberts said, but also wanted to add that IME it’s more likely wired to switch the neutral leg of the circuit than wired with non-customary color coding. And while a non contact tester might help you figure out what’s what, it’s far from fool proof. A contact tester would be much more helpful/useful in figuring out what’s what.
A non-contact tester is not worth a dime in close proximity to other wires.
I’ll add whatever amateur hour loser did that work should be flogged.
At the least, you need to pull everything, add 2-screw (wire clamp) connectors where all those unprotected wires enter.
Take a look at those green wire nuts also. If they have a hole, in the end, they are for ground.
As previously stated, probably a switch leg and not hot in the box.
This is wrong in several ways and IMO also a safety hazard that is EASY to fix.
Standard coloring of residential conductors is white for neutral and black for hot. There are some exceptions but I doubt they apply to the circuit in the picture.
See: Design and installation conventions
Issues I see:
Assuming the house is wired properly, it is not acceptable to switch the neutral wire (white). While it obviously works as it breaks the circuit, it is a safety hazard as whatever it is switching, is still hot and can therefore shock someone. Regardless of how unlikely the hazard may be, it still is. “Honey, turn the light off so I can replace this broken bulb” and Honey may become a widow.
Wires enter the junction box through bare knockouts. Regardless of actual risk, it is cheap to fix this and make it to code. There are several different options but the one I would use is this:
This is another option but it is not as good in making sure a wire doesn’t get yanked out of the box for whatever reason. If you use these, they are inserted in the knockout from the outside so that the tabs dig into the jacket not allowing the cable to be pulled out.
Either way, make sure you get the right size for the hole.
The circuit here looks simple. The wires in the gray cables appear to be 12 AWG wire as they seem larger than the wires in the white cable (outer jacket). Typically a white cable (Romex) is 14 AWG and a yellow one is 12 AWG (so I am not sure why this one is gray… maybe it was made for outdoor use).
To fix this mess:
Cut power to this circuit (or all the house if you prefer).
Straighten out all wires and disconnect all blacks and whites from each-other. (Remove nuts, and untwist all wires). When done you should have 3 loose white wires and 3 loose black wires. Put a wire nut on each wire for safety to ensure they DO NOT TOUCH anything.
Turn power back on. Find what wire is hot using a non contact voltage tester. I have never used one as I typically only use contact testers but it is cheaper and likely safer for you if you are not used to doing electrical work. I am expecting you would find a single black wire as hot. If proximity of wires is causing bad readings then you will need to disconnect all wires (including grounds) and pull them out of the box which is something you need to do anyway to install the cable restraints. Once you know which wire is hot, go turn the power back off.
ASSUMPTION: You found that one of the gray cables has a hot black. That is your supply cable from the breaker, and the other two are going to outlets or lights.
Disconnect ground cables as well.
Ensure there is no power on any wires!!!
Remove all nuts. Pull cables out from metal box (careful not to damage them on sharp knockouts)
Install your chosen cable restraint, and run 1 or 2 cables max through each restraint. Tighten the restraints without causing damage. It just needs to prevent the cables from being loose or “yankable”.
Not knowing your level of electrical expertise, this video shows how to properly twist solid wires together. (Sorry if basic, I just want to be sure):
Twist your 4 bare ground wires together (the 4rth wire is that green wire with a screw at the end). If you don’t want to use that method, just use a 10 inch bare wire that will be screwed to the green screw on the switch. The grounded switch frame will ground the box. I am not sure whether NEC requires wiring to the box AND the switch… so I would prefer the box grounding as it is more important. Install a properly sized nut. I believe color does not matter as long as it is of the proper size. I use green to be sure… just in case there is a rule. I believe the ground wire should be the larger size of the two, so likely 12 AWG)
Twist all the White wires together. Install a properly sized nut. Make sure your connection is solid.
Prepare a 10 inch black wire (14 AWG should be fine since you will be powering the white romex circuit).
Twist the 2 blacks from the GRAY cables along with this 10 in black wire you just prepared. Install a nut and make sure the connection is solid.
You should be left with a black wire from the white cable that is not connected, and a black wire from the black wire bundle that is not connected. Each one of these goes to the switch. Wrap the wire around the screws in the same direction you use to tighten the screw.
Check your work…
All cables entering the box through cable restraints. Cables are not super tight but not loose. Tugging on the cables will not move them.
All ground wires are connected together, and to the box/switch grounding point.
(See assumption) Two blacks from GRAY cables and a wire going to the switch are twisted together.
All white wires are twisted together.
The black wire from the WHITE cable is connected to the switch.
Sorry for terrible drawing:
DISCLAIMER: I am not a licensed electrician but I put a lot of research into this and have always exceeded towards safety rather than easy or cost savings.
Also, you might have issues installing the Cubino inside the metal box. It may work but the range will likely be reduced quite a bit.
I use some of your DTHs, so, as a thank you for sharing your work, I’d be glad to go over some of this over the phone if it helps you. PM me for the number in case you want to do so.
PS: Just noticed… get rid of the white stranded wire. Use the proper solid wire for this application. Home Depot (since all the links I provided are from them) should be able to sell you a few feet of 14/2 Romex cable, if not this may be an alternative (but only use it when the circuit is 14 AWG, otherwise you need the Yellow jacket one for 12 AWG - yourswitch is controlling something powered via a white jacket cable which should be 14 AWG):
As far as range on the Qubino, they are usually fine as long as the switch plate is RF permeable and either the hub or a repeater is in the same room along the transmission path. Those micros are designed to be put into switch boxes, including metal ones, and usually work fine as long as you follow the installation instructions in the user guide.
Now if you use a metal face plate as the cover, all bets are off.
The pictures show a metal box and a metal cover. The switch is of the toggle kind so the opening is minimal. However, I have an energy meter inside an electrical panel outside and it still magically manages to talk to a node in the nearby garage. It’s just a gamble. Doesn’t the Cubino have a wire antenna? If so you could have it poke through a hole in the box…
It does, although the instructions say to keep it vertical.
I missed the metal cover in the pictures, but you know, it may still work well enough to at least get signal to another nearby repeater. These things are always trial and error if you do have a problem. If you don’t have a problem, you don’t have to worry about it. 
Thanks for all of the information, I really appreciate it.
This is a switch in my sister’s garage so it’s something I’ll have to tackle some other weekend, but at least now I know how to map everything out and correct it.
