Light box with one black, a two-black-one-red bundle, and a three-white bundle connecting to fixture with one black and one white

electricalinstallationlight-fixturelightingwiring

I swapping a fixture for cosmetic purposes. The old fixture (installed before I was here) has three indistinguishable clear-wrapped wires and a grounding wire.

The wiring in the ceiling is confusing me a lot – I have a bundle of two black and a red, a bundle of three whites, and another lone black wire: attempt at connecting fixture - light always stays on and ignore the switch

Going off of the solution here, I connected white to white, and then black to the black-and-red bundle, and capped the lone black wire. When I kicked power on, the light always stays on, ignoring the switch.

I'm not sure where to go next. I would try just connecting to the red as the link said, but I'm confused how all of this worked with the previous light fixture, and why the two blacks are bundled with the red. This is my first install, so I want to be sure I don't do anything dangerous.

Appreciate any advice!

EDIT 1: adding a picture of previous fixture wiring as requested for clarity: enter image description here One wire was attached to one of each capped bundle in the previous picture.

EDIT 2 adding picture of full previous fixture and closeup of it's make.
full fixture
enter image description here

Best Answer

CAUTION: Verify with a non-contact voltage tester. enter image description here First, look at the wires coming in at the red arrow. This appears to be a pair coming in from the panel, and a second pair, spliced into the box, carrying on to another outlet or light. This is a pretty common scenario. Also, the fact that your incorrectly attached fixture is always on suggests that this is so.

Now look at the yellow arrow. This is a RBW trio. Usually, the black is wired in with the other blacks, down to the switch, and the red comes back as a switched hot.

I believe that the red wire and the single black were swapped at some stage. I think the black should be bundled with the others, and the red should be on its own. (I.E. Convention is that blacks are always hot and red are switched hot for this type of install)

TESTING:
Get a non-contact voltage tester. The black-red bundle should be hot. The red should be hot on one switch position, and no voltage in the other.

Fixing it: If the above tests pass,
Turn the power off at the breaker (and check it!!!)

Separate out the red from the bundle and attach the black to the bundle.
Leave the red as the single wire. (Thus abiding by the convention and not surprising future you.)

Attach the red wire to the fixture black, Attach the fixture white to the white bundle.

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