How should I mount this ceiling light fixture?

Question

I have a fairly heavy (a few kg) hanging lamp which came with this ceiling mount (and no instructions):

So, to mount it, I can remove the bracket from the cover, screw it to the ceiling, put the cover back over the bracket, and screw the bolts back in from the outside to attach them. But there's a problem.

On the inside of each bolt is a split washer and nut. How can I get the nut back on the bolt once I have the cover back on and flush with the ceiling? Apart from the central hole for the cable, there are three additional holes in the cover. These are unfortunately useless for getting at the nuts on the inside: they attach to three anchors for steel wires which support the weight of the lampshade, so they will necessarily be blocked when I put the cover on, and in any case don't line up with the bracket:

The bracket itself is threaded, so the nuts don't seem to be strictly necessary. On the other hand, since they came with the fitting and it needs to hold a fair amount of weight, I'd prefer to have them in place if possible. Am I missing something here?

Answer 1

Given the bracket itself is threaded, assuming the screws hold firmly (eg: are correctly sized for the threads in the bracket, and the bracket is not stripped), I would install it without the nuts.

The screws are transferring the shear load from the white cover to the metal bracket, which in turn is held to the ceiling box, which in turn (as other have pointed out) is hopefully firmly attached to structure. Even if you could somehow get those nuts on, they would not be supporting any load -- they would just be preventing the screws from pulling out.

From your pictures, the bracket looks of sufficient depth that there a couple complete threads, and the screws extend quite far past the bracket (meaning it would take several full rotations to get them out, which is not something that will happen to a light just hanging from the ceiling).

So:

1. Verify the box can hold the weight
2. Attach the bracket to the box
3. Wire the light
4. Screw the fixture cover to the bracket

Answer 2

You have holes in the cover plate - they should line up with the mounting bracket so you need not separate the mounting bracket from the cover plate. You simply use a screw drive and insert in those holes to tighten the screws. Hopefully the electrical box you have in your ceiling is properly mounted to a joist in order to support the weight.

Normally if the electrical box was installed with a ceiling fan in mind - you can easily mount your lamp - given you used the term Kilogram - I assume you are not in the USA - make sure your electrical box will properly support the weight of the lamp. Here in the USA I usually add a 2x4 across the joists and fasten the box to the support.