Fixing light fitting to metal cladding

[Sb8389]

Hi guys
Got a job to replace some external lights to an industrial unit.(mostly 150w LED floodlights around 12kg) All lights are currently fixed via nut and bolt with no access from inside as they have now converted to offices so unable utilise existing fixings. What do you guys recommend using to fix some heavy industrial light fittings from experience in this situation.

 

[Charlie_]

What’s behind the cladding?

 

[Sb8389]

no Idea to be honest and no way off really finding out.

 

[westward10]

No way you can somehow utilise the old brackets.

 

[Sb8389]

No way you can somehow utilise the old brackets.

I did think that but the size of the fittings differ quite a bit and the new fittings are grey as opposed to black that is currently there
I did think of something like the grip it fixings that are generally used on plasterboard that Hold a fair bit of weight not sure if they are ok to be used on metal cladding, but something of that design I’m guessing would work.

 

[James]

Get a local fabricator to cut some 300 x 300 flat stainless sheets.
Bolt light from behind using countersunk bolts.
Then fix plate to cladding using lots of self drilling screws.
If you want it really stuck fast then put some silicone behind plate before fixing

 

[Sb8389]

Get a local fabricator to cut some 300 x 300 flat stainless sheets.
Bolt light from behind using countersunk bolts.
Then fix plate to cladding using lots of self drilling screws.
If you want it really stuck fast then put some silicone behind plate before fixing

Not a bad idea

 

[rsgaz]

but something of that design I’m guessing would work.

Jack nuts can do down to 0.1mm material thickness(check the spec first!). And be fitted 'blind'.

If you already have the setting tool for plasterboard brolly fixings, you can use that on these too, just keep a longer bolt with you to 'set' them first. They are supposed to clinch up without that tool, but no chance of it going wrong(i.e. just rotating in the hole) if you do use the tool.

 

[SparkySy]

I have this a lot with agricultural buildings and tend to cut the ends off the old bracket with a grinder and then use a couple of nuts as spacers for the new bracket to sit on top of the existing fixings, then drill the old bracket and tap it or use Tec bolts to hold it up, nice and strong no messing with the cladding bobs yer uncle!
Or if not find a perling that the sheets are attached to and move the fitting to that, they will hold most LED fittings using tec screws.

 

[Mark42]

The answer is 'Rivnuts'!

These are ideal for your application, being fitted into blind holes (no rear access is required), and are available in brass, plated steel, stainless steel, and aluminium. The latter are by far the easiest to set.

Effectively a giant pop-rivet with a central female thread, the most common are in M6, M8 or M10.

I've used hundreds of the things in many applications, and including deliberately wrenching them out to test the strength. They are surprisingly strong: better than Tek Screws in thin sheet.

One point though, it's worth investing in a qualtity setting tool which is about £100-ish. It will last you a lifetime and is much better than the cheap plier-types which often jam up or cause the Rivnut to rotate in the hole.

Links here:

1. Rivnuts

2. Type of Rivnut tool NOT to buy!

3. Better Rivnut tool which actually works

 

[Sb8389]

Thanks for the great ideas guys.

 

[pirate]

I used to use a fair number of pop rivets and rivnuts when attaching fittings to aluminium masts...monel were my choice then, and they worked well on GRP areas where the moulding was closed so access only from the front...didn't rust.

 

[telectrix]

I used to use a fair number of pop rivets and rivnuts when attaching fittings to aluminium masts...monel were my choice then, and they worked well on GRP areas where the moulding was closed so access only from the front...didn't rust.

and i always thought yardarms were attached to masts with ropes and cleats.

 

[pirate]

Yardarms are indeed attached as you say, Tel...but I move with the times, you know...I hold my boom down with a hydraulic vang!

 

[telectrix]

Yardarms are indeed attached as you say, Tel...but I move with the times, you know...I hold my boom down with a hydraulic vang!

i prefer Y-fronts.