Captive safety bonds for fixtures

[Stuart91]

The possible severity of having a Source Four land on your head from, say, 30ft is also Single Death as well.

 

The likelihood will be a good bit lower, however.

[top-cat]

To be honest, if your risk assessment sees the ceiling falling down as a likely enough event that it justifies putting safety bonds on all the lights... then I would say your risk assessment has also identified that your theatre is not safe enough to put on shows at all...

 

 

[Maybe next time it won't be a ceiling, but something else very improbable - maybe safeties will help, maybe they won't, but I'd rather have them than not.

 

Away from the "moving bars on a tight stage" scenario, the type of event that will dislodge a G-clamp is very rare, and hence hard to foresee. But the provision of safety bonds, and the additional seconds it takes to put one in place, means that the obvious argument would be "why didn't you use them?". Whilst I can sympathise with many of top-cat's arguments against using them, I would not relish the task of justifying my decision after something, no matter how improbable has gone wrong.

 

 

I'm not so much arguing for 'not using them' - if you've one there, putting it on the fixture is not going to do you any harm. But that said, under the same logic, you could put 2 on it. That won't do any harm either. And the likelihood of it needing to rely on the second safety bond (IE very low) is not really any higher than the likelihood of it having to rely on the first.

 

This discussion came about because somebody said "my safety bonds are going walkies from my fixtures". My suggestion was "how about not using safety bonds, and instead using a clamp design with less likelihood of being knocked off the bar" . It's a perfectly sensible suggestion, and one which I stand by. A half coupler when done up properly has a very good grip on the bar or truss and since they're rated at 750kg SWL are far over engineered for the fixtures we're likely to hang on them. I cannot think of any occurrence within a performance environment where a properly applied half coupler could accidentally come undone and open fully allowing the fixture to drop. I think somebody hit the nail on the head earlier when they said it was one of those things we do but we don't know why we do it. If you risk assessed the necessity for safety bonds rather than using the "why not?" principle, you would most likely come to the conclusion that you didn't need to use them.

 

As for the car seat belt thing, the other reason it's a bad example is that wearing a seatbelt is your only option for mitigating the risk further. You have no capability to make your car more impact resistant, and whilst you can make your own driving safer, you cannot make other peoples' any safer; so driving with a seatbelt on is the only thing you can do to control the risk, since it cannot be eliminated. (Remember ERIC - Eliminate, Reduce, Isolate, Control). Using a better hanging device would come under REDUCE, since you are reducing the chance of the fixture falling in the first place. A safety bond would come under Control, since it's not preventing the fixture falling, it's limiting how far. And reducing a risk will always be the preferable route than simply controlling it.

[Stuart91]

Again, I'm not really disagreeing here - safeties have become just one of these things that we do. Indeed, hopefully a discussion like we've all had here will help make people think about why they are doing what they do.

 

The main problem is that lots of people are under the impression that "no safeties = cowboy operators" and aren't going to listen to any argument against them, no matter how sensible and well-reasoned.

[dbuckley]

Indeedy Stuart; no safety is probably the number one cause of getting ones work listed on dodgy techs.

 

I've never really thought about this, and have always fitted safeties as somewhere along the line, I acquired the knowledge it is the right thing to do. However, if a fixture is attached with two somethings, I often don't fit a safety as there is no single point of failure, which is what I believe I've always been guarding against.

 

Thing is though, should anything happen, an anything that a safety may have reduced or eliminated (or possibly just changed) the hazard, then one would have some explaining to do.

 

Here in NZ the book says we "should" use safety chains(!). If one doesn't then one is going against industry best practice, and in the event of an incident, one would have to explain why one didn't follow the book.

 

And no one in christchurch though that buildings failing was a likely risk, till it the earthquakes...

[ianl]

I've seen a sil30 fall onto its safety when the hook clamp broke

 

The safety broke too

 

The light was caught by the silicon secondry safety with the 15a connection

 

 

Years ago I read in some official document that the reason for using safeties on stage lights was because of the repetednes of the instalation there was a higher chance of us getting it wrong over a permanent instal that would be done once and therefore more likely done correctly

 

Its amazing how little grasp of reality some "important" people have

 

I remember a conversation recently alomg the lines of: you stage guys always work safely, these site rules are mainly here for the idiot builders

 

 

On the subject of losing safetys, I have had a number of crew over the years that think the correct way to take a light down is to go up ladder, un hook safety wire and throw on floor, carry or rope light down, unbolt hanger, throw handful of bolts, nuts and washers on floor, repeat till done.

Only last week someone taking 12 lights down threw 11 safeties from the roof, afterwards I went round collecting them but only found 9, I then had to find the lights to put them back on

 

Equally I dont like captive safeties, a number of times I,ve seen them rigged such that they don,t actually go through the yoke or safety point

[Andrew C]

We had this discussion on the old ABTT forum, donkeys' years ago.

 

I asked the question then; "Has anyone actually SEEN a lantern fall onto a chain?" I think one person had, when a flybar ripped a lantern off on the way up. But yes, I still use them, and try to keep the bonds tied to the lanterns. I work with school kids (and some numpties); if the bond is there, it will probably be used. If it isn't...

[Seano]

I asked the question then; "Has anyone actually SEEN a lantern fall onto a chain?" I think one person had, when a flybar ripped a lantern off on the way up.

 

I've seen that happen. Just the once.

[top-cat]

Out of interest, for anyone who has witnessed a fixture falling down (be it, colliding with another fly bar, with a tallescope, just randomly, whatever)... can you remember what it was that had failed? Was it the hook clamp itself (IE, coming free of the bar, or somehow breaking), the yoke coming free of the hook, the yoke coming free of the fixture, etc?

 

In my opinion, on many if not most fixtures, the least substantially engineered element of that chain is the yoke-body fixing. And yet it is this element which is not protected against in the frequent occurrence that the technician loops the safety through the yoke and over the bar. This only protects against failure of the hook clamp itself, or it's connection with the yoke.

[sleah]

In my opinion, on many if not most fixtures, the least substantially engineered element of that chain is the yoke-body fixing. And yet it is this element which is not protected against in the frequent occurrence that the technician loops the safety through the yoke and over the bar. This only protects against failure of the hook clamp itself, or it's connection with the yoke.

The saving grace is that it has a kind of built-in secondary, in that the yoke usually attaches on either side of the fixture, the chances of both sides failing at the same time are slim... there are of course exceptions, such a single sided yoke - in which case the common method of safety bond round the yoke would be pretty pointless anyway.

[alistermorton]

The saving grace is that it has a kind of built-in secondary, in that the yoke usually attaches on either side of the fixture, the chances of both sides failing at the same time are slim... there are of course exceptions, such a single sided yoke - in which case the common method of safety bond round the yoke would be pretty pointless anyway.

 

Good point - I've often wondered what the best way to safety something like a minim is. I've ended up looping the safety around the single sided fixing, in a sort of knot, but that strikes me as a bodge.I suppose really we should drill the fixing and attach a ring to it for the safety to attach to.

 

 

 

[ianl]

The hook clamp peeled open and returned to the flat piece of metal it started life as

[J Pearce]

Do minims not have the same safety eyes on the back as the preludes? It slotted into one of the channels in the extrusion as far as I remember.

[ianl]

No

 

Do minims not have the same safety eyes on the back as the preludes? It slotted into one of the channels in the extrusion as far as I remember.

[Stuart91]

My hook clamp tale is as follows:

 

There's a Miniscan HPE rigged on a truss. There is a safety bond on it, but for whatever reason the clamp itself is not fully tightened.

 

Later on, someone is trying to troubleshoot some DMX niggles. He replaces the DMX input cable, and the upward pressure of the new cable being inserted is enough to lift the clamp a little. Not enough to actually get the clamp free of the truss, but it gave him quite a fright and we were all quite glad that the safety bond was in place.

 

I guess this counts as a "near miss". It was approx 7yrs ago, and nothing similar has reoccurred since.

[top-cat]

The hook clamp peeled open and returned to the flat piece of metal it started life as

 

Jesus! Was it just a very poorly made hook clamp, or were you hanging a car on it? No way a standard conventional fixture could bend a decent quality hook clamp.