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Hanging bars from rafters


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Whilst I've been around a bit, I just helped out at a new venue to me, a community theatre where I helped hanging lights.

 

I was a "little" concerned that the way the bars are hung is from self-tapping eye hook bolts into the wooden rafters using unrated chain

 

To make matters worse, whilst the end of each chain was attached to an individual eye hook, the chain itself was only wrapped around the bar not fixed to it.

 

To take it further there were only two chains per bar (I would of expected to see something in the middle for all but the shortest bar).

 

 

How should they be doing it, given that they don't have access to the top of each rafter (as the roof sits on it) and they have a need to reconfigure the bars for each show.

 

My initial thoughts were to

 

* see if there were a bracket that would surround the rafter on all three sides and would take a bolt through it (and the rafter)

* replace the chain with rated steel rope

* find something to couple the bar to the rope

* suspend each bar from at least three (evenly spaced) places

 

My other challenge will be (as a new member) to get them to spend the money for something that is working fine for them.

 

Or...are my concerns unfounded? (I live by the motto "for a bad thing to happen just requires good men to do nothing")

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This will be one of those can of worms that you wished you had not opened, as soon as you start to look at making changes a load of other things will become apparent and the costs involved will rise.

 

 

One of the first thing to establish is if the beams are sufficient to take the load, they may look big and chunky but without knowing the span and the load on the roof, only by using span tables and working out the loads can you know that capacity of the beams, and that will usually require a structural engineer.

 

If the beams are sufficient then there are a number of options available in the way of brackets, and depending on the loads and the allowable direction of loading on the beams the screw eye option may be OK.

 

You would be surprised the amount of things hung on unrated chain most light fittings in commercial buildings are hung from non welded jack chain, and how that passes I have no idea, but again it will be down to the load being hung. After speaking to an engineer they will be able to tell you what you can hang and from there you can talk to a supplier to give you the options available and a budget cost. There is no point in getting a totally flexible solution with adjustable pre-wired bars if all you can put up is a couple of fixed spot fixtures.

 

To aid you in the getting them to spend money, you will need to point out their liability should something happen, and that ignorance to the raft of regulations that will be out there is no excuse in court, and just because its "the way they always have done it" dose not mean it's still OK, talk to an engineer, find out how much you can hang, then look at what they can afford.

 

Having said all that, I would go with bolt through brackets, rated chain droppers and barrel clamps, all of which you should be able to find from someone like flints.co.uk. If you wanted something to give you fixed bars, then something similar to a boom arm may be something to look at, bolted to the beam and the tube clamped in the other end.

 

 

 

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chain wrap to hold up bars was also a fairly "standard" installation method in the 70's/80's - walk in to a school hall / village hall / civic hall and you'll probably find that most of the bars in there are still held up using this method. It's also still a fairly common method in the USA for attaching fly-bars to the lift lines so whilst it's not to modern expectations & standards it would probably still be allowed under "grandfather rights" and isn't as inherently crazy or unsuitable as you might immediately think.

 

As Ontop points out you do need to be careful here of the can of worms you're opening - look to closely and you will find dozens of things like this which don't meet modern expectations and before you know it you'll be forcing them to spend thousands of pounds..... to end up with something that to them is no different to the set-up they have now and have been using for decades. If the bars really concern you then installing a couple of well thought out seconds/safeties so that should the old rigging fail then a more serious incident is prevented would be very cost-effective, minimally invasive and a more proportionate acceptable response to potential risk.

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Have I woken up in a parallel universe? Are we really advising that hanging a lighting bar from screws eyes might be OK? Or that wrapping chain around a bar is acceptable because that's how it was done in the olden days? How would the chain be attached to the hanging point and/or itself? Can't use a shackle because long-link chain is specifically not allowed (we had to get special dispensation to use STAC chain).
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Have I woken up in a parallel universe? Are we really advising that hanging a lighting bar from screws eyes might be OK?

 

No, I think we are advising that an existing rig like that does not necessarily need to be scrapped and reinstalled. I don't think anyone is saying that it's the right way to do it.

 

I have visited plenty of village halls and community spaces and stuff like this is everywhere. In fact this sounds quite robust compared to some of the bodgery there is out there.

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If this is a new install then no those practices wouldn't be acceptable - but it seems likely that this is an older/historic venue and so the bar was installed in line with the standard practices of the day. The method isn't inherently dangerous (as the 40+ year installs all over the country show) nor is it especially unusual (I've just facebooked a couple of american colleagues who confirm that chain wrapped fly bars are "normal" ) so if the use today is in line with the original specification and the equipment (however unconventional) is inspected periodically and isn't showing any signs of duress or failure then there isn't a pressing need to change it. Since we are talking about a small community theatre then opening the can of worms that comes with insisting that perfectly serviceable equipment be scrapped and replaced with modern code equipment will kick off a chain of similar works across the entire building at best lead to massive resentment and more likely lead to the bankruptcy of the group because of the cost being several times the turn-over of the venue.

 

Step in to any "classic" theatre and I can assure you the many tonnes of ornate plaster work above your head are held up with nothing more than 100 year old string and paste. That was the acceptable, normal method of holding ceilings up when the theatre was built and clearly it is a suitable solution since generally the roof has stayed up for a century (with one high-profile exception) whereas if you were building an identical theatre today you would have to hold the ceiling up with modern metal ties. There H&S executive doesn't expect the thousands of theatres and cinema with string roofs to rip out the old supports and replace them all to modern standards, rather they accept that an active program of inspection and the inclusion of appropriate secondaries is a proportionate way to deal with the potential risks of outdated work practices.

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If the bars really concern you then installing a couple of well thought out seconds/safeties so that should the old rigging fail then a more serious incident is prevented would be very cost-effective, minimally invasive and a more proportionate acceptable response to potential risk.

 

Given the situation the OP describes, I don't see how an adequate secondary would be either cheaper or easier to organise than sorting out the primary rigging in the first place. It would be the same kit that could be used to replace existing rigging used to back it up instead.

 

(we had to get special dispensation to use STAC chain).

 

There's no "special dispensation" for STAC as I understand it. Contrary to what many believed it was never "illegal" to use it above the hoist, so none required. Strictly speaking it still shouldn't be used below the hoist so no special dispensation there either. (Hardly a concern if it's used correctly though.)

 

The point of the prohibition in the Machinery Directive against long link chain as a rigging accessory is to prevent such a chain from being used as a sling (ie: wrapped around something), and it's also perfectly clear (hopefully) that it's not acceptable practice to use STAC that way in spite of it's mighty strength. Never was.

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(we had to get special dispensation to use STAC chain).

 

There's no "special dispensation" for STAC as I understand it. Contrary to what many believed it was never "illegal" to use it above the hoist, so none required. Strictly speaking it still shouldn't be used below the hoist so no special dispensation there either. (Hardly a concern if it's used correctly though.)

 

The point of the prohibition in the Machinery Directive against long link chain as a rigging accessory is to prevent such a chain from being used as a sling (ie: wrapped around something), and it's also perfectly clear (hopefully) that it's not acceptable practice to use STAC that way in spite of it's mighty strength. Never was.

 

Fair enough, I simplified for brevity. It was a clarification of the legal position rather than 'special dispensation' but it did take a while to be published.

 

I wasn't suggesting that STAC chain could be wrapped around a bar. I was trying to make the point that using chain that accommodates a shackle pin is not as simple as it was once upon a time. I can see how my hurried response is not clear.

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Given the situation the OP describes, I don't see how an adequate secondary would be either cheaper or easier to organise than sorting out the primary rigging in the first place. It would be the same kit that could be used to replace existing rigging used to back it up instead.

obviously replacing everything with modern standard kit is always the optimum solution.

However if the OP removes/replaces the existing rigging then he would be obligated to undertake the new installation in line with current regulations and would have to produce a certain amount of paperwork (some sort of structural engineers report confirming the loading of the joist he's now using in a different configuration to its original installation, some sort of load testing/declaration for the newly rigged bar) to comply with that and to comply with the building's insurance and possibly even building regulations. So replacing the existing fixings requires not only the physical job but also the cost of an outside expert but also an inch or so of paperwork documenting the changes and confirming compliance with new regulations. This would also almost certainly trigger someone (council, insurers, etc) scrutinising the venue much more closely and asking the questions "if you're so worried why aren't you replacing all the other rigging in the building" and "why don't you replace all the electrical wiring with current standard kit" - obviously these are both great goals to aspire to but I'm quite sure that a small community venue doesn't have the tens of thousands of pounds it will cost so will then be forced to consider closing down because they are now instantly operating against the advice or requirements of their insurers or local authority simply because the question has been asked and apparent panic works undertaken

However adding a secondary to the bar could be done in an hour or so with off the shelf equipment, a "reasonable person" could make assessments as to the appropriate joist (or joists) to attach to with a response that meets all the H&S requirements for a proportionate response to possible risks. Everything is safer, the worm can stays firmly shut, risk has been significantly reduced and the OP also has something to reference and use as leverage for instigating a more manageable long-term program of equipment renewal.

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Yet again people are over-thinking.

 

If the venue decided to install air conditioning then the installer would turn up, look at the timbers and go ahead and screw their equipment to them using chunky screws. Would they get in a structural engineer? No, of course not. Are people being killed the length and breadth of the UK by falling air conditioners? No, of course they aren't.

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However adding a secondary to the bar could be done in an hour or so with off the shelf equipment, a "reasonable person" could make assessments as to the appropriate joist (or joists) to attach to with a response that meets all the H&S requirements for a proportionate response to possible risks. Everything is safer, the worm can stays firmly shut, risk has been significantly reduced and the OP also has something to reference and use as leverage for instigating a more manageable long-term program of equipment renewal.

 

You're obviously operating in a somewhat different world to me. From where I'm standing you're greatly exaggerating both the difficulty of upgrading the primary and the ease of adding a meaningful secondary. (As opposed to the other kind of secondary, the purely cosmetic variety.)

 

Regarding the last point, I think it is likely to have the opposite effect entirely: "But you just fixed it, why on earth do you want to fix it again?"

 

I'm uncertain as to the best course for the OP, but feel there are really only the two options there: fix it properly, or leave it alone.

 

I can see how my hurried response is not clear.

 

No, not at all. It was perfectly clear. :)

 

I was being deliberately obtuse. (Sorry.)

 

Of course I didn't think you were suggesting STAC could be wrapped around a bar. I was just being keen, now that the myth that STAC is "illegal" has finally been laid to rest, to also keep a lid on the myth that it ever was!

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Just picking up on something in the original post, about them being reconfigured for each show might come into effect.

Out of interest, what are the bars, and what are the kind of weights?

 

Maybe as some practical options, swapping steel bar for ali (depending on span and loading) could reduce some self weight, improve the attachment to the bar, improve the attachment to the ceiling, look at some rated hanging options. Try and work out what an actual approximate loading is and see how it compares to your gut feeling about the strength of the fixings.

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Whilst I've been around a bit, I just helped out at a new venue to me, a community theatre where I helped hanging lights.

 

I

 

* see if there were a bracket that would surround the rafter on all three sides and would take a bolt through it (and the rafter)

* replace the chain with rated steel rope

* find something to couple the bar to the rope

* suspend each bar from at least three (evenly spaced) places

 

My other challenge will be (as a new member) to get them to spend the money for something that is working fine for them.

 

Or...are my concerns unfounded? (I live by the motto "for a bad thing to happen just requires good men to do nothing")

 

would take a bolt through it (and the rafter) .

As others have pointed out making changes comes with responsibility . If you were to bolt thru for example you then reduce the structural integrity of the timber at the point at which you have attached a load

The same apples to structural steel as a industrial spark I do not drill fixings to attach equipment it may only be 2 x 6mm holes on a steel post but it still creates a stress line .

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