light-man Posted January 9, 2013 Posted January 9, 2013 Hi All, I've recently inherited a system at a new job in which the 5-way IWBs and the Cyc bar are hung using chains in a studio style space with a fixed grid above. There are two hanging clamps per bar, with each chain then passed over the grid and shackled back to the hanging clamp. I have actually known this particular rig for many years, and as far as I can tell its always been the same, likely since its installation. However, I'm quite unsettled with it (I have been for some time, just not really been in a position to do anything about it despite making my feelings towards it known!), and it's something I've never encountered anywhere else. There's no SWL given either which is what really bothers me. I believe it's an 80s installation with very little updates, if any, so I don't know if its one of those older standards. To make it more secure, my immediate reaction would be to hang the IWBs in a permanent installation style using the correct clamps. My other option, in my own opinion, would be to use several double-ended G clamps and the current chains as safeties on each IWB and hang them as per regular portable IWBs. The most they'd be taking would be 4 or 5 Strand Preludes at most, though obviously there's nothing to stop anyone else just hanging anything on there without an SWL tag. I'm just wondering, what are other people's thoughts on this setup?
paulears Posted January 9, 2013 Posted January 9, 2013 I smiled a bit - my venue has 50 year old chains supporting some of the overhead equipment, and each year the engineers who come in testing and repairing have no concerns with them - as they're oversize for the load. If you are just worried, why not just buy some rated drifts, and use them as safeties, just in case a weld breaks or whatever you're worried about. If the drop is similar to double enders, use those instead of the wire rope style drifts. The absence of any labelling probably stems from the old feeling that these were not really a lifting mechanism, just a simple way of providing 'suitable' support. Same as when you see bars on studding. I see very few studs with labels? All this said, somebody should really be looking at your entire setup and certificating it annually, or whatever they decide is best for your use - if it's not been done, then when they do come in the first time, they'll assess what you have, test if necessary and produce a rating for each bar or system. Very often, old installations were far more substantial than they needed to be. Our first proper inspection found a lot of problems, but oddly, some bits were perfectly fine. A couple of FOH bars generated the question of what load. What load rating do you want - we were asked. I said, hopefully, er, 250KG?? He nodded and added to his notes. Afterwards I queried it - he said he had already decided the maximum he'd have been happy with was 500KG, so my request for half that was not worth fiddling with. We had two motorised LX bars installed with second hand motors from a big London venue that they'd removed and uprated. Same thing happened. I asked for 300KG on each one to discover the rating on the London installation was huge! They'd removed a number of extra sheaves from the winch drum as we needed 3, and originally there were 6 giving a rating of over a tonne! If you are worried, call in the experts, because they should already be looking at your kit and certifying it for the filing cabinet.
light-man Posted January 9, 2013 Author Posted January 9, 2013 Cheers for that Paul. The system is fully electrically tested annually by a local lighting company, though I'm not sure about anything else which leaves me with some concerns. I do want to get a company in to do the appropriate checks with regards to the grid, just for piece of mind unless someone randomly finds documents in the said filing cabinet! In all fairness, it would be better to be able to update the whole rig (its still running on 5A too), though with finances the way they are, I fear that's a bit too much to ask for!
paulears Posted January 9, 2013 Posted January 9, 2013 Nowadays, it's pretty vital to have your suspension system validated as 'safe' by people who know. The problem that you've identified is that you don't know how much load your system can cope with. While you're in control, and nothing changes, then the original safety of the system is probably still valid - BUT - if you're not a proper engineer, how can you be sure? Somebody might want to hang something else - maybe light or maybe heavy and you might be the person who says yea or nay. Can you actually do it? I was at a nightclub a while back putting in a new lighting control and spotted a couple of buttons labelled up and down. The manager prodded one to show me and a circular lighting rig crunched it's way down for lamp changing, but kept snagging up and suddenly dropping. I asked when it was last checked - they couldn't remember. I recommended the people who look after my venue and the condemned it! Wire ropes all frayed, rusty components - loads of weight just hanging above people heads by luck. It's a bit scary - but they just never gave it a thought. Nowadays, some insurance companies insist that all risk is itemised, controlled and signed off. A certificate in the filing cabinet that tells you the rig is safe and you can add up the weight load you have on it and sleep tight is a damn good thing!
light-man Posted January 11, 2013 Author Posted January 11, 2013 Yeah. I'll request the documents from the site manager, and if there aren't any I'll be getting someone in to check the whole system. I definitely want it to be checked by an engineer, simply so I can say yea or ney with piece of mind!
Wingwalker Posted January 28, 2013 Posted January 28, 2013 Give Stage Electrics in Bristol a call and ask for their Venue Services department. They should be able to sort you out right enough.
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