Rigging Lighting from a hemp bar

[Trunker]

Hi all, just looking for some clarification on a situation I may have in a few weeks time. A venue I work at has 3 lighting bars on Winches rated at 100kg SWL per bar. There are also hemp sets rated at 150kg SWL per bar.

 

To light a back cloth I need extra channels and a 4th LX bar. Would it be bad practice (maybe unsafe?) to rig 4 Coda/4 battens (weight 11.6kg each) off this bar to light the back cloth due to it being hemp?

 

I can’t see weight being a contributing factor as the tab tracks on the other bars (along with legs etc) are a fair weight too! Any suggestion comments? Should the hemp bar with LX have additional slings? Or is it fine if tied off correctly?

 

Many thanks in advanced and sorry if in wrong topic.

[paulears]

I'd happily do it with this kind of weight

[Trunker]

Thanks Paul. That’s my thought. I’ve had somebody say that is not acceptable as it requires a 2 man lift on the hemp ropes. But most hemp ‘pulls’ require a 2 man lift in my experience.

[Bryson]

That seems mostly unremarkable for a hemp house with experienced operators. They might grumble a bit but it'll work. They may even throw a sandbag or two on for some old-school counterweight assist.

 

Now, if it's a community run or otherwise non-pro venue running hemp, that may be a different animal.

[indyld]

Wasn't that long ago that in a mixed house, whole bars full of LX went on the hemp sets due to the need for all the counterweight bars for show flying (along with cloths on hemp). Of course, many of these houses have since been converted to all counterweight and many to winch assist. Dunno about practice, but pretty sure physics hasn't changed all that much.

 

Full LX bars were often a 3-4 person lift, made easier by multiple floors. As you say, at least two on much more than an empty bar not least for additional security when fumbling with tie-off or snags etc.

 

As an aside, not only are tab track bars with full blacks on them often pretty heavy but remember that the shift in point load can put considerable imbalances on the pick ups during use.

Edited December 18, 2019 by indyld

[Trunker]

Thanks for all your replies and confirming everything. I’m obviously dealing with a jobs worth here.

 

As a side note, should all hemp bars and winch bars be tested And certified annually? Should there be a certificate for the bars? Or just visuals done every time they are used? The ‘technical manager’ (loosely termed) says there is not need for a certificate.

[David Ripley]

Thanks for all your replies and confirming everything. I’m obviously dealing with a jobs worth here.

 

As a side note, should all hemp bars and winch bars be tested And certified annually? Should there be a certificate for the bars? Or just visuals done every time they are used? The ‘technical manager’ (loosely termed) says there is not need for a certificate.

 

Yes - It's a legal requirement under LOLER - Lifting Operations and Lifting Equipment Regulations 1998

 

Specific info on Inspections:LOLER Inspections

 

David

[Trunker]

Thanks David. The same guy has told the management that it doesn’t need to be be done as it doesn’t come under LOLR, which I knew was wrong as it is lifting equipment.

 

I do quite a bit of work at this venue, so I’ll have to broach the subject sensibly to avoid negativity outcomes.

[gareth]

Hanging LX on hemp sets used to be fairly commonplace. Not so much so these days, but it still happens. (Haven't done much commercial touring for a few years, but going into the Theatre Royal Brighton - entirely hemp - used to be a wonderful experience just to see what weird and wonderful systems the redoubtable Roy Wroe would come up with for jerry-rigging some counterweight assistance for any particularly heavy bars...)

 

Anyway, four Coda4's is well within limits of what you can happily hang on a hemp set - as long as the lines are in good condition and not frayed to hell! Might be worth giving it a visual once-over before you hang anything on it.

[Marco Jardim]

Is it even legal to have static or dynamic suspended loads over people head’s with hemp rigging or any  type other than steel wire rope?

sorry for the English 

[J Pearce]

Absolutely fine. The rope used should be designed for the purpose, have a safe working load determined by a competent person, and should be regularly inspected by a competent person. Any knots or other terminations (splices etc.) should be made by a competent person.

There's nothing instrically safe about steel wire rope. It too can fail if overloaded, poorly made, mistreated, damaged etc.

[Marco Jardim]

Thank you for your clarification

Could one argue that steel wire rope is safer if in proper conditions, due to it’s higher resistance against external factors like a fire ( would prevent in some degree the falling of the rigged equipment) 

I know in Germany it’s forbidden to rig equipment for example on a fly bar with only textiles without a back up safety steel cable,  or any synthetic or natural fiber ropes

 

[J Pearce]

Ah, the old steel in a fire routine. Have a look at the softening temperature of a crimped aluminium ferrule - a very common termination for steel wire rope.

[Marco Jardim]

👌

on point, very compelling argument 

thank you very much sir

[sunray]

6 hours ago, J Pearce said:

Ah, the old steel in a fire routine. Have a look at the softening temperature of a crimped aluminium ferrule - a very common termination for steel wire rope.

One of the night clubs I did some work in had a 160A 3ph supply to a moving light rig, big structure with 2 moving leaves which could flip over, one side full of rolling boxes, hundreds of pin spots, Martin Roboscans etc, and the other side had 4x4 CRT video wall. The 3ph supply flex rubbed through on such a ferrule and arced as it moved until the crimp burnt and failed.

Edited January 28, 2022 by sunray