safety bond Installing new house lights - how to secure?

[james3mc]

I'm about to install new house lights in a small venue (Inspire Minis, each weighing 3kgs). The venue is a converted hall with timber roof joists. 

My current plan is to g-clamp each fixture over a short length of scaff which spans two joists. The holes already exist as there are little GU10s in the ceiling currently. I then want to add a safety bond which goes up and around a roof beam. But to do that I'd need safety bonds 2m long. 

Is that wise? I want a secondary suspension of some sort. 

[Dave m]

can't you safety bond to the bar?

Normally a lantern is only fixed to the bar immediately where it is.

If worried about the bar and lights falling, safety bond the bar with it's own wire.

 

looking at the images on line are they supposed to be hung off a mains cable? maybe it's just a way of showing the cable and if so, why do they have a hoop/saddle?

[Bryson]

If you're using them as a pendant, I would use the same approach as a pendant speaker and make a custom length piece of SWR as a safety with raw SWR and a swaging tool.

 

PS:  Chroma-Qs are made in Canada. 😉

[sunray]

I'm well out of touch. Are these sorts of rope clamp still allowed?..

.

  If so I'd have thought for 3KG they'd be more than enough.

[dje]

Out of interest - what risk do you anticipate in your RA, where you've deemed secondaries to be the best way of mitigating the risk? Can it not be mitigated using a different choice of primary suspension?

Personally I would say you can rig the fixture to the bar with a half coupler (generally considered a more permanent fixing) with nylock nuts; and forego the safety bond altogether. I think you can forego the safety bond on the grounds of risk assessment - the half coupler cannot be dislodged from the bar.

Safety bonds are a theatrical thing which make sense on G-Clamp'd fixtures located near where bars will move, tallescopes will be moved around etc - where there is a risk of dislodging the fixture. But in a permanent install where there are no moving bars etc, using a more secure primary fixing with locking fasteners is as secure as any of the non-theatrical installations (HVAC, Cameras, etc) which will tend to not have safety bonds either.

 

[sunray]

36 minutes ago, Bryson said:

If you're using them as a pendant, I would use the same approach as a pendant speaker and make a custom length piece of SWR as a safety with raw SWR and a swaging tool.

There I go, everyday's a school day...

I always believed swaging only related to 'increasing the size of a tube' (As an example: copper pipe joints are sometimes made by stretching one pipe so the other fits inside before brazing... kit for doing so https://www.vevor.co.uk/hydraulic-hose-crimpers-c_10823/7-lever-hydraulic-tube-tubing-expander-3-8-to-1-1-8-swaging-punches-hvac-tools-p_010173940130?gclid=Cj0KCQiAjJOQBhCkARIsAEKMtO2iwqdl2hw3N7rR2gn2KuFACGt7TjSFzAkdtg1UJK_Nx6t9NZQEVaMaAmncEALw_wcB)

[Bryson]

It might be a term more common in North America, to be fair.

 

To the point above about not needing a safety - that's a fair point if they're clamped, not suspended on the cable, there's nothing moving near them and (crucially) you are somewhere where there aren't many earthquakes.  Having said that, I remember the pictures of the ceiling collapses at the Apollo/Piccadilly, and the fixtures hanging on the safeties there after the incidents.  I'll bet the ceiling collapsing wasn't on the radar of the Risk Assessor, but I bet they're glad the safeties were there.

[sunray]

5 minutes ago, dje said:

Out of interest - what risk do you anticipate in your RA, where you've deemed secondaries to be the best way of mitigating the risk? Can it not be mitigated using a different choice of primary suspension?

Personally I would say you can rig the fixture to the bar with a half coupler (generally considered a more permanent fixing) with nylock nuts; and forego the safety bond altogether. I think you can forego the safety bond on the grounds of risk assessment - the half coupler cannot be dislodged from the bar.

Safety bonds are a theatrical thing which make sense on G-Clamp'd fixtures located near where bars will move, tallescopes will be moved around etc - where there is a risk of dislodging the fixture. But in a permanent install where there are no moving bars etc, using a more secure primary fixing with locking fasteners is as secure as any of the non-theatrical installations (HVAC, Cameras, etc) which will tend to not have safety bonds either.

 

I think it's a case of old habits die hard in theatres.

Personally I've gone through life with; 'why use 2 screws when 4 will do the job'.

 

[dje]

1 hour ago, Bryson said:

I remember the pictures of the ceiling collapses at the Apollo/Piccadilly, and the fixtures hanging on the safeties there after the incidents.  I'll bet the ceiling collapsing wasn't on the radar of the Risk Assessor, but I bet they're glad the safeties were there.

It's a fair point but it's just also not really relevant is it? It is just obvious physics that if the primary suspension is strong enough then the secondary is unnecessary.

The grid doesn't have a safety round it... what happens if that falls down?

I'm with sunray that it's habitual more than logical. I honestly challenge anyone to show to me the mode of failure which causes a 500kg-rated half coupler, secured with M12 locking nuts, to totally break in half but where the 3mm wire rope saves the day. I don't want to turn this into a bitching match about the necessity of safety bonds full stop... but for house lights which are mounted clear of any hazards which could dislodge them... it's just not necessary. Frankly when struck by the amount of force it takes to break a half coupler, most small fixtures will be the point of failure rather than the rigging anyway.

[dje]

1 hour ago, sunray said:

Personally I've gone through life with; 'why use 2 screws when 4 will do the job'.

 

So why not use two safeties?

[Bryson]

43 minutes ago, dje said:

It's a fair point but it's just also not really relevant is it? It is just obvious physics that if the primary suspension is strong enough then the secondary is unnecessary.

The grid doesn't have a safety round it... what happens if that falls down?

I'm with sunray that it's habitual more than logical. I honestly challenge anyone to show to me the mode of failure which causes a 500kg-rated half coupler, secured with M12 locking nuts, to totally break in half but where the 3mm wire rope saves the day. I don't want to turn this into a bitching match about the necessity of safety bonds full stop... but for house lights which are mounted clear of any hazards which could dislodge them... it's just not necessary. Frankly when struck by the amount of force it takes to break a half coupler, most small fixtures will be the point of failure rather than the rigging anyway.

 I'm agreeing with you in the most part - I was unclear at the start of the conversation if the OP is planning on hanging the fixture in "Pendant" mode or directly from the yoke.

In pendant mode, I would still want a safety.  But mounted as you say, I agree not really necessary, especially if adding one is onerous.  (The one caveat is if you have a keen but inflexible inspector who insists on one..)

[sunray]

48 minutes ago, dje said:

It's a fair point but it's just also not really relevant is it? It is just obvious physics that if the primary suspension is strong enough then the secondary is unnecessary.

The grid doesn't have a safety round it... what happens if that falls down?

I'm with sunray that it's habitual more than logical. I honestly challenge anyone to show to me the mode of failure which causes a 500kg-rated half coupler, secured with M12 locking nuts, to totally break in half but where the 3mm wire rope saves the day. I don't want to turn this into a bitching match about the necessity of safety bonds full stop... but for house lights which are mounted clear of any hazards which could dislodge them... it's just not necessary. Frankly when struck by the amount of force it takes to break a half coupler, most small fixtures will be the point of failure rather than the rigging anyway.

I'm afraid despite totally agreeing with everything  you say I habitually add a safety to these 50W RGB floods when I place them in the ceiling grid.

To clarify I remove a tile and lay in a 'T' of grid bars and rest 2 pieces of tile and the flood in, the extra grid bars clip together in the normal way but don't clip into the existing grid as there are no holes in the right place. I add a loop of wire through both extra bars, then use a single safety to the loop and the flood... despite the adjacent 4ft fluo fittings simply rest in the grid.

Edited February 10, 2022 by sunray
clarify

[dje]

24 minutes ago, Bryson said:

 I'm agreeing with you in the most part - I was unclear at the start of the conversation if the OP is planning on hanging the fixture in "Pendant" mode or directly from the yoke.

In pendant mode, I would still want a safety.  But mounted as you say, I agree not really necessary, especially if adding one is onerous.  (The one caveat is if you have a keen but inflexible inspector who insists on one..)

In pendant mode, yes agreed - as per my first post, it is about risk assessment, the safety bond has to mitigate a risk that the primary suspension cannot mitigate alone. 

 

So in the case of pendant fitting, the primary fitting may not be terribly strong, so the risk is that the fixture is subjected to unusual forces - ie caught on a tallescope being pushed past - mitigate it with a safety so even if the power cable breaks, the fixture does not crash to the floor posing risk of injury. 

 

In the case of a fixture secured to the mounting bar with a substantial mounting accessory (ie a half coupler), I cannot think of any risk where a safety bond would be able to mitigate it... Simply because the primary would cover all those bases itself. Any incident capable of breaking the primary would break the secondary, and/or the fixture itself. 

 

The inspector argument is always a valid one too and its really frustrating. The grid lights are seldom safetied, the air con is seldom safetied, the fire system is seldom safetied... I could go on. So yeah if you were hanging a Source 4 on a half coupler id say safety it just because it's theatrical lighting and best practice is to use a safety bond, and it'll keep the H&S man off your case. But for permanent lights up in the ceiling I really think you'll be fine with a high quality permanent installation fixing. 

 

 

[sunray]

13 hours ago, james3mc said:

I'm about to install new house lights in a small venue (Inspire Minis, each weighing 3kgs). The venue is a converted hall with timber roof joists. 

My current plan is to g-clamp each fixture over a short length of scaff which spans two joists. The holes already exist as there are little GU10s in the ceiling currently. I then want to add a safety bond which goes up and around a roof beam. But to do that I'd need safety bonds 2m long. 

Is that wise? I want a secondary suspension of some sort. 

I know scaf tube is THE theatre standard so I'm assuming the plan is something like the left: Scaff tube atop the joists with some sort of fixing each end, G clamp and length of studding.

As this is presumably being designed as permanent would using a piece of 2x1 or 3x1 timber be an easy/cheaper alternative: longer piece of studding and a couple of wood screws as opposed to G clamp and pipe fixings?

This is on the basis that I don't know whats there and how you're planning to position the lights.

Edited February 10, 2022 by sunray

[Stuart91]

Another option might be unistrut.