Fibreglass ladders for electrical work

[Jamtastic3]

Just wrap the top of your ladder in electrical tape :P

[ianknight]

A venue where I was once Chief LX (and those who know me will know where...) had foisted upon them a wooden A Frame ladder for focussing with, on the grounds that the on site Electrical Supervisor considered it a risk dealing with electrics on a metal ladder. This was queried a while later with a friendly H&S electrical inspector after the ladder became a little 'worn' - the inspector nicely pointed out that they themselves used metal ladders because they were more sturdy and less prone to wobbling...

[kerry davies]

Precisely, Ian. The need for insulated ladders where there are "exposed energised parts" or bare live wires is fairly obvious. If you really need fibreglass ladders in a theatre then there are a few more important steps to be taken before stipulating it. Like closing the place down before a rewire.

 

This appears to be yet another case of incompetent risk assessment by someone with absolutely no idea of the job-in-hand. Unfortunately the present government has substituted paper qualifications for the term competence and built a register of those deemed suitable to give advice on H&S.

 

As the http://www.oshcr.org/ list of six consultants for theatre contains one who means "operating theatre", there are really only three in Scotland and two in England. This register is not restrictive but does mean that being competent becomes a little more important when it comes to deciding who carries out RA's.

[Biskit]

Many thanks for the responses. Believe me, working for a local authority, I'm well aware of the over-zealous tendancies of H&S advisors! Just to answer the earlier questions, the intention behind the requirement for fibreglass ladders was borne from the issue of handling lanterns which, by necessity, need the power to be on for focussing. I agree this seems very OTT, especially as I can assure you all there is no question about the safety of our installed electrics, and a thorough PAT testing regime is in place for the lanterns.

 

It is a 'standard' demand around here for the use of such access devices for anything electric, perhaps made on the basis that the cost difference (vs. alu ladders/steps) is not enormous, and generally worth it even for a tiny benefit in terms of risk reduction. Another point which was made to me (nonsense or not, it was made) is that static build up, or even a couple of volts difference in earth potential between lanterns at height and the floor of the room, may cause a tiny contact shock, insufficient to directly harm but enough to unbalance and thus increase the risk of a fall from the ladder. Insulated ladders would mitigate this risk.

 

I do accept that with longer extension ladders the inherent 'wobblyness' of fibreglass may actually itself pose a more serious hazard, and I will be raising this point with the relevant people. I must stress I'm looking for the most sensible solution, hence my post! I'm in the fortunate (?) position that as this has been raised as a H&S concern, we do have the option of going for the best possible solution, even if many (me included) feel it is way OTT!

[Brian]

How do they propose to handle the situation where one lantern might have a live shell whilst the one next to it presents a nice sturdy earthed body? What's to stop you touching one with your right hand and the other with your left thereby receiving the full mains voltage across your heart?

 

If they honestly believe that metal ladders are a risk then surely they must have considered this scenario?!

 

 

 

And I believe that an insulated ladder will increase the risk of static shock. As you climb your clothes will rub the fibreglass creating a static charge which you will discharge as you reach the bar.

[Biskit]

Fair comments Brian, again I will point them out. This is by no means an open/shut case. If I go back with a report of the various risks and benefits, common sense will prevail. I just need to ensure I have the correct info (including what is considered 'standard practice' - as a venue I'm aware we are rather isolated, despite our best efforts to keep in touch with the rest of the industry!).

 

On the live lantern next to earthed one and touching both - surely this particular risk exists no matter what access you use (even standing on the floor!)? Aside from simply not doing the job there's not a lot we can do about it apart from keeping electrical maintenance standards high. Doesn't mean we should just ignore all other risks.

 

Regarding the specific point about static build up increased by fibreglass ladders, is this known to happen? If it is, it would seem daft to recommend their use for any electrical work as you'll pretty much always have the opportunity to 'earth' yourself and discharge at the top of the ladder!

[Brian]

My tongue was firmly in my cheek when I wrote my last post.

 

A well maintained lantern is unlikely to ever have a live body. Even if a wire does come loose inside and contact the shell AND the earth lead is disconnected then the very fact that the whole lantern is bolted to an earthed bar means the circuit protection will kick in. Which rather begs the question why an insulated ladder.

 

As for static; I'm still looking for where in the Tribolectric Series fibreglass sits.

[kerry davies]

Don't really know how to approach your H&S guys but try asking about the hierarchy of risk which is the ERICPD thing I mentioned earlier. Just in case others don't know the acronym it stands for; Eliminate, Reduce, Isolate, Control, PPE and Discipline, in that descending order. They have gone for isolate before eliminate by my reckoning.

 

In your case there is no reason for the use of insulated ladders as there should be no bare wires carrying electricity which may be conducted to the ground/those footing the ladder. If there is that risk then other, earlier safety measures need to be undertaken as an urgent priority. Once those hazards (loose lumps of unprotected electric floating round the grid) have been dealt with the safest most stable means of access should be used and bouncy GRP ladders ain't it.

 

In their hypothesised case no housewife, anywhere would open a fridge without big rubber gloves and wellies.

(Now there's an erotic vision for you.) You are not dealing with the national grid after all.

[pritch]

In their hypothesised case no housewife, anywhere would open a fridge without big rubber gloves and wellies.

 

Kerry's (slightly flippant, but we'll let it stand!) example does bring up an interesting point... what exactly would they like you to do when you're focussing a lantern that can be reached without ladders? Stand on a ladder anyway just to provide a bit of extra protection?

 

Also, if it's the case for anything electric, what does a handyman using an electric drill have to do? Do they have to have fibreglass ladders too?

[ramdram]

Now the subject of H&S has arisen then surely the glass fibre ladder ploy is a standard CMA (cover my @rse) exercise by the senior staff top bods...who did not rise to those dizzy heights by ignoring said H&S thing. The Electricity Boards sometimes use red f/g kit and ditto BT with blue f/g ladders. Perhaps a natter with one of those blokes...who actually use the kit, might shed some light on the reasoning?

 

If there is a budget for H&S then why not have a posh fibreglass ladder? (t-I-c warning) However, bearing in mind the weight of these ladders there might be a problem of lugging the thing around and adding to operator fatigue.

 

Plus if anyone has had the misfortune to handle a glass fishing rod where the varnish has rubbed off will know all too well how itchy glass fibres are. raising the possibility of damage to the fibre glass "structure" of the ladder. There are regular checks on the access items so if a tiny piece of fibre glass gets chipped off, would that render the kit "unsafe"?

 

Fascinating subject this, who'd have given a moments notice to the tribolectric angle?

 

Or, what about carbon fibre ladders? Light as a feather it seems:

 

http://robinson-solutions.blogspot.com/2008/11/carbon-fiber-ladder.html

 

but, ahem, it might be considered a tad conductive...

[ceecrb1]

I can do you all a great deal on some "insulated zarges"..

 

Just like the real thing but give me an hour and a few rolls of lx tape.. job done!

I'll even let you pick the colour!

 

phone me for a quote http://www.blue-room.org.uk/public/style_emoticons/default/laugh.gifhttp://www.blue-room.org.uk/public/style_emoticons/default/cool.gif

 

Equally I can do insulated parcans, insulated truss, insulated lighting bars... you name it.

[Biskit]

Equally I can do insulated parcans, insulated truss, insulated lighting bars... you name it.

Would two layers of tape count as 'double insulated' :** laughs out loud **: ?

 

Yes I do realise this has all got a bit daft. We will be meeting with the H&S 'advisor' (yes that is actually his job title) shortly, when hopefully some common sense will prevail.

[Tomo]

The first question to ask is exactly what fault condition this is trying to protect against.

 

The casing of lanterns cannot go live without a double electrical fault, the first of which should be spotted by visual, PAT and/or fixed installation testing long before the second fault could occur.

 

If they think that double fault is likely, then RCDs on every ladder-accessible channel are a much more effective protection measure. You might already have those anyway.

 

Then you can knock it out of the water and get the right ladder for the job.

[ramdram]

But, if you see here:

 

www.hse.gov.uk/pubns/indg247.pdf

 

Page 14 mentions a caveat with some types of dimmer and RCDs. It continues along the lines that an RCD is not really suitable for protecting the secondary circuit of the dimmer, ie the lantern side.

 

There is some divided opinion too on what class of RCD to use on dimmers. I raised this question on BR almost a year ago to the day so you could search if interested.

 

Returning to the ladder issue, if your H&S advisor is the one who actually does the advising then your management would be silly not to heed his/her advice so if anything went awry they take a backward step and state they followed "best" advice.

[Tomo]

But, if you see here:

 

www.hse.gov.uk/pubns/indg247.pdf

That document is more or less what you could term "Lies to children", except of course that's completely the wrong concept.

(Caution - tvtropes.org, major timesink!)

 

It's intended for the level of your average pub landlord and Dodgy Dave Double Decks.

- The people who want 'some lighting and sound' but aren't going to spend much time reading up on how to do it safely.

 

Page 14 mentions a caveat with some types of dimmer and RCDs. It continues along the lines that an RCD is not really suitable for protecting the secondary circuit of the dimmer, ie the lantern side.

It's badly phrased and you've misunderstood.

 

Load-side RCDs for a dimmer are generally unreliable (as they'd have to work with an interrupted supply voltage), which is why RCD-per-channel dimmers aren't built like that.

- The RCD is on the supply side of the power control electronics, where the full supply voltage is always available to drive the RCD mechanism. (Eg ETC Sensor+/Unison/Matrix II, Strand EC21 etc)

 

If the dimmer pack doesn't have its own RCD(s) and you want to add some, you shouldn't feed too many dimmers from one RCD as all CE dimmers have a small amount of leakage to Earth. If you put too many on one RCD you could exceed trip leakage.

- This is also true of pretty much every bit of electronics you'll use. (EU regs do give different limits for leakage currents for each kind of equipment)

 

If it does have RCDs, you shouldn't feed it from an RCD-protected supply without carefully setting up time-based discrimination.

 

The "DC" comment is presumably because there is a type of RCD called "Class AC" that doesn't trip on a half rectified AC (pulsed DC) fault, as you could get if one side of an SCR/Triac dimmer failed.

 

Class A RCDs will trip on pulsed DC as long as it touches zero-cross at least once per mains cycle. (Normally it touches twice per cycle, eg half-rectified)

 

There is some divided opinion too on what class of RCD to use on dimmers. I raised this question on BR almost a year ago to the day so you could search if interested.

Class B RCDs are intended for odd mains power supplies and things that have 3-phase rectifiers, where there's a possibility for a continuous DC leakage that never touches zero.

They will trip on a smooth DC current that never touches zero-cross, while a Class A may not.

A normal mains voltage dimmer system (like SCR/Triac/IGBT/Sinewave) cannot do that.

 

In theatre, the only things you're likely to encounter where Class B may be needed are 3-phase motor drives in stage machinery. That's usually installed by a specialist who should know what to use for their particular kit.

 

For life protection in a normal dimmer system, you want Class A 30mA RCDs.

 

The question is really whether you go for RCD-per-pack or the better (and more expensive) RCD-per-channel.

 

This has got rather off-topic though...

Possibly wants merging with: http://www.blue-room.org.uk/index.php?showtopic=40964&st=0&p=341211entry341211