Sisal Rope

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jrannis said:
I wired a transferswitch last year that requried the use of lacing cord to prevent the conductors from jumping around. Not really that uncommon of a thing to see inside of switchboards, Even today.
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...and five years ago you weren't required to wear flash suits.

Did electricity changed?

No.

Did we discover anything new about the effects of electricity?

No.

So what happened?

Lawyers got involved and Corporations to cut their losses and make some money on the side and decided that we can spend couple of $B of money - and drive small businesses out of business as a side benefit - because we can't tolerate people getting killed by electricity. Never mind that vast majority of people who actually WORK with electricity already knew how to protect themselves, now we have protective clothing that actually produces less dexterity on the part of the workers and greatly increase the incidence ratio. Never mind that people getting injured by electricity in magnitude order less than any other hazardous industry. The tail is wagging the dog again.
 
combustible

combustible

Then why is it required in the manufacturers installation literature? If something were to happen and the cables not wrapped as required would the manufacturer honor their warranty? Does this in any way affect the UL labeling of the equipment?
 
weressl said:
Oh, and wait until it gets wet...that will be some fireworks.
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There is more space between the rope and the live connectors than there is between the connectors themselves. The rope can be wet and not cause any problems what so ever.
 
weressl said:
...and five years ago you weren't required to wear flash suits.

Did electricity changed?

No.

Did we discover anything new about the effects of electricity?

No.

So what happened?
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Actually the "roping" requirement comes out of the short circuit fault testing for the product. In many cases the conductors won't stay in the connectors long enough to complete the high current fault tests. The rope is acting like the bus bracing that is installed in MCCs or switchgear to prevent excessive movement and damage to the bus under fault conditions.
 
don_resqcapt19 said:
So is the insulation on the conductors and that burns much hotter and produces more toxic products of combustion.
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The ignition temperature is much lower. All components of electrical equipment must be fire resistant and preferably self estinguishing so why add a component that adds fuel, have a lower combustion temperature and adds an additional point of failure to the installation.

What happens with the UL listing?

Does UL recognize the sisal as a UR?

Does the listing specifies the exact material and exact installation method of the conductor bracing ties? How can UL assure that this field installed component will perform exactly the same way as in the testing - if there is such?

If it is required for SC bracing why isn't there an engineered component in the assembly that provides the bracing? Switchgears do not have such requirements and the 10-500kCMil/phase or more conductors at 6'+ unsupported length and 100kASC sure provide ample oppurtunity for magnetic mayhem.
 
Looking at the picture that Marc posted, it appears that the gap between the phase lugs is much shorter than the distance from the phase lugs to the rope.

That said, a gap through the air is a different sort of beastie than the creepage distance along the insulation surface, through the rope, and back down the insulation on another phase.

My hunch is that at 480V the roping doesn't present a significant flash over hazard, even when wet, but I have absolutely no experiences with such installations.

-Jon
 
weressl said:
My question would be: is this part of the UL approved testing procedure or is it just the manufacturer recommendation.

Was this tested by UL or only by Schneider/Square D.
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It is part of the UL test. As mentioned above, the conductors need to be stabilized during a fault condition (usually above 65kA).
 
weressl said:
What happens with the UL listing?
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The roping is specified in the manufacturer's instructions and it is UL's position (one that I don't agree with and have taken issue with many times) that any instructions provided by the manufacturer are 110.3(B) instructions and must be followed. As I recall the provided instructions specify the type of rope to be used. In this case the instructions specified sisal.
 
weressl said:
There is no such reference at another manufacturer even when it instructs of applying the UL508A.
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"Roping" instructions, from the equipment manufacturer, are common with MCCs and switchgear.
 
weressl said:
Yes when combined with dust ar other impurities readily available.
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What's it matter if those conductors are underground in a flooded pipe, or in a CT can with damp rope wrapped around them? Makes not a bit of difference.
 
mdshunk said:
What's it matter if those conductors are underground in a flooded pipe, or in a CT can with damp rope wrapped around them? Makes not a bit of difference.
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Weren't there homes in NOLA, panels under water ~ STILL hot?
 
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