Walking on Wireways?

[jktwn]

I need to determine the load rating for Square-Duct metal wireway (8&quot. The electricians walk on the overhead wireways on occassion and the question of whether or not the wireways provide adequate support has come up. I don't see a specification for this in the technical documentaion.
From my research so far, neither NEC article 376 nor maufacturers of wireway list a specification for point loading from personnel walking on the wireways.
Can you help me with this question? Thanks.

 

[busbar]

The question seems more one of administrative policy and not an engineering matter. I do not think any wireway or tray manufacturer would furnish data; much less acknowledge in print any sort of “loading” allowance for foot traffic.

 

[RalphChristie]

I agree with busbar.

You can use the manufacturer's data (save load capasity for cables) and compare it with your cable load to see if the trays will carry both cables and personnel, but I still do not think electricians must be allowd on the trays, except in the case if they are pulling in cables or are doing some cablework on the tray. Also, if they are on the trays, they have to wear safety equipment like a safety belt.

RCC

 

[don01]

hi all
for cable tray and "cable way load capacity go direct to the manufacturer. They publish the load bearing capacity of the tray so you can calculate the max. cable load.

Now if you,ve done that then you aint allowed for say 60 to 80 kg of person. Although if they do walk on trays and cable way the concrete between their ears may make them even heavier.

Do the cable ways have hand rails? are they wearing harnesses ? etc etc.

On ALL sites I,ve worked at doing that would get you invited to go home and don't come back. And the union will not back the person.

All the best
Don

 

[wbd]

here in the USA, I would expect that OSHA would have alot to say (and $ fines) in the event of an injury from this "practice".

 

[jktwn]

The answer may not be so clear cut. In our company, we continuously assess risks associated with jobs when planning work. It may seem like a ludicrous question to ask about load capacities of wireways for walking but, then again, if you provide fall protection netting and cable tie offs for a harness, which we have, the risk has been somewhat mitigated.

As an engineer, I can look at the wireway structure and see immediately that it is not meant for foot traffic. On the other hand, there are many tasks that are inherrently unsafe but we manage to find a way do them safely by taking certain actions to mitigate the risk.

In this case, I agree with the members of this forum that it is unsafe in any circumstances to walk on energized wireways and am recommending the practice be prohibited.

 

[BJC]

This is taken out of a current specification for the installation of cable tray. It's pretty common and is also in NEMA standard VE2


"Label shall read "WARNING! THIS IS NOT A WALKWAY" in letters sized to the height of the side of the tray. "


Busbar is correct this is an adminstrative problem. In the worst case to be handeled with a pink slip. It's better and cheaper all around sometimes to train a new person that pay to fix ( or burry ) an unsafe one

 

[jktwn]

NEMA std VE2-2001 refers to open cable tray systems. Enclosed wireways such as our Square D 8"x8" wireways incorporate a hinged metal cover so you would not actually be standing on the conductors but on the cover instead (still a bad idea).

It appears to me that this NEMA standard refers to cable trays and not wireways.

I like the idea of adding caution labels to the sides and tops of the wireways.

 

[Nehemiah]

I have never worked at a facility that allowed us to walk on the cableways. We sometimes did for short stretches to reach something that was out of reach from the ladder but it was very frowned upon on only done on the weekends. It could have resulted in a write up. Especially if it was done routinely.