Hazardous Location Brigde Crane

[ChipFuller]

We are installing a 3 ton explosion proof bridge crane here at our plant. The area is rated Class I Division 1 Group D and Class II Division 1 Group F & G. According to the NEC the cabling should be rated extra hard usage. This would be like SO cable. We would like to use a festoon system with flat ribbon cable because it has less problems when coiling and uncoiling. Is there a flat ribbon cable made rated for extra hard usage? What others are doing for bridge cranes in hazardous locations?

Thanks

 

[dpc]

Have you talked with the crane supplier? Seems like an "explosion-proof" bridge crane would have to take the power delivery system into account. Normally the festoon cable system is provided as part of the crane, at least in my experience.

It would be best to have the crane supplier's fingerprints on the explosion-proof rating all the way back to your fixed power disconnect switch.

 

[ChipFuller]

Yes, the crane vendor is looking into this. In previous installations, the vendor has installed flat ribbon cable with the same outer covering as SO cord, but the flat ribbon cable does not say it's rated extra hard usage. Like I questioned before, what's the rest of the industry using in hazardous locations for bridge cranes?

Thanks

 

[BJC]

In my experience the SO cable power feeds seem to work fine. The supports for the cable have to be aligned properly and maintained.
In additon to power cable I think your going to need an air line to pressurize the big enclosures and at least two wires to operate the breaker that feeds the crane.
Enclosures on the crane are pressurize slightly over atmospheric. If any on them are opened a pressure switch is used to shut down all power to the crane.

 

[ChipFuller]

Thanks for the information, but at our plant we've experienced problems using SO cords for festoon systems. The cord doesn't lay nice and flat like ribbon cable and then becomes tangled up.

For the hazardous location, we are installing the controls in the equipment room rather than up on the crane. Our previous experience with having the controls on the crane is that it becomes very laborious removing all of the bolts used for explosion proof enclosure.

We have used the Bebco style pressure switches on other equipment when can't purchase something rated for the hazardous environment.

Thanks again

 

[Thom2005]

I have a question reqarding your crane.
What requirement is there for your mechanical componet design under this hazardous classification. The festooning for example has sliding metal components. Is there a code that determine what designs/materials you select?

What about the wheels, is there a code that determines if the crane wheels are suitable for this environment