Audio Cable Passing through Hazardous Area

[Stanfi]

I have an audio cable for a intercome system that will pass from and non-hazardous area to another non-hazardous area, but in route will pass through a hazardous area. My question is if this cable needs pass through intrinsic barriers? If so, will it degrade the signal quality?

Thanks

 

[VisiGoth]

Distance and electrical interference vs shielding should be the issues and none are related to a hasardous area. If the hazerdous area requires a bulkhead break you may not be able to do source end shild grounding only and may have to have multiple grounds (making ground loops). The standard distance issues should be your limiting factor. If you have transformer isolation and shielded twisted pair and good connectors you should be OK.

 

[itsmoked]

I thought normal intercoms ran with high voltages 80-90V and some minor current. Would seem to be a barrier power limiting problem.

I don't recall but is a hazardous wire actually in the hazardous area if it remains in a sealed metal conduit,(the threaded stuff), that originates and ends in the non hazardous areas?

Somebody back me up!

 

[dpc]

Yes, most intercom systems use 70V or so for distribution with an impedance-matching transformer at each speaker.

I suspect this would be a problem if you have any devices in the classified area. If you run rigid steel conduit with appropriate construction methods and no splices, you can probably pass through a hazardous area, but my memory is a little hazy on that (and other matters).

Might check with the Gai-tronics folks to see if they have a solution.