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Cable Trays in Class 1 Div 2 area

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richanton

Electrical
Jul 15, 2002
128
I'm having a heated discussion on this. The question is if I am using cable tray, and Type TC cable, is there some special sealing required at the boundary between the Class 1 Div 2 area and the non-hazardous area. My take is "No" if it's ladder tray, and I don't know what happens if its solid tray. The only sealing is at the enclosure the cable terminates at. Any opinions or links to discussion areas.
 
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Take a look at NEC 501.15 and be prepared to mull over it for awhile. There are many factors at play depending on your specific situation.
 
Section 501.15 is the right general reference, but 501.15(E)(1) and (3) is what you want to look at specifically.

A couple of things to note:

1. Cable Tray is not a raceway per the NEC (it's a support system).

2. UL's standard on Type TC says it has a "gas/vaportight continuous sheath," but is silent on whether it can transmit gases through the core. Assume it can. This is largely irrelevant to the OP, since a boundary seal isn’t mentioned in Subsection 501.15(E)(3).

3. In fact the only mention of a boundary in Subsection 501.15(E)(4) which doesn’t apply to Type TC.
 
Thanks. You have basically agreed with my interpretation and provided the missing link I did not have that UL 1277 says Type TC cable is gas/vaportight.
 
The issue is about fire class and additionally, as you mentioned, between hazardous and non-hazardous area. The requirement is "penetration MUST be sealed according to the intergrity of the boundary no matter ladder or solid tray is used".Generallry cable trays are terminated 100-300mm from the penetration ends depending on the size or group of cables.
There are some method in sealing of penetration;
a)Using a water base hardening compound, ex APEX
b)Using an MCT
c)Using an inert-heat activated sealant, ex RISE System manufactured by Belle Corp.
 
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