Terry: What happens to the derating
required if you bundle 50 lines, and tie them with plastic ties every
few feet into a solid mass?
What power can a cable, which is in
the center of the bundle, safely dissipate? This should be
one of the items which the TIA has
gone off for further refinement. The
reason that I bring this up, is that electrical inspectors are a bit jumpy
about this, and they
have no guidelines that either a contractor
or an NFPA official can point to, telling them that it's OK to bundle
in free air, or as mentioned
below: in either metallic, or
nonmetalic conduit.
Best Regards
Maurice Reintjes
MindspeedTM
Hillsboro, Oregon,USA
Office Phone (503)-914-5370
Mobile (503)-701-0797
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Subject
[8023-POEP] Cable ad hoc conf call min
Conference call minutes:
About 30 people in attendance, well attended by the cabling people.
Valerie reviewed the liaison from TIA and Shadi took questions regarding
the responses. It was noted that TIA plans to have input to IEEE by our
interim meeting in Jan.
The point was made that any temperature above the 20 degree operating temperature
should reduce the length of the cable in order to meet the TIA or ISO insertion
loss requirements. But the cable is rated to operate up to a maximum 60
degrees. There was a joint agreement that our objective should be to operate
the cable within the maximum temperature. The intent of the liaison is
to say a 10 degree rise due to the current in the cabling should not be
a problem provided that the cabling stays within its maximum temperature
rating. Note, there may be further refinement of this by the cabling group
after internal discussions.
There was a question about the 50% of the pairs in the cable are powered
or all pairs. In general people indicated that what was important is the
maximum current on any pair of the cable due to the current.
There was a question on the importance of knowing DCRU and it was indicated
this was important for 4 pair powering.
There was also a question about worst case testing conditions such as if
the cabling is in a conduit.
I think this was a good conference call and we have a general agreement
on the issues. At this point I do not plan to have another conference call
unless others think it is necessary.