Rockwell Automation 1770 DH,DHII,DH485 CABLE - Manual (Page 32)

Planning a Data Highway or Data Highway Plus
Cable System
Chapter 2
2-16
Table 2.C
Follow these guidelines for routing cables
Route this category
of conductor cables:
According to these guidelines:
Category 1 These conductors can be routed with machine power conductors of up to 600V ac (feeding up to 100 hp
devices) if this does not violate local codes.
Category 2 General guidelines - these guidelines apply in all cases.
• If it must cross power feed lines, it should do so at right angles.
• Route at least 5 ft from highĆvoltage enclosures, or sources of rf/microwave radiation.
• If the conductor is in a metal wireway or conduit, each segment of that wireway or conduit must be bonded
to each adjacent segment so that is has electrical continuity along its entire length, and must be bonded to
the enclosure at the entry point.
For Unrestricted Applications - these guidelines apply unless you can meet the restrictedĆapplication
guidelines.
• Properly shield (where applicable) and route in a raceway separate from category 1 conductors. They can
be routed in the same ladder or trough with category 1 conductors if barriers are used as required by NEC
to provide the separation specified in the following items.
• If in a contiguous metallic wireway or conduit, route at least 0.08m (3 in) from category 1 conductors of less
than 20A; 0.15m (6 in) from ac power lines of 20A or more, but only up to 100 kVA; 0.3m (1 ft) from ac
power lines of greater than 100 kVA.
• If not in a contiguous metallic wireway or conduit, route at least 0.15m (6 in) from category 1 conductors of
less than 20A; 0.3m (1 ft) from ac power lines of 20A or more, but only up to 100 kVA; 0.6m (2 ft) from ac
power lines of greater than 100 kVA.
For Restricted Applications - remote I/O, DH, DH+, and DHĆ485 cables can be bundled together with
category 1 conductors in a molded composite cable if the application can meet these guidelines.
• All category 2 conductors must be bundled together inside a common grounded 95% braided shield (with
100% aluminum tape shield) to separate them from the category 1 conductors in the larger bundle.
• Category 1 conductors must carry no more than 15A maximum at 120V maximum to power supply loads,
I/O circuit nonĆinductive loads, or I/O circuit inductive loads that are not switched by hard contacts.
• The total cable length of the remote I/O, DH, DH+, or DHĆ485 link must be limited to 456 meters (1,500 ft)
maximum.
Category 3 Route conductors external to all raceways in the enclosure or in a raceway separate from any category 1
conductors with the same spacing listed for category 2 conductors, where possible.
Article 300Ć3 of the National Electrical Code requires that all conductors (ac and/or dc) in the same raceway must be insulated for the highest voltage applied to any one of the
conductors in the raceway.