A/C Color Code Is for Your Own Good
S. “Buc” Fitch, P.E., was reminded of the issue of electrical wiring color code
a few days ago. He opened a panel and found the entire “hot/phase” side wired
in black wire. This doesn’t help the tasks of load balancing and maintenance.
Fig. 1: Take note of the
wiring colors inside your electric panels.
the National Electrical Code doesn’t require a specific color code for ungrounded
conductors, electricians often use the following color system for power and
lighting conductor identification:
• 120/240V, single-phase wiring — black, red and
• 120/208V, three-phase wiring — black, red, blue and white
• 120/240V, three-phase wiring — black, orange, blue and white
• 277/480V, three-phase wiring — brown, orange, yellow and gray; or, brown,
purple, yellow and gray
the grounded side for neutrals, the wires have to be white or gray. Buc prefers
white at 120/240 (208) and gray for 277/480 circuits. Green or bare wire is always
the grounding conductor.
Buc specifies the latter 277/480 color grouping; that removes the “orange” wire
color and any confusion. Why? Orange is the only specified ungrounded conductor and marks the “wild leg” of a
120/240 center-tapped neutral delta configuration. For those unfamiliar: In
wild leg configuration, the two end phases on the center-tapped winding provide
120 volts to neutral, but on the wild leg you will find nearly 208 volts to the
If you see
an orange wire in a panel, alarm bells of caution should go off in your head. You
don’t want to wire a 120 VAC outlet across the wild 208 volt phase.
* * *
Previously we solicited feedback on the use of those laser-sighted infrared
Doherty of Skywaves has a Fluke 62. It has a 10:1 ratio and claims accuracy to
within 1 percent. Dave can testify that it works great in high RF AM
environments like that of 50 kW WCRN.
Dave has not tried it in a high-RF FM or TV environment. The instrument
works fine at Rhode Island’s WBRU(FM) and WHJY(FM), though the FM RF level in
the building is low there.
What have you experienced? Write to me at email@example.com.
These are useful devices for spotting overheated components. Dave
writes he’s also used long tie-wraps to keep J-plugs in place inside AM ATUs
and phasors. That won’t keep them from burning if the connections are loose,
but he uses the Fluke to keep an eye on that.
Fig. 2: White LED magnifiers
make troubleshooting easier.
The meter also is useful for checking the heat on those Lapp insulators
— before messing with the drain holes. (Dave loved the idea about
putting foam peanuts inside the insulators. It’s just too bad you have to shore
up the tower and disassemble the insulator to do it!)
* * *
speaking of those foam peanuts, Cumulus Boise Engineer Bill Frahm liked the
idea of putting a few foam packing peanuts inside a new base insulator to give
any water a place to expand, should the drain holes become clogged and the
But … Bill cautions to choose your peanuts wisely. Don’t use the ones
that are “eco-friendly” — sorry, but they will disintegrate when wet.
Fig. 3: Another brand of
* * *
Kuala Lumpur comes a neat idea from engineer Paul Sagi. He found the white LED-lighted
magnifier keychain assemblies, pictured in Figs. 2 and 3, which cost him less
than $4 each. Use your search engine to track these down; you’ll have lots of
* * *
Media’s Andy Soule commented on our discussion about the use of plastic pill
bottles. Andy writes that he quit smoking last year using nicotine lozenges. The
lozenges come in packs of four blue bottles; each one has a small silica
capsule in it to absorb moisture.
found the silica capsules handy and used dozens for this purpose. He tosses
extra desiccants into toolboxes, drawers, anywhere they can help.
The little blue bottles weren’t thrown away, either
— Andy had so many of them that he used them with some duct tape to make a
ladder line for a makeshift ham radio antenna.
Contribute to Workbench. You’ll help your fellow
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John Bisset has spent 43 years
in the broadcasting industry and is still learning. He is SBE certified and is
a past recipient of the SBE’s Educator of the Year Award. He works for Elenos