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The following describes the use of Power Strips and Extension Cords
with NTRAK Modules and in NTRAK Layouts. Recent changes in the National
Electric Code and International Fire Code restricting the use of Power
Strips and Extension cords is concerning us. While aimed more at Home Office
and Dorm rooms and their use more as permanent wiring than our weekend
layouts use them, we must be aware of the code being enforced by Fire
Marshals in public buildings. See the Background,
below, for more of the "why" of these requirements. Modules that have
NO NEED for 120 Volts AC should have the Power Strip removed from the
module. Note: The following has been reviewed and accepted by the Eugene,
OR Fire Marshal. Future changes will be made as needed. Jim F.
AC Power distribution on NTRAK Model Train Modules
The following NTRAK guidelines are based upon Chapter 6, Section 605 of
the International Fire Code and applicable sections of Underwriters
Laboratories Product Standards UL-817 (Cord Sets and Power Supply Cords) and
UL-1363 (Relocatable Power Taps), and are believed to comply with most local
codes. In the event of discrepancies, local codes will govern. If there are
any questions, consult your local fire marshal.
- Remove all power strips from modules. Also, remove all AC power cords
and outlets from modules.
- Use a grounded (3-wire) commercial quality power strip (14 AWG cord,
preferably 15 ft long) with 15A circuit breaker to plug into an approved
branch circuit wall outlet or power drop.
- Although not required, a GFCI adapter or GFCI pigtail inserted between
the outlet and the power strip is recommended. Alternately, a GFCI
equipped power strip may be used in 2) above.
- Grounded, UL approved (no home brew!) multi-outlet extension cords
(triple outlet at the end, or multiple outlets along the length of the
cord) should be used to distribute 120 VAC from the power strip to points
of need on the layout. Extension cords should be 14 AWG minimum for up to
50 ft, 12 AWG for 50 to 100 ft.
Extension cords should be placed, wherever possible, in non foot traffic
areas but not concealed or covered by equipment. Extension cords can be
temporarily attached along the bottom of modules above floor using twist
ties, zip ties, S-hooks, etc. No permanent attachment is permitted. Cords
should not be routed through clamps and or holes in module frames. This
should be done neatly.Damaged cords should be discarded and replaced.
Repairs should not be attempted. Cords that must be placed in areas
subject to foot traffic should be at minimum secured to floor along their
length with tape. In some jurisdictions, Extension cords subjected to
foot or equipment traffic must be further protected from damage:
* Cords 3/8" or less in diameter must be covered with hard plastic
"office cord covers" or an approved alternate method. * Cords larger
than 3/8" in diameter must use a plywood ramp style cover, or an
approved alternate method. * All cord covers must be secured in place
using tape, nails or other methods.
- Power supplies for throttles, boosters and accessories must be
off-module, either on the floor or a suitable cabinet or shelf under the
layout. (This includes "wall-warts").
- Throttle, booster and accessory power supply line cords and
wall-warts should be plugged directly into the extension cord outlets.
"Power cubes", multi-taps or other outlet expansion adapters shall not
be used.
Low voltage power distribution
With the loss of the ability to plug multiple wall-warts into a
module mounted power strip, the more accessorized modules need a way to
get power to their accessories. The following approach is therefore
suggested:
- The white line remains reserved for layout wide 12 VDC power
distribution, and will continue to be used to supply DC throttles.
Permissible white line usage, however, may be expanded to also include
on-module 12 VDC accessories on a secondary (not to interfere) basis.
Such accessories shall be easily disconnected from the white line if
necessary. A Powerpole or CJ white line "T" tap to feed accessories is
recommended for this purpose.
- (Updated 11/4/2006) An optional accessory bus may be implemented within a module set
or group for local accessory power (12 AWG,
Brown/Black, horizontal Powerpoles, Brown on the left), and may be powered with 14-16 VAC from
a separate power supply or transformer as desired. On module rectifier
circuits would be used if DC is needed. Note: This bus is NOT intended
for layout-wide power distribution!
(Note: The color change to brown from gray
(the previous color) is due to the wider availability of brown tape
for marking things over gray tape!)
- All low voltage supply outputs shall be ungrounded and include
over current protection (fuses or circuit breaker) where appropriate.
Background
on the need for this change
Early on, NTRAK recognized the need to distribute power for on-module
accessories and other miscellaneous requirements. Initially module-mounted
outlet boxes and cords were recommended as a way of providing an "AC bus"
for such purposes. In 1988, in recognition of possible safety issues
with such "homebrew" approaches, the recommendation was changed to use
commercial, UL-approved power strips with each module. While not mounted
to the modules, these would be plugged together to extend AC power down
the layout as needed. In July 2004, an amendment was issued to the
National Electric Code in UL 1393 concerning the use of such power strips
("Relocatable Power Taps" in NEC parlance), stating that "A cord-connected
Relocatable Power Tap is not intended to be connected to another cord-
connected Relocatable Power Tap". This technically put the typical NTRAK
AC power configuration at odds with the code, even though our power usage
was low and presented little danger of the overloads the NEC revision was
designed to address. With the temporary nature of most of our setups,
this has not previously been an issue, however in April of this year, the
Eugene, Oregon group was flagged by their local Fire Marshall for the use
of "daisy-chained" power strips, and although they were allowed to
continue the show, they were informed that future setups must be
code-compliant. Safety inspectors elsewhere around the country have become
more rigorous in their enforcement of this provision as well, and this
trend is likely to continue. As a result of the recent code change, and
possible increased enforcement of this provision, NTRAK can no longer
recommend the use of power strips in a daisy-chain configuration.
Accordingly, and after a review of other applicable codes and standards,
our recommendations on AC power distribution via power strips and
extension cords are revised as follows:
- Power strips must be UL approved 3-wire (i.e., with ground) rated
for 15 Amps (14/3 gauge wire or better) and shall include a 15 Amp
resettable circuit breaker. For flexibility purposes, a 15 ft cord is
recommended. Power strips meeting these guidelines include the
Weber/Tripp Lite 6SPDX-15, Hammond 1584H6B1 or similar.
- Extension cords must be UL approved 3-wire rated for 15 Amps with
outlets along their length or three female outlets at the end. For
extension cords of 50 ft length or less, this means 14/3 gauge wire.
Cords greater than 50 ft and up to 100 ft in length shall be 12/3 gauge.
- Power strips may ONLY be plugged in to an "approved receptacle"
(i.e., wall outlet or permanently wired power drop).
- Power strips may NOT be plugged into one-another ("daisy chained")
or into an extension cord.
- Extension cords may be plugged into power strips, but may not be
daisy-chained.
Ground fault Circuit Interrupter (GFCI) protection, though not
required, is nevertheless recommended, particularly in outdoor venues. As
the "first line of defense", GFCIs may be incorporated into a
wall-connected power strip, via a wall plug adapter (Grainger 5YL43 or
similar) or in-line adapter (Technology Research Corp. # 14880-4-001 or
similar).
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NTRAK Modular Railroading Society, Inc