NFPA Journal - January/February 2020 - 44

In Compliance
Chapter 24 provides the first location where you can find a requirement
for cable survivability. Only systems
employing relocation, or partial
evacuation, require the survivable
performance of cable and associated
equipment. What you will not find is
the "why" for this specific requirement
in the code. But if you think about the
survivability requirement in Chapter
24, the unspoken performance requirement intends for the speakers on the
floors above the fire floor to continue
working during the suppression
efforts. The speaker circuits inevitably pass through the fire floor and, in
order for the fireground commander to
continue to provide valuable information to those occupants and the floors
above the fire, the circuits must have
protection.
Can we reduce or eliminate this
requirement? You can find the
answer in the code. A new paragraph
24.3.14.4.1.1 states, "Where notification zones are separated by less than
two-hour fire-rated construction, a
pathway survivability of Level 1, 2, or 3
shall be permitted."
Another new section provides relief
from the two-hour requirement by
using Class X or Class N wiring methods for all notification appliance
circuits "installed with the incoming
and outgoing pathways separated by at
least one-third the maximum diagonal
of the notification zone."
Finally, the code does not require
survivability, regardless of construction
and building height, if the emergency
plan does not employ relocation or
partial evacuation of the occupants. It
would appear that the 2019 edition of
NFPA 72 resolves the question considered by the NFPA 72 Chapter 24
technical committee.
However, the technical committee
has formed a task group to determine
the need for any additional changes.
The stated goal, after all, remains
ensuring the reliability of the fire
alarm system performance.
Wayne D. Moore is vice president at Jensen
Hughes. NFPA members and AHJs can use the
Technical Questions tab to post queries on NFPA 72
at nfpa.org/72.

44 | NFPA JOURNAL * J A N U A R Y / F E B R U A R Y 2 0 2 0

NFPA 70 + 70E

Electrical Safety

2020 NEC revision adds
safety provisions for
service equipment work
By Derek Vigstol
he 2020 NFPA 70®,

T

National Electrical Code®
(NEC), features a number
of revisions designed to
protect people from electrical hazards. One important change to
the new edition addresses safety for
people working on service equipment.
The "six disconnect rule" has been
around for a long time-we've been
permitted to use up to six switches or
circuit breakers in a common enclosure
as the service disconnect since before
World War II. However, this created
a scenario where the bus in an enclosure could not be de-energized without
disconnecting the service from the utility.
This presented a massive hazard to
workers when performing work on
services, since they were the point in the
system with the highest available fault
current and potential arc-flash incident
energy. This was also compounded by
the addition of alternative power sources
on the supply side of service disconnects, such as solar and wind power.
Essentially, this created a state where
workers were exposed to equipment that
could not be put in an electrically safe
work condition.
NFPA 70E®, Standard for Electrical
Safety in the Workplace®, requires that
equipment be placed into an electrically
safe work condition if a worker could be
exposed to a shock hazard, or if there is
an increased chance of injury from an
arc flash. There are some specific conditions that justify not placing equipment
in a safe work condition, such as when
it's not feasible to de-energize or when
de-energizing poses a greater hazard
or increased risk. However, needing
to disconnect from the utility or other
power source is not a justification for

energized work. That meant workers
were often needlessly exposing themselves to this dangerous situation.
The solution: provide a way to turn the
electricity off without involving the utility
or altering any supply-side connections
from other sources. That's the focus of
the new revision to section 230.71, which
says that each service must only have a
single means of disconnect.
Exceptions are almost always inevitable for these kinds of general rules, and
this one is no different. For instance,
occupancies like shopping centers,
multi-family dwellings, and office buildings benefit from having multiple
disconnecting means on a single service,
a commonly used design feature in these
instances. To address this, 230.71(B)
was also revised to list a set of conditions where the design can utilize up to
six disconnects. This is a very specific
list of conditions that must exist in
order to have multiple disconnects on a
single service. Two to six disconnects are
permitted, provided that they consist of
a combination of any of the following:
separate enclosures, each with a main
service disconnect; panelboards with a
main service disconnect; switchboard(s)
with only one service disconnect in each
separate vertical section with barriers
separating sections; and switchgear or
metering centers where each disconnect
is in a separate compartment.
This means that a "main lug only"
panelboard can no longer be fed from the
service conductors with individual circuit
breakers serving as the service disconnecting means-a major step forward in
requiring safety by design when it comes
to worker wellbeing.
Like other requirements in the NEC
that consider worker safety, this change
to the latest NEC will take some adjustment in system design and installation.
However, when we fully understand that
the driving force behind this change is
preventing injuries to workers servicing our electrical equipment, we can see
just how important this change is to the
purpose of the NEC.
Derek Vigstol is an NFPA technical lead, Electrical
Tech Services. NFPA members and AHJs can use the
Technical Questions tab to post queries on NFPA 70
at nfpa.org/70next.
http://www.nfpa.org/72 http://www.nfpa.org/70next
NFPA Journal - January/February 2020

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