This article provides an overview of the
information contained in the new Analysis of Changes, 2005
NEC regarding a few of the more significant changes to the
requirements for fire pump installations in Article 695. The
revisions to the 2002 NEC rules include changes to the
overcurrent protection requirements, overcurrent device
selection, disconnecting means locations, power circuit wiring
sizes, and overload protection.
695.4(B)(1)
Overcurrent Device Selection | Figure
1 |
Change at a Glance. A new sentence,
"The requirement to carry the locked-rotor currents
indefinitely shall not apply to conductors or devices other
than overcurrent devices in the fire pump motor
circuits," has been added to the end of 695.4(B)(1).
Analysis and Effect
Overcurrent protective devices for fire pumps are required
to be capable of carrying the sum of the locked-rotor current
of the fire pump motor(s), the pressure maintenance pump
motor(s) and the full-load current of the associated fire pump
accessory equipment for an indefinite period of time. This
rule does not apply to conductor sizing. Conductor sizing is
determined by rules in 695.6, but it appears that there have
been instances where conductors and other equipment associated
with fire pumps have been required to be capable of carrying
motor locked-rotor currents indefinitely. The addition of this
new sentence to 695.4(B)(1) should clarify that the rule
applies only to the overcurrent device and helps eliminate
misinterpretation of the requirement.
695.4(B)(2)
Disconnecting Means | Figure
2 |
Change at a Glance. A new item (4) has
been added to 695.4(B)(2) regarding fire pump disconnecting
means.
Analysis and Effect
Disconnecting means for fire pumps are required to be
located remote from other types of disconnecting means in
order to reduce the likelihood that it will be inadvertently
opened by people who don’t recognize its purpose. A
principle focus of 695.4 is that of maintaining a continuity
of power for fire pumps because of the importance of that
equipment being operational when needed. There apparently has
been some misunderstanding as to what the term remote means and different locations have been selected for fire pump
disconnects. The new 695.4(B)(2)(4) has been added to help
clarify that disconnecting means for fire pumps are not to be
located in or near an enclosure containing other disconnecting
means.
695.5(B)
Overcurrent Protection | Figure
3 |
Change at a Glance. A new sentence,
"The requirement to carry the locked-rotor currents
indefinitely shall not apply to conductors or devices other
than overcurrent devices in the fire pump motor
circuits," has been added to the end of 695.5(B).
Analysis and Effect
Primary overcurrent protective devices for transformers
supplying fire pumps are required to be capable of carrying
the sum of the locked-rotor current of the fire pump motor(s),
the pressure maintenance pump motor(s) and the full-load
current of the associated fire pump accessory equipment for an
indefinite period of time. This rule does not apply to
conductor sizing. It appears that some have applied the
"locked-rotor current" rule to conductors and other
equipment associated with fire pumps by requiring them to be
capable of carrying motor locked-rotor currents indefinitely.
The addition of this new sentence to 695.5(B) should clarify
that the rule applies only to the overcurrent device and help
eliminate misinterpretation of the requirement.
695.6(C)(2) Power
Wiring | Figure
4 |
Change at a Glance. The text of
695.6(C)(2) has been revised regarding the sizing of
conductors supplying fire pump motors only.
Analysis and Effect
Wording in 695.6(C)(2) of the 2002 Code does not
provide guidance regarding the selection of conductors for
reduced voltage start motors. This change includes a reference
to 430.22 to provide a source of information regarding the
selection of conductors supplying across-the-line and reduced
voltage start motors. This reference also emphasizes that
sizing is based on motor full-load current and not overcurrent
protective device settings. Voltage drop is another factor
that must be taken into consideration in the selection of
conductors to supply fire pump motors as stipulated in 695.7.
This revised wording should be helpful in selecting the
correct size of conductors supplying a fire pump motor and the
reference to 695.7 alerts Code users that voltage drop
affects the selection also.
695.6(D) Overload
Protection | Figure
5 |
Change at a Glance. The text in 695.6
has been revised and the wording "Except as provided in
695.5(C)(2)" has been deleted from the second sentence.
Analysis and Effect
The wording in the main paragraph and Exception No. 2 of
695.6(D) has been revised to make the rules clearer. The
second sentence was also amended to delete the wording
"Except as provided in 695.5(C)(2)." With the
deletion of that wording, the second sentence now reads,
"Branch-circuit and feeder conductors shall be protected
against short circuit only." The deletion of this wording
makes the rule clearer and removes a source of confusion. That
wording could have been interpreted as implying that
695.5(C)(2) permitted or required a different application than
having short-circuit protection only. Branch circuits and
feeders supplying fire pumps are not permitted to have
overload protection in series with them.
695.6(H) GFPE | Figure
6 |
Change at a Glance. A new 695.6(H)
entitled "Ground-Fault Protection of Equipment" has
been added.
Analysis and Effect
Two existing rules in the Code prohibit
ground-fault protection equipment from being used with fire
pumps. Requirements for ground-fault protection of equipment
applied to feeders by 215.10 exempts fire pumps from having to
comply with the rule. The application of that type of
protection for services as covered in 230.95 also states that
ground-fault protection of equipment is not applicable to fire
pumps. While it should be apparent that GFPE is not suitable
for use with fire pumps because of the necessity for the pumps
to continue to operate even under fault condition, it is good
that specific language be included in 695.6(H) to make that
point very clear.
This preview provides a glimpse of a few of
those changes relative to fire pumps published in the Analysis
of Changes 2005 NEC. This information has been extracted
from the IAEI book Analysis of Changes, 2005 NEC where
information about other changes to the National Electrical
Code can be found as well. |
