SUPPLEMENTAL CORRECTION SHEET
FOR
SERIES RATED OVERCURRENT PROTECTION
This is intended to provide uniform application of the codes by the plan check staff and to help the
public apply the codes correctly.
PLAN DETAILS
G
1.
Provide manufacturer’s specification sheets, identifying the fuse class , the circuit breaker
manufacturer, model designation, type, number of poles and electrical rating used as part
of the series rating. (240-83(c), 110-9, 93.0404, UL Recognized Directory)
G
2.
All overcurrent devices in an emergency system shall be coordinated for an orderly
shutdown and the coordination study shall be submitted to the Department after selection
of the manufacturer. (240-12)
G
3.
Motor circuit protectors shall not be used as part of the a series combination interrupting
rating. (110-3, 93.0402)
G
4.
Series ratings shall not be used where
a.
Motors are connected on the load side of the higher-rated overcurrent device and
on the line side of the lower-rated overcurrent device; and
b.
The sum of the motor full-load currents exceeds 1 percent of the interrupting rating
of the lower-rated circuit breaker. (240-86)
CALCULATIONS
G
1.
Provide short circuit analysis including motor contribution and other current sources. Fuse
let-thru is not acceptable.(110-9&10, 93.0207)
G
3.
Provide the maximum full load motor(s) current contribution between the combination of
two overcurrent protection devices used in the series rating. (93.0207)
NOTES ON PLANS
G
1.
Service equipment shall be suitable for short circuit current available at its supply terminals.
The distribution system and equipment shall also meet this requirement. (110-9)
G
2.
If series combination ratings are used, provide a cautionary label to the series rated device
covers stating “ Caution - Series rated system ____________ A available. Identified
replacement component required.” (N.E.C. 110-22, 240-86)
G
3.
Indicate the series combination interrupting rating of the overcurrent devices. Clearly indicate
the system and combination voltage class. In a series rated connected system, the upstream
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protector shall be fully rated and the downstream protector is specified by the manufacturer.
(240-83(c), 240-86(a), 110-9, 93.0404, UL Recognized Directory)
G
4.
Overcurrent devices shall not be installed before approval of the coordination study by the
Electrical Plan Check. (240-12, 93.0104, 93.0206(b)9)
G
5.
All coordination studies shall bear the signature and stamp of a State of California registered
electrical engineer. (93.0206(a))
G
6.
Series combination ratings shall not be used where full selectivity between devices is required.
Example where such selectivity is required include (but not limited to):
a. Electrical systems which supply important loads such as fire pumps, fire alarm system,
smoke control systems, elevators, emergency lights, emergency communication systems,
cranes, hazardous area purging systems, sewage pump systems, etc.
b. Manufacturing or industrial processing facilities where loss of power can result in economic
loss due to production downtime, damage to equipment, or endangering the work place.
c. Hospitals where life support is critical. (240-12, 240-13, 240-86, 240-90, Art. 517)
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