Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Surge Protective Devices
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## The Contractor shall coordinate the SPD ground and neutral connections with [[sync/grounding-and-bonding]].
−## The Contractor shall coordinate SPD short-circuit current ratings and mounting provisions with the panelboards, switchboards, and switchgear that house them, per [[sync/low-voltage-panelboards]], [[sync/low-voltage-switchboards]], and [[sync/low-voltage-switchgear]].
+## The Contractor shall coordinate SPD short-circuit current ratings and mounting provisions with the panelboards, switchboards, and switchgear that house them, per [[sync/panelboards]], [[sync/low-voltage-switchboards]], and [[sync/low-voltage-switchgear]].
## An SPD is one element of a coordinated overvoltage-protection strategy, not a standalone product; its value depends on correct type selection, correct voltage and mode configuration, coordinated cascading between stages, and short connecting conductors. {note}
## A surge protective device is the modern term for what was historically called a transient voltage surge suppressor (TVSS); the two terms describe the same device, and UL 1449 governs both. {note}
−## Where a lightning protection system is installed, the SPD work shall be coordinated with it, but the air terminals, down conductors, and bonding of the lightning protection system are a separate scope covered by [[sync/lightning-protection]]. {note}
+## Where a lightning protection system is installed, the SPD work shall be coordinated with it, but the air terminals, down conductors, and bonding of the lightning protection system are a separate scope covered by [[sync/lightning-protection]].
# Referenced Standards {toc}
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- "Project SPD schedule showing coordinated stages"
- "Manufacturer installation instructions"
−default: "UL 1449 listing (VPR per mode, In rating, SCCR)"
+default:
+ - "Product data with Type, system voltage, modes, and mounting"
+ - "UL 1449 listing (VPR per mode, In rating, SCCR)"
+ - "Per-phase / per-mode surge current capacity"
+ - "Wiring diagram with recommended and maximum lead lengths"
+ - "Project SPD schedule showing coordinated stages"
+ - "Manufacturer installation instructions"
```
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### SPD installation shall be performed by electricians experienced in connecting surge protective devices and supervised by a licensed electrical contractor.
−### The installer shall be familiar with the lead-length and routing requirements of this standard, because correct installation is decisive for SPD performance. {note}
+### The installer shall be familiar with the lead-length and routing requirements of this standard, because correct installation is decisive for SPD performance.
# Environmental and Service Conditions {toc}
−## An SPD shall be suitable for the electrical system, ambient conditions, and enclosure environment at its point of installation. {note}
+## An SPD shall be suitable for the electrical system, ambient conditions, and enclosure environment at its point of installation.
## System Voltage and Configuration {toc}
−### The SPD shall be configured for the nominal system voltage and grounding configuration of the circuit it protects.
+### The SPD shall be configured for the nominal system voltage and grounding configuration of the circuit it protects, as indicated in the datasheet.
−### An SPD configured for one system voltage or grounding arrangement shall not be applied to a different one.
−
```datasheet
label: System Voltage and Configuration
type: select
+drawing_ref: "one-line diagram"
options:
- "208Y/120V, 3Φ 4-wire (solidly grounded wye)"
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- "240V delta, 3Φ 3-wire"
- "600Y/347V, 3Φ 4-wire"
−default: "208Y/120V, 3Φ 4-wire (solidly grounded wye)"
+default: deferred
```
−### Applying a wye-configured SPD to a delta or otherwise ungrounded system places full line-to-line voltage across the line-to-ground modes, which the SPD is not rated to sustain and which causes premature failure; the maximum continuous operating voltage must be matched to the actual grounding arrangement. {note}
+### An SPD configured for one system voltage or grounding arrangement shall not be applied to a different one.
+### Applying a wye-configured SPD to a delta or otherwise ungrounded system places full line-to-line voltage across the line-to-ground modes, which the SPD is not rated to sustain and which causes premature failure; the maximum continuous operating voltage must be matched to the actual grounding arrangement.
+
## Enclosure and Ambient {toc}
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```datasheet
label: Maximum Ambient Temperature
−type: select
+type: range
unit: °C
options:
− - "40°C (standard rating)"
− - "50°C"
− - "55°C"
−default: "40°C (standard rating)"
+ min: 40
+ max: 55
+ setpoints: [40, 50, 55]
+default: 40
```
+### 40°C is the standard ambient rating for surge protective devices; a higher-ambient device shall be selected only where the installed location exceeds that temperature.
+
### An externally mounted SPD enclosure shall match or exceed the environmental rating of the equipment it serves.
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## UL 1449 classifies permanently connected and point-of-use SPDs into Types that define where the device may be installed relative to the service disconnect. {note}
−## Type 1 SPDs are permitted on the line (supply) side of the service-equipment overcurrent device, and also on the load side; Type 2 SPDs are permitted only on the load side of the first overcurrent device; Type 3 SPDs are point-of-utilization devices installed at least 10 m (30 ft) of conductor length from the service. {note}
+## Type 1 SPDs are permitted on the line (supply) side of the service-equipment overcurrent device, and also on the load side; Type 2 SPDs are permitted only on the load side of the first overcurrent device; Type 3 SPDs are point-of-utilization devices installed at least 30 ft (10 m) of conductor length from the service. {note}
## Type 1 is the only Type permitted to connect on the supply side of the service disconnecting means. {note}
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type: radio
options:
− - "Type 1 (line side or load side of service disconnect)"
− - "Type 2 (load side of service disconnect only)"
−default: "Type 2 (load side of service disconnect only)"
+ - "Type 1 (line or load side of the service disconnect)"
+ - "Type 2 (load side of the service disconnect)"
+default: "Type 2 (load side of the service disconnect)"
```
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options:
- "Provided at designated distribution and sub-panels"
− - "Not provided (service-entrance SPD only)"
+ - "Not provided (service-entrance SPD alone)"
default: "Provided at designated distribution and sub-panels"
```
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### Where required to protect specific sensitive equipment, a Type 3 SPD shall be installed at or near the point of use.
−### A Type 3 SPD shall be installed at least 10 m (30 ft) of conductor distance from the service or separately derived system disconnect, in accordance with its listing and NFPA 70 242.16.
+### A Type 3 SPD shall be installed at least 30 ft (10 m) of conductor distance from the service or separately derived system disconnect, in accordance with its listing and NFPA 70 242.16.
### The conductor distance required for a Type 3 device provides the series impedance that decouples it from the upstream SPD and allows the two to coordinate rather than fight over the same surge. {note}
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# Electrical Ratings {toc}
−## The electrical ratings determine whether an SPD actually protects the connected load; they shall be selected together and coordinated with the system and the host equipment. {note}
+## The electrical ratings determine whether an SPD actually protects the connected load; they shall be selected together and coordinated with the system and the host equipment.
## Voltage Protection Rating {toc}
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### The VPR is the single most important protection metric because it is the voltage that actually reaches the connected equipment; a lower VPR provides better protection. {note}
+### The SPD VPR for each protected mode shall not exceed the values selected for the project.
+
```datasheet
label: Maximum VPR — Line-to-Neutral (208Y/120 or 240/120)
−type: select
+type: range
unit: V
options:
− - "330 V"
− - "400 V"
− - "500 V"
− - "600 V"
− - "700 V"
− - "800 V"
−default: "700 V"
+ min: 330
+ max: 800
+ setpoints: [330, 400, 500, 600, 700, 800]
+default: 700
```
```datasheet
label: Maximum VPR — Line-to-Ground (208Y/120 or 240/120)
−type: select
+type: range
unit: V
options:
− - "400 V"
− - "500 V"
− - "600 V"
− - "700 V"
− - "800 V"
− - "900 V"
−default: "800 V"
+ min: 400
+ max: 900
+ setpoints: [400, 500, 600, 700, 800, 900]
+default: 800
```
−### The SPD VPR for each protected mode shall not exceed the values selected for the project.
+### The Contractor shall not substitute a high surge-current device with a poor VPR for a device with the specified VPR; surge current capacity governs durability, while VPR governs protection.
−### The Contractor shall not substitute a high surge-current device with a poor VPR for a device with the specified VPR; surge current capacity governs durability, while VPR governs protection. {note}
−
### Specifying a high kilo-amp surge rating while ignoring VPR is the most common SPD specification error and yields a durable device that passes through damaging voltage to the load. {note}
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type: radio
options:
− - "Manufacturer standard MCOV for the selected system voltage"
+ - "Standard MCOV matched to the system voltage and grounding configuration"
- "Elevated MCOV (for systems with chronic overvoltage or voltage swell)"
−default: "Manufacturer standard MCOV for the selected system voltage"
+default: "Standard MCOV matched to the system voltage and grounding configuration"
```
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### The nominal discharge current (In) is the peak 8/20 µs current the SPD can survive for 15 surges and remain functional, and it is a measure of the device's durability over repeated events. {note}
+### The service-entrance SPD shall have a nominal discharge current of not less than 20 kA, the distribution SPD not less than 10 kA, and the point-of-use SPD not less than 3 kA, consistent with IEEE C62.72 application guidance for the respective location categories.
+
```datasheet
label: Nominal Discharge Current (In) — Service Entrance
−type: select
+type: range
unit: kA
options:
− - "10 kA"
− - "20 kA"
−default: "20 kA"
+ min: 10
+ max: 20
+ setpoints: [10, 20]
+default: 20
```
```datasheet
label: Nominal Discharge Current (In) — Distribution
−type: select
+type: range
unit: kA
options:
− - "3 kA"
− - "5 kA"
− - "10 kA"
− - "20 kA"
−default: "10 kA"
+ min: 3
+ max: 20
+ setpoints: [3, 5, 10, 20]
+default: 10
```
```datasheet
label: Nominal Discharge Current (In) — Point of Use
−type: select
+type: range
unit: kA
options:
− - "3 kA"
− - "5 kA"
− - "10 kA"
−default: "3 kA"
+ min: 3
+ max: 10
+ setpoints: [3, 5, 10]
+default: 3
```
−### The service-entrance SPD shall have a nominal discharge current of not less than 20 kA, the distribution SPD not less than 10 kA, and the point-of-use SPD not less than 3 kA, consistent with IEEE C62.72 application guidance for the respective location categories.
−
### The In rating is distinct from the one-time surge current capacity; In describes how many repeated surges the device tolerates while continuing to protect, which is what determines service life in a real surge environment. {note}
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```datasheet
label: Surge Current Capacity — Service Entrance (per phase)
−type: select
+type: range
unit: kA
options:
− - "50 kA"
− - "80 kA"
− - "100 kA"
− - "120 kA"
− - "160 kA"
− - "200 kA"
− - "240 kA"
− - "300 kA"
− - "400 kA"
−default: "200 kA"
+ min: 50
+ max: 400
+ setpoints: [50, 80, 100, 120, 160, 200, 240, 300, 400]
+default: 200
```
```datasheet
label: Surge Current Capacity — Distribution Panel (per phase)
−type: select
+type: range
unit: kA
options:
− - "50 kA"
− - "80 kA"
− - "100 kA"
− - "120 kA"
− - "160 kA"
−default: "100 kA"
+ min: 50
+ max: 160
+ setpoints: [50, 80, 100, 120, 160]
+default: 100
```
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```datasheet
label: SPD Short-Circuit Current Rating (SCCR)
−type: select
+type: range
unit: kAIC
drawing_ref: "one-line diagram"
options:
− - "10 kAIC"
− - "22 kAIC"
− - "25 kAIC"
− - "42 kAIC"
− - "65 kAIC"
− - "100 kAIC"
− - "200 kAIC"
+ min: 10
+ max: 200
+ setpoints: [10, 22, 25, 42, 65, 100, 200]
default: deferred
```
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## An all-mode SPD provides suppression in every available mode, while a partial-mode SPD provides only some modes, typically omitting L-G or N-G. {note}
+## SPDs shall provide all-mode protection unless the contract documents specifically permit a reduced mode set.
+
```datasheet
label: Protection Modes
…6 unchanged lines
```
−## SPDs shall provide all-mode protection unless the contract documents specifically permit a reduced mode set.
−
## An all-mode device suppresses both common-mode (to ground) and normal-mode (between conductors) surges, whereas a partial-mode device leaves the unprotected modes to pass surge energy to the load. {note}
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### Omission of the N-G mode on a separately derived system is a frequent and consequential error, because the local neutral-to-ground bond at the derived source means common-mode surges are not otherwise suppressed and pass directly to downstream equipment. {note}
−### The Contractor shall coordinate the bonding of the separately derived system, including the system bonding jumper and grounding electrode connection, with [[sync/grounding-and-bonding]]. {note}
+### The Contractor shall coordinate the bonding of the separately derived system, including the system bonding jumper and grounding electrode connection, with [[sync/grounding-and-bonding]].
# Construction and Components {toc}
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### The SPD shall include integral overcurrent protection or disconnection consistent with its UL 1449 listing.
−### The thermal disconnect is the core end-of-life safety mechanism of a modern SPD; a metal-oxide varistor that has degraded from repeated surges draws increasing current and must be disconnected before it fails thermally. {note}
+### The thermal disconnect is the core end-of-life safety mechanism of a modern SPD; a metal-oxide varistor that has degraded from repeated surges draws increasing current and must be disconnected before it fails thermally.
## Status Indication {toc}
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### A Type 1 SPD does not require an external overcurrent device, because its disconnection means is internal to the listed device. {note}
−### Where the manufacturer's instructions specify or permit an external overcurrent device for a Type 2 SPD, it shall be sized per those instructions; an oversized device may fail to clear a degraded SPD. {note}
+### Where the manufacturer's instructions specify or permit an external overcurrent device for a Type 2 SPD, it shall be sized per those instructions; an oversized device may fail to clear a degraded SPD.
# Testing {toc}
…19 unchanged lines
- "Audible alarm function confirmed (where provided)"
- "Connecting conductor lead length verified within limit"
−default: "Per-phase status indication confirmed healthy"
+default:
+ - "Per-phase status indication confirmed healthy"
+ - "Connecting conductor lead length verified within limit"
```
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## Where an SPD is required for compliance with NFPA 70 230.67, the service equipment shall be marked to indicate that the SPD is part of the service and shall not be re-energized without it.
−## The meaning of the status indicators and the module replacement procedure shall be available at the device, either on a label or in the operation and maintenance data. {note}
+## The meaning of the status indicators and the module replacement procedure shall be available at the device, either on a label or in the operation and maintenance data.
# Delivery, Storage, and Handling {toc}
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## SPDs shall be stored indoors in a clean, dry location and protected from moisture, corrosive atmospheres, and physical damage until installed.
−## SPDs shall not be installed if their enclosures or modules show evidence of impact, moisture intrusion, or other damage. {note}
+## SPDs shall not be installed if their enclosures or modules show evidence of impact, moisture intrusion, or other damage.
# Warranty {toc}
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- "5 years from substantial completion"
- "10 years from substantial completion"
− - "Manufacturer's standard limited warranty"
+ - "20 years from substantial completion"
default: "10 years from substantial completion"
```
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## The Contractor shall warrant the installation, including the connecting conductor routing and the correct status indication of each device, for the project warranty period.
−## Where a manufacturer offers a connected-equipment protection guarantee, it may be required, with the understanding that such guarantees carry conditions on installation and coordination that the Contractor shall satisfy. {note}
+## Where a manufacturer offers a connected-equipment protection guarantee, it may be required, with the understanding that such guarantees carry conditions on installation and coordination that the Contractor shall satisfy.
# Spare Parts {toc}
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## Stocking spare modules allows a depleted SPD to be restored to service quickly after a major surge event, rather than waiting on procurement while equipment is unprotected. {note}