SPD for Distribution Board
Choose the right surge protective device for main distribution boards, sub-distribution boards, consumer units, and industrial electrical panels. This page helps buyers compare Type 2 and Type 1+2 DIN rail SPDs, pole configurations, grounding requirements, and installation positions.
Réponse rapide : Most sub-distribution boards use a Type 2 DIN rail SPD. Main incoming distribution boards may need a Type 1+2 SPD when the building has higher lightning exposure, an external lightning protection system, or an overhead supply. The SPD must match the AC voltage, earthing system, phase configuration, surge rating, and backup protection requirement.
Which SPD should be used in each distribution board?
Distribution board SPD selection starts with the board position. A main incoming board, sub-board, consumer unit, and industrial control panel do not always need the same SPD type.
| Board Position | Recommended SPD | Application typique | Key Decision Point |
|---|---|---|---|
| Main distribution board / MDB | Type 1+2 SPD or Type 2 SPD | Building incoming panel, main switchboard, service entrance | Use Type 1+2 if lightning exposure, external LPS, or overhead supply risk is present. |
| Tableau de sous-distribution | Parafoudre DIN rail Type 2 | Workshop DB, office floor DB, machine area panel, electrical room | Most common distribution board SPD choice for secondary protection. |
| Consumer unit | SPD de type 2 1P+N ou 2P | Residential and small commercial AC boards | Match single-phase wiring, neutral protection, and local installation practice. |
| Three-phase distribution board | 3P, 3P+N, or 4P Type 2 SPD | Commercial buildings, factories, pumps, HVAC, industrial loads | Match phase system, neutral structure, and earthing system. |
| Panneau de contrôle industriel | Type 2 SPD, sometimes with downstream Type 3 | PLC cabinets, automation panels, control rooms | Use lower Up and short wiring to protect sensitive electronics. |
When is Type 2 enough, and when do you need Type 1+2?
ONCCY gives simple kA recommendations, but a stronger distribution board page should explain the decision path. The SPD type is not selected only by breaker size. It also depends on board position, lightning risk, incoming line type, earthing, and project requirements.
Use Type 2 SPD for most sub-distribution boards
Type 2 DIN rail SPDs are typically used for secondary surge protection in downstream distribution boards, commercial panels, machine panels, and consumer units. They are tested with the 8/20 μs surge waveform and are used to limit transient overvoltage from indirect lightning and switching surges.
Use Type 1+2 SPD for main incoming boards when required
A Type 1+2 SPD is used when the distribution board is at the incoming side of the installation and may need to discharge partial lightning current. This is common for exposed buildings, external lightning protection systems, or overhead power supply conditions.
How to size an SPD for a distribution board
This page uses a safer engineering logic than a simple “breaker amp = SPD kA” rule. The table below gives a practical buyer-friendly direction without making the selection too absolute.
| Élément de sélection. | What to Check | Practical Direction |
|---|---|---|
| Type de DOCUP | Type 1+2 or Type 2 | Main incoming board with high exposure may require Type 1+2. Sub-distribution boards commonly use Type 2. |
| Uc | Tension de fonctionnement maximale continue | Match the AC system voltage and earthing arrangement. Do not use DC SPD for normal AC distribution boards. |
| En | Courant de décharge nominal | Common Type 2 DB SPDs are often selected around 20kA or 40kA In, depending on exposure and specification. |
| Imax | Courant de décharge maximum | Higher Imax may be chosen for larger panels, harsher surge environments, or project requirements. |
| Iimp | Lightning impulse current for Type 1 / Type 1+2 | Relevant for incoming distribution boards where lightning current handling is required. |
| Haut de la page | Niveau de protection de la tension | Lower Up helps reduce residual stress on downstream equipment, especially electronics and control devices. |
| Protection de secours | Fuse or breaker coordination | Follow the SPD datasheet for maximum backup fuse, short-circuit rating, and installation method. |
| Remote signal | Status monitoring contact | Useful for commercial, industrial, and OEM boards that require maintenance visibility. |
Single-phase and three-phase distribution board SPD selection
This is where our page can clearly beat generic SPD size articles. Distribution board buyers often need to know whether to choose 1P+N, 2P, 3P, 3P+N, or 4P.
Single-phase board
Common for residential and small commercial boards. Typical SPD options include 1P+N or 2P Type 2 SPD, depending on wiring system and local installation practice.
Three-phase board without neutral protection
Some three-phase systems use 3P SPD configurations. This should match the earthing system and project wiring design.
Three-phase board with neutral
3P+N or 4P SPD options are common where neutral protection is required. This is often important for commercial and industrial distribution boards.
Earthing system affects distribution board SPD selection
A good SPD page should not ignore grounding. The earthing system affects protection mode, pole configuration, neutral protection, and backup design.
| Earthing System | Common Selection Concern | Buyer Note |
|---|---|---|
| TN-S | Separate neutral and PE conductors | Common in commercial and industrial installations. Match SPD mode to the system design. |
| TN-C-S | PEN conductor separated into N and PE downstream | Confirm where the SPD is installed relative to the separation point. |
| TT | Earth fault and neutral-to-earth protection require care | Neutral protection and RCD coordination may need special attention. |
| IT | Insulated or impedance-earthed system | Final SPD choice should follow project specification and system design. |
Where should the SPD be installed in a distribution board?
SPD performance is affected by wiring length and layout. The device should be placed where it can divert surge current to earth with the shortest practical connection path.
-
1
Install close to the incoming side.
Place the SPD near the main switch, incoming breaker, or supply entry point when board layout allows. -
2
Keep wires short and straight.
Long leads increase residual voltage during a surge. Avoid unnecessary loops and sharp routing. -
3
Use proper PE connection.
The SPD must be connected to a reliable earth bar with suitable conductor sizing. -
4
Check backup protection.
Use the fuse or breaker rating recommended in the SPD datasheet.
-
5
Do not mix AC and DC SPD.
AC distribution boards need AC-rated SPDs. DC/PV SPDs are for photovoltaic strings, DC combiner boxes, and DC circuits. -
6
Check RCD coordination.
SPD position relative to RCDs depends on board design, earthing system, and local rules. -
7
Leave enough DIN rail space.
Confirm module width, wiring space, and maintenance access before ordering. -
8
Use remote signal when needed.
Commercial and industrial projects may require SPD status monitoring.
Recommended LEEYEE SPDs for distribution board applications
LEEYEE is a specialized surge protection and low-voltage protection supplier, trusted for solar PV, power distribution, telecom, industrial, and OEM applications. CNSPD is LEEYEE’s surge protection-focused brand platform.
Type 2 DIN Rail SPD
The most common choice for sub-distribution boards, consumer units, commercial panels, and general AC distribution protection.
- For secondary surge protection
- Single-phase and three-phase options
- Pluggable module options available
Type 1+2 DIN Rail SPD
Used where the main distribution board may need combined lightning current and surge protection.
- For exposed incoming panels
- Useful before downstream Type 2 SPD
- Suitable for higher-risk projects
DIN Rail Surge Protector
Compare AC, DC, Type 2, and Type 1+2 DIN rail surge protectors for distribution boards, control panels, solar systems, and OEM assemblies.
- DIN rail mounted SPD family
- AC and DC options
- OEM and private label support
Send these details for a faster SPD recommendation
This checklist makes the page stronger than a normal blog post because it helps real buyers move from reading to selection.
SPD for distribution board FAQ
These FAQs are written in a direct answer format so search engines and AI systems can easily understand the page intent.
What type of SPD is used in a distribution board?
Most sub-distribution boards use a Type 2 DIN rail SPD. Main incoming distribution boards may need a Type 1+2 SPD if the building has higher lightning exposure, an external lightning protection system, or an overhead power supply.
Is Type 2 SPD enough for a distribution board?
Type 2 SPD is enough for many sub-distribution boards and consumer units. However, if the board is at the service entrance or exposed to higher lightning current risk, Type 1+2 protection may be required.
Where should an SPD be installed in a distribution board?
The SPD is usually installed close to the incoming side of the board and connected in parallel to the supply. The connection to live conductors and earth should be short and straight.
What kA rating should I choose for a distribution board SPD?
Many Type 2 distribution board SPDs are selected around 20kA or 40kA In, with higher Imax options used for larger panels or harsher surge environments. Final selection should also consider voltage, earthing, short-circuit rating, backup protection, and local code.
What is the difference between Type 1+2 SPD and Type 2 SPD?
Type 1+2 SPD can handle lightning impulse current and is commonly used at incoming boards when lightning exposure is higher. Type 2 SPD is used for secondary surge protection in sub-distribution boards and downstream panels.
Can I use a DC SPD in an AC distribution board?
No. AC distribution boards should use AC-rated SPDs. DC SPDs are designed for PV strings, battery systems, DC combiner boxes, and other DC circuits.
What information is needed to choose the right SPD?
Confirm the board position, AC voltage, phase system, earthing system, SPD type, pole configuration, surge rating, backup protection, and whether remote signal monitoring is needed.
Need the right SPD for your distribution board?
Send your board type, voltage, phase system, earthing system, and project market. LEEYEE can help you select a suitable DIN rail SPD for residential, commercial, industrial, or OEM distribution board applications.