1. Why facade lighting creates multiple surge entry paths

A facade system may include an AC feeder, several power supplies, long 24V runs, a DMX controller, data splitters, outdoor control cable, metal supports and building earth. Lightning electromagnetic impulse can couple into more than the utility line. IEC 62305-4 treats surge protection as a system of design, installation, inspection, maintenance and testing measures [S1]. Therefore, a single cabinet SPD is a starting point, not proof that remote equipment terminals see an acceptable residual voltage.

2. Three protection layers must not be confused

3. The mechanism: clamping is only half the circuit

An SPD limits voltage by conducting surge current away from the protected path [S2]. The diverted current still needs a low-impedance route. Any conductor inductance adds voltage during a fast current change. The governing relationship is:

Long looping SPD leads, shared earth paths and separation between the SPD and the protected terminal can therefore undermine a device selected only by catalogue rating. Final placement and bonding must be coordinated by the electrical designer.

4. Worked interface-count and failure-domain example

Illustrative system: 24 wall washers, each published product reference rated 36W at DC24V [S5]. Eight fixtures are assigned to each of three power supplies.

• Total nominal fixture load: 24 × 36W = 864W.
• Load per eight-fixture group: 8 × 36W = 288W.
• Ideal DC load current per group: 288W ÷ 24V = 12A, before cable loss, conversion margin and project derating.
• Conductive interfaces to audit: 1 incoming AC feed + 3 power-supply AC inputs + 3 exposed DC branches + 1 controller supply + 3 outdoor DMX branch entries = 11 interfaces.

The count does not mean “buy 11 identical SPDs.” It forces every crossing to be classified. If one unprotected DC or DMX branch reaches a remote facade zone, the system can still have a bypass path. Required device count and location remain 待确认 after the actual one-line diagram, cable routes and equipotential zones are reviewed.

5. A seven-step coordination workflow

1. Draw boundaries: mark utility entry, cabinet, building-to-outdoor transitions, roof/ground changes and remote metalwork.
2. Inventory conductors: AC L/N/PE, DC positive/negative, DMX pair/reference/shield and any network cable.
3. Record maximum normal conditions: system voltage, polarity, frequency, branch current and fault conditions.
4. Obtain equipment data: declared surge withstand for power supply, controller, splitter and fixture. Unknown means 待确认.
5. Select the correct SPD category: do not place an AC-only SPD on DMX or a data SPD on a power circuit [S2][S4].
6. Coordinate protection level and disconnecting: use IEC selection principles and local electrical rules [S3].
7. Verify installation: inspect lead length/routing, bonding, enclosure, status indication, replaceability and maintenance records.

6. Product reference: what the page proves and what it does not

LIKELIGHT publishes L-W-10036-DMX as 36W, DC24V, RGB and DMX512 [S5]. Those facts support the load example and interface map. They do not establish the model's surge immunity, internal protection circuit, connector pin withstand, insulation coordination or suitability for a particular lightning protection zone. Obtain the approved datasheet/test report before specifying SPD protection levels.

7. When not to choose or approve the proposed protection

• The proposal gives only an SPD current rating, with no system voltage, protection level, device class/test basis or fault coordination.
• The same protection device is proposed for AC, 24V DC and DMX without interface-specific documentation.
• The SPD is installed far from the protected terminal with long looped conductors, but added lead voltage is not reviewed.
• The DMX protector's capacitance/bandwidth and signal compatibility are unknown.
• The fixture or controller surge withstand is unknown, so coordination cannot be demonstrated.
• There is no status inspection, replacement plan or event/maintenance record.
• The project lacks a qualified electrical/lightning-protection review. This article is not a substitute for one.

8. Evidence ledger

9. FAQ

Does a panel SPD protect the remote 24V fixtures automatically?

No automatic conclusion is possible. Cable routing, boundaries, power-supply behavior, terminal withstand and downstream protection must be reviewed.

Can one SPD protect AC power and DMX?

Not unless it is a documented multiservice solution suitable for both interfaces. IEC treats AC and signalling protection in different application standards [S2][S4].

Should an SPD be installed at both cable ends?

It depends on protection zones, cable exposure, equipment at both ends and bonding. The one-line diagram and site risk assessment are required.

Why does lead length matter?

Fast-changing current through connection inductance adds voltage according to V=L×di/dt.

How is an SPD maintained?

Follow its manufacturer status indication and replacement instructions, and include inspection/maintenance in the project plan [S1].

Who authored and reviewed this guide?

Author: LikeLight Tom, Operations. Technical reviewer: 待确认.