Xmas Special | Failed SPDs, Missing Protection & Why the MCB Still Matters

About this episode

The episode discusses the importance of dedicated overcurrent protection for Type 2 SPDs in electrical installations.

It’s the third Torque Up festive special, but this year the tinsel takes a back seat and the lads go deep on the technical question hitting installs up and down the country: Can a Type 2 SPD rely on an upstream service fuse for overcurrent protection, or must it have a dedicated protective device within the installer’s control? The sparks’ sentiment in the room is clear: manufacturer thermal ratings are part of the product design , but they do not guarantee compliance under BS 7671 if there is no dedicated, testable, local overcurrent protective device protecting the SPD as part of the installation. What you’ll take from this episode: ● A thermal disconnection flag is a failsafe , not overcurrent protection ● The upstream DNO fuse is not dedicated to the SPD circuit , and has unknown characteristics for selectivity and verification ● Install design must meet the literal minimums of BS 7671 installers can verify and test ● Why Navitas kept the 32A MCB in their SPD consumer unit design when others removed it ● The wider industry frustration: installs previously passed are now being flagged for missing protection ● Why electricians care more about predictable disconnection than tidy…

People in this episode

Host: William Winter

Topics covered

• overcurrent protection
• Type 2 SPD
• BS 7671 compliance
• electrical installations
• industry standards

Keywords

• Type 2 SPD
• overcurrent protection
• thermal disconnection
• DNO fuse
• BS 7671
• electrical installations
• Navitas
• MCB

Mentioned in this episode

Organizations: Navitas

Books & works: BS 7671:2018+A

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