Surge protection devices without overcurrent protection

Personally I would return it back to FuseBox and explain the reason.  Get a replacement from Navitas which has SPD type 2 with MCB and job done.  

The main issue here is the responsibility is with the designer and not really the installer.  Now in some smaller companies that may well be one and the same person.  Thus in that scenario they will normally rely in what the Manufacturer states HOWEVER and there is always an However or Caveat.  Some manufacturers are being lead by their marketing and sales department and the regulations and product specifications are somewhat slower to catchup.  A prime example of this would be battery storage and inverters in UK lofts.  Previously seen as OK by the marketing and sales department but when engineers start to discuss the issue and apply their engineer judgment then the industry is told that placement in the loft in unwise or a complete no-go.  There electrical industry I’m the UK is constantly evolving and thus so will the rules.

Back to the subject at hand.  Does the SPD really need an MCB?  In my opinion yes.  Some reason (not all reasons) listed below
 - MCB allows for safe isolation when the SPD needs replacing
 - MCB provides overcurrent protection for the SPD
 - MCB will be your fall back when the SPD fails due to fault or it gets to the end of it’s life cycle

For the real lowdown I would recommend "Kirsty at SPD".  Kirsty Johnson, Technical Sales Director at Surge Protection Devices (SPD), a company specialising in surge protection products. She has put out a lot of information on the internet and well worth at least 15 mins or anyone time.

Her linkedin profile is below

linkedin.com/in/kirsty-johnson-5a07ab71

Additional reference is one of the many Navitas videos by Will Winter

https://youtu.be/94tJ-lpo6rY?si=ydL0wgGmSCiObWPs

As others have said in the past.

Trust BUT verify

Back to the subject at hand.  Does the SPD really need an MCB?  In my opinion yes.  Some reason (not all reasons) listed below
 - MCB allows for safe isolation when the SPD needs replacing
 - MCB provides overcurrent protection for the SPD
 - MCB will be your fall back when the SPD fails due to fault or it gets to the end of it’s life cycle

On the other hand the MCB may "nuisance trip" - given the purpose of an SPD is to momentarily short-out L/N/PE - a simple thermal only device may be more reliable in that respect. Safe isolation can be done by other devices (a DP isolator might be somewhat better than a single pole MCB) and as long as there's overload protection built-in to the SPD aren't the other two points covered?

what about these? shop4electrical.co.uk/.../6693-wylex-rec2spd-18th-edition-standalone-rec-unit-with-100a-switch-disconnector-isolator-type-2-surge-protection-device-in-insulated-enclosure-5013601107127

    - Andy.

Would the SPD type 2 overload protection still work when the SPD reaches the end of it's lifecycle?

Would the SPD type 2 overload protection still work when the SPD fails due to fault?

Would the SPD type 2 overload protection still work when the SPD reaches the end of it's lifecycle?

Would the SPD type 2 overload protection still work when the SPD fails due to fault?

The fusible/ thermal  link inside the SPD is only there to operate at end of life  - the last act is to blow clear and isolate, rather than fail short.
And relying on a separate MCB has the weakness of not detecting the possible overheat associated with an steadily increasing leakage current degradation.
It is only fuse wire and a spring - if anything it will fail-safe early.

Mike

The fusible link inside the MCB

SPD?

   - Andy.

yup now edited. apologies.

yup now edited. apologies.