Following a few debates here, and in other places about whether over-current protection is required for SPDs, BEAMA issued a statement in January saying, extra OCPDs are not always required for SPDs. Full details in the link below.
As an aside, I do check the BEAMA site semi-regularly, but didnt spot this one until I had an email from Dehn yesterday.
I wonder what the suppliers'/DNOs' position is on this. How often do SPDs go short circuit?
How often do SPDs go short circuit?
Even if they do, 99% of the time it should still be dealt with by the SPD's own internal protection - it's only in rare circumstances (akin to faults that exceed breaking capacity of MCBs) that the DNO's fuse would be called upon for backup protection.
- Andy.
Thanks Alan for posting this. I also first heard about it in the Dehn circular yesterday. One to slip between the pages of the brand new orange book which arrived yesterday?!
I wonder what the suppliers'/DNOs' position is on this.
If the ENA are involved then assumedly the individual DNOs are okay with it?! Or at least a majority are.
What happens when the SPD type 2 expires and needs replacement, possible exposed parts when the cartridge is removed?
What happens when the SPD type 2 expires and needs replacement, and the cartridge CAN NOT be removed due the effect of thermal damage?
What happens when people don't know the difference between an
SPD Type 1?
SPD Type 2?
SPD Type 3?
The ENA/BEAMA statement has a number of conditions on which the permision is contingent, one of which being that the "SPD does not require withrawal of the DNO cut-out for its replacement or maintenance". How that is achieved (provision of a means of isolation, one assumes, if the cartridge exposes live parts) is left to the installer.
As for not knowing the difference between type 1/2/3... that risk isn't changed by allowing the DNO cut-out fuse to be the OCPD.
What happens when the SPD type 2 expires and needs replacement, possible exposed parts when the cartridge is removed?
As the guidance said - "The SPD does not require withdrawal of the DNO cut-out fuse for its replacement or maintenance." All the plug-in SPDs I've seen mate with bases that provide at least finger-proof protection to live parts.
What happens when the SPD type 2 expires and needs replacement, and the cartridge CAN NOT be removed due the effect of thermal damage?
I guess the same as happens when there's thermal damage to any part upstream of outgoing devices - switch off if you can (just because there's no OPD doesn't mean you can't use the main switch or supplier's isolator) - failing that call out the DNO.
What happens when people don't know the difference between an
SPD Type 1?
SPD Type 2?
SPD Type 3?
They shouldn't be messing with things they don't understand?? Most SPD cartridges are keyed so the wrong types can't be inserted into a correctly installed base - mostly to stop L-N types (MOV) being used in N-PE situations (gas discharge), but I suspect will stop most such mistakes.
- Andy.
To be honest I think there SHOULD be a OCPD for a Type 2 SPD in the CU (Consumer Unit) and not relying on the DNO/DSO cut out main fuse due to the following
It provides OCPD protect to the SPD
It provide a means of safe isolation/Authoritative control for replacement or servicing as required in many place by BS7671
eg. Isolation and Switching (Part 5): Every installation must have a main switch to cut all live conductors
eg. Maintenance Isolation: Devices must be provided to allow safe disconnection of electrical equipment for maintenance, such as local isolators for motors or appliances
Thus an OCPD is reasonably practicable and sound engineering judgement. If not this will turn into another whole debacle of single insulated cables in a meter box/cabinet being allowed and no EICR code. Remember we need to use our engineering judgement
To be honest I think there SHOULD be a OCPD for a Type 2 SPD in the CU (Consumer Unit) and not relying on the DNO/DSO cut out main fuse due to the following
At least they have not been banned, so mine is staying where it is.
To be honest I think there SHOULD be a OCPD for a Type 2 SPD in the CU (Consumer Unit) and not relying on the DNO/DSO cut out main fuse due to the following
At least they have not been banned, so mine is staying where it is.
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