BANG!

[pc1966]

Coincidences youtubing 25kA testing yesterday.
Selling class J fuses !
(The arcing noises used to promote -Electrician things - does bug me)

That is an impressive demo.

Thankfully the PFC on our local bus-bar chamber is just under 12kA and we are using fuses are our primary OCPD so a little less sphincter clenching when powering on via the big leaver...

 

[R-fur]

So it looks like having overcurrent protection on a SPD is a good idea, but that means an extra MCB in the board with cost and space considerations. Is there any reason why the SPD could not be doubled up with say a shower?

 

[Julie.]

So it looks like having overcurrent protection on a SPD is a good idea, but that means an extra MCB in the board with cost and space considerations. Is there any reason why the SPD could not be doubled up with say a shower?

There are a few issues, the first is that going via additional impedance can reduce the effectiveness of the spd, but as many others do go via a MCB it does show this is manageable

The second is really about availability, if the shower circuit is off for any reason, then the spd is also out of circuit

The big one though is that almost all circuits these days need rcd protection, and the circuit to a spd must not!

 

[R-fur]

Fair enough, I forgot about the RCD issue. If its a choice of no MCB or doubling up with a submain I think I would prefer to double up.

 

[pc1966]

Usually incomer delay RCDs are rated for kA sized surges, but not all downstream types are.