solar pv and automatic disconection of supply ADS

[sime27]

forget type B rcd's at minute
do we have to use a .30ma rcd to meet 17th edition requirments of .4 seconds disconection times for domestic solar pv system (16amp) even if cable is surface mounted outside in conduit ?


regardless of Zs as its normally low anyways to gain 1% volt drop.
but under 17th edition does every circuit below 32amp have to trip in .4 seconds ?
which will need a rcd am i right ?

 

[BruceB]

1. No, a 30mA rcd is not mandated. Mcbs can meet that disconnection time with suitably low Zs. Which reg do you think would require a rcd?

2. No. Distribution circuits have a 5s (TN) or 1s(TT) disconnection time. 411.3.2.3 and 411.3.2.4 refer.

Regards
Bruce

 

[sime27]

I thought pv circuit would still be classed as a final circuit not a distribution as in night hrs its not Distributing anything .
I thought its a outdoor supply which would require a 30ma rcd and its below 32amp which would need at .4 seconds disconection time

 

[SolarCity]

The AC side of the circuit is indoors anyway.

The DC side of the system, which is mainly outdoors, doesn't require ADS.

 

[sime27]

So do you normally protect your pv systems with a rcd or not ?
i have been fitting a new 2way CU with a 63amp 30ma main switch then a 16a 60898 mcb
i could save time and money if no need for a rcd everytime

 

[BruceB]

I thought pv circuit would still be classed as a final circuit not a distribution as in night hrs its not Distributing anything .

When there is a power cut and the main supply stops supplying power, you do not suddenly deem it to be a final circuit. It will not be an issue anyway, the normal mcb on a pv circuit will disconnect within 0.4s in the event of a fault

I thought its a outdoor supply which would require a 30ma rcd and its below 32amp which would need at .4 seconds disconection time

Again, which reg are you thinking of?

Regards
Bruce

 

[sime27]

special locations

 

[grandfortune]

its pretty hard not to RCD a circuit now, why would you not want to??

 

[SolarCity]

Nuisance tripping

 

[grandfortune]

does that happen alot?, and could it be weeks before you notice?

 

[dansk]

Sime27 just have a read of the OSG for quick ref to RCD protection, unless the invert needs it, or the cable is buried less than 50mm then 30ma not needed. Just because it's the "17th" it doesnt mean everything needs RCD.