17th Edition (C&G 2382) Couple of questions, help

[ADS]

Hi Jud,

Sorry, mate, it was the big red writing in the middle of my quoted post - It seemed like you were shouting at me.

When an RCD is used to comply with the disconnection times in table 41.1 (pg 46), a current of 2 x I delta N is typically used. - see Note 2 underneath the table.

If you then look at Table 3A (pg 243), in the second column, it gives the time that a 30mA RCD will trip in, at 60mA (2 x I delta N), as 150mS (0.15 mS)

As we require a disconnection time of 0.07 for our example, this is to slow.

So we go to the next column along - 150mA (5 x I delta N), which gives a trip time of 40 mS (as we know).

As this is within our disconnection time (70mS), then this is the figure we must use.

 

[JUD]

Hi Jud,Sorry, mate, it was the big red writing in the middle of my quoted post - It seemed like you were shouting at me.

When an RCD is used to comply with the disconnection times in table 41.1 (pg 46), a current of 2 x I delta N is typically used. - see Note 2 underneath the table.

If you then look at Table 3A (pg 243), in the second column, it gives the time that a 30mA RCD will trip in, at 60mA (2 x I delta N), as 150mS (0.15 mS)

As we require a disconnection time of 0.07 for our example, this is to slow.

So we go to the next column along - 150mA (5 x I delta N), which gives a trip time of 40 mS (as we know).

As this is within our disconnection time (70mS), then this is the figure we must use.

Yeah sorry about the big red writing. I made it a bit bigger and red so you would see it. Didn't mean to shout:Blushing

I get what you're saying now. It's because I was specifically looking for something that said 0.07 seconds.

Never really had reason to look at that table before but now you've explained it I understand it.

Thanks

 

[roys]

Thanks all for your help.

Just sat the test and passed.

Cheers Steve

 

[JUD]

Congratulations Steve!!!