E Electron1 Member Joined Oct 11, 2011 Messages 33 Reaction score 0 Oct 15, 2011 #1 That if a cable had a resistance of 76,666ohms it would trip a 30ma RCD 230 / 0.003 = 76,666 ????
Andy™ ©Resident Geordie™ Supporting Member Joined Jan 1, 2009 Messages 30,709 Reaction score 1,417 Location S. Tyneside Oct 15, 2011 #2 30mA is 0.03A and yes, IR of 7666 ohms would trip a 30mA RCD. or a L-E loop of 7666. however, to calc max Zs including touch voltage, calculation uses 50v, not 230v Last edited by a moderator: Oct 15, 2011
30mA is 0.03A and yes, IR of 7666 ohms would trip a 30mA RCD. or a L-E loop of 7666. however, to calc max Zs including touch voltage, calculation uses 50v, not 230v
E Electron1 Member Joined Oct 11, 2011 Messages 33 Reaction score 0 Oct 15, 2011 #3 Can u please explain touch voltage please? I thought Ze plus R1+R2 = Zs??
Andy™ ©Resident Geordie™ Supporting Member Joined Jan 1, 2009 Messages 30,709 Reaction score 1,417 Location S. Tyneside Oct 15, 2011 #4 max touch voltage during fault is 50v. Ze + R1R2 is Zs but to calculate Zs for an RCD with touch voltage of 50, you use 50 / RCD rating
max touch voltage during fault is 50v. Ze + R1R2 is Zs but to calculate Zs for an RCD with touch voltage of 50, you use 50 / RCD rating
E Electron1 Member Joined Oct 11, 2011 Messages 33 Reaction score 0 Oct 15, 2011 #5 O you mean in order to trip not a reading ?
kme Fridge Keyholder™ Supporting Member Joined Mar 7, 2008 Messages 9,984 Reaction score 0 Location In the office again. Oct 15, 2011 #6 No; he means in order to limit the voltage on exposed metalwork rising above the touch voltage limit, which is generally 50V, but can be 25V under certain conditions.
No; he means in order to limit the voltage on exposed metalwork rising above the touch voltage limit, which is generally 50V, but can be 25V under certain conditions.
steptoe of course Im wrong, ask my wife™ Supporting Member Joined Feb 13, 2008 Messages 24,402 Reaction score 168 Location Gtr Manchester Oct 15, 2011 #7 do they still teach the 50v rule anymore?
Zeespark Gold Member Supporting Member Joined Apr 24, 2008 Messages 3,940 Reaction score 11 Location Viva La Chesterfield, United Kingdom Oct 15, 2011 #8 Yes but it skimmed over like the TT system is, nothing of great depth. AndyGuinness
NozSpark Seaman stains™ Supporting Member Joined May 28, 2008 Messages 12,328 Reaction score 135 Location North Wales Riviera Oct 15, 2011 #9 do they still teach the 50v rule anymore? Click to expand... Doesn't look like it
kme Fridge Keyholder™ Supporting Member Joined Mar 7, 2008 Messages 9,984 Reaction score 0 Location In the office again. Oct 16, 2011 #10 do they still teach the 50v rule anymore? Click to expand... perhaps ^ would be a better question, mate??
do they still teach the 50v rule anymore? Click to expand... perhaps ^ would be a better question, mate??
S SteveT Well-known member Joined Oct 18, 2010 Messages 406 Reaction score 0 Oct 16, 2011 #11 Sip over touch voltage - it is a basic requirement to know this!!!!!!!!!