Max Disconnection times

[Jim2287]

On tests sheets when you fill in maximum disconnection times allowed ...

5 Secs for lights etc non-portable fixed equipment

0.4 secs sockets supplying handheld equipment

0.2 (200ms) - for 30mA RCD protected circuits, sockets that could easily supply outdoor portable equipment

Is that correct ?


can anyone explain how you decide when an RCD is intended as supplementary protection against indirect contact ? .... surely any RCD is supplemetary protection ? only 30mA count as supplemtary protection ?

 

[Adam_151]

On tests sheets when you fill in maximum disconnection times allowed ...

Which forms are you looking at? Not max Zs ?

5 Secs for lights etc non-portable fixed equipment

0.4 secs sockets supplying handheld equipment

0.2 (200ms) - for 30mA RCD protected circuits, sockets that could easily supply outdoor portable equipment

Is that correct ?

Most stuff 0.4, lengthened discon. time of 5s applies to fixed equip but not anything outside equipotential zone, (but you ought to try and design to 0.4 in a house.) Ignore RCD times for the purposes of this

can anyone explain how you decide when an RCD is intended as supplementary protection against indirect contact ? .... surely any RCD is supplemetary protection ? only 30mA count as supplemtary protection ?

Its in the regs, can't remember the number but an rcd to provide supplimenary protection agaisnt direct contact much have an opperating current no greater than 30ma. Think of it this way, the 10ma is the extra safe, the 30ma the regualar condom, and the 100ma the handkerchief

 

[Jim2287]

Which forms are you looking at? Not max Zs ?

NICEIC forms have Max Disconnect Time on, aswell as max Zs for disconnection in that time .... im just trying to get the max times sorted


so basically its either 5 secs or 0.4 secs in houses, whether its protected by RCD or not

ive been writing 0.04 for a while, because i had it in my head 40ms was what you should write, after seeing 0.4 somewhere and thinking 'they' we confused

 

[Adam_151]

0.4s or 5s is the max disconnect time, the rcd is one of the ways of acheiving this (although unless TT its unlikly to be the primary means of doing so), so you'd no more write 40ms, than you would the 100ms for an mcb (or the much faster time gleaned from the makers datasheets)

 

[Jim2287]

ok, thanks for the help

 

[Adam_151]

To further the distinction in your mind, the boxes you are filling in are to do eith EEBADS, which is a method of protection against 'indirect contact' , so forget all about rcds for sup. protection agaisnt direct contact as far as those boxes are concerned

 

[Taylortwocities]

Further, in the schedule of items inspected sheet:

b) Protection Against Direct Contact

Item 8 Presence of RCD for Supplementary Protection


412-06, 471-16-01 (Page 159)
this means socket outlets rated at 32A or less which may reasonably be expected to supply portable equipment for use outdoors must be protected by an RCD rated at 30mA or less.(The person is now standing on true earth). This is the x5 test. Maximum tripping time of RCD is 40ms

That is the usual one that you tick unless you have a TT or similar (see below) so if you look down there's another RCD entry under

c) Protection Against Indirect Contact (Including EEBAD)

Under item 15 Presence of Residual Current Devices

531-02 (Page 166) An RCD is required in any circuit where the earth fault loop independence is too high for protection against indirect contact by other means. E.g. ELI measured exceeds max value in table 41B2 for an MCB(or 80% in NICEIC tables)

This is x1 Test for 30mA RCDS in a TT System. ZS x I^N < 50V given in regulation 413-02-16. This formula is modified to < 25V in special installations and locations(eg construction sites, agricultural premises).

Hope this helps.

 

[DESL]

NICEIC forms have Max Disconnect Time on, aswell as max Zs for disconnection in that time .... im just trying to get the max times sorted

I'm glad I use the IET/IEE forms

 

[securespark]

So do ours...