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were would you use a time delay rcd and what are the benefits of doing so is it just in tt installations
Discuss time delay rcds in the UK Electrical Forum area at ElectriciansForums.net
Well use a S Type delayed as the main switch, that's a saving on a main switch, and a 30 Ma RCD on those circuits that require it, which without knowing the job is all of them possibly, I don't want to come across as critical your not insisting on RCD protection on a CU change ? and don't forget also the enclosures type needs to be a class 2 or all insulated for TT's as I interpret the regs
ATB J
I think you misunderstood me. I was not quoting for a CU change. The work asked for was an outside socket off another, RCD protected, CU. I just noticed that the main CU supplying most of the house circuits didn't have any RCD protection and told the guy that wasn't clever. Not suprisingly the guy doesn't want a £100 job turning into a £500 job with CU change so wants the minimum that will give him some protection. That would be an up front 100mA RCD without touching the main CU.
were would you use a time delay rcd and what are the benefits of doing so is it just in tt installations
good point but it does then refer you to 411.1 >415.1.1agricultural and horticultural
705.442.7
Sorry dude got wrong end of stick, just note it on the minor works to cover your ---
ATB J
If you are installing a socket-outlet to be used for mobile equipment outdoors, then the socket-outlet will require 30mA RCD protection.
The problem you have with installing a time delayed up front RCD, is what delay you will use.
1s for distribution circuits, or 0.2s for final circuits?
Thanks Engineer 54 , i had never heard of the x3 recommendation .
That's because for RCDs it doesn't happen. As Eng 54 has said.
I rather think the x3 refers to discrimination of fuses, mcbs etc.
Lets say you have a 300mA RCD main switch(non time delayed) and sockets protected by a 30mA RCD.
Which RCD will trip first if there's a big earth fault on one of the sockets of more than 300mA? Its the RCD with the faster (time) trip characteristic or it may depend on where the AC sine wave is at. It could really be either, or - sometimes - both of them.
An S-type is the only way to ensure discrimination of RCDs.
Also there would be no need to use a 100mA rcd main switch if all circuits had 30mA Rcbo's would there?
But you are correct, for a domestic TT all RCBO there is no need for additional 100mA RCD incomer.Also there would be no need to use a 100mA rcd main switch if all circuits had 30mA Rcbo's would there?
But you are correct, for a domestic TT all RCBO there is no need for additional 100mA RCD incomer.
Just a normal DP main switch.
i thought you needed the 100ma as main switch if the cu was metal.that seems the norm on the ones ive seenBut you are correct, for a domestic TT all RCBO there is no need for additional 100mA RCD incomer.
Just a normal DP main switch.
i thought you needed the 100ma as main switch if the cu was metal.that seems the norm on the ones ive seen
i thought you needed the 100ma as main switch if the cu was metal.that seems the norm on the ones ive seen
I think your right there, but it would still have to be an S type, if you wanted to maintain discrimination!!
I may be wrong , but if using a metal cu it will need a insulated shield around the incoming part / section of the cu to give extra protection to the tails before the rcd .
This may not be applicable now days , but it seemed to be standard practise on nearly all of the older TT boards i have come across ?
I hope you do not mind me asking Engineer54 ,or anyone else to that matter .
Was this the case in the past or have i been misguided to believe so ?
Sorry Alarm man , got the wrong end of the stick with your post .
I took it that you meant the main switch was in the cu and not a stand alone !:49:
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