100ma RCD

[KNIPEX]

If a building has a 100ma RCD unit as a main switch would you insist on a 30ma one also to protect socket outlets on a PIR

main switch as an rcd doesnt comply anyway. im thinking code 3

Also a spur taken of a spur ive coded as 1 as its a fire risk imo, would you agree??

no main water bond also a code 1??

you do you think im being harsh with my codes?

how much do you guys test on a pir i normally do 50% of the board.

 

[davelerave]

sockets will need 30mA

afaik rcd is ok for isolation

spurs in series is bad practice anyway

 

[Deleted member 9648]

If a building has a 100ma RCD unit as a main switch would you insist on a 30ma one also to protect socket outlets on a PIR....If it is a TT system or sockets are likely to supply equipment outdoors I would code lack of 30ma rcd protection to sockets as a 2. For other sockets intended for general use on a TN system I would code 4

main switch as an rcd doesnt comply anyway. im thinking code 3 Not sure why you would code 3(requires further investigation)....I would code 4 (doesnt comply with regs)

Also a spur taken of a spur ive coded as 1 as its a fire risk imo, would you agree??Depends on the likely use,I would only code 1 if there was clear evidence of overloading or likely overloading,otherwise 2 which would still mean an overall unsatisfactory.

no main water bond also a code 1??Code 2...still unsatisfactory

you do you think im being harsh with my codes?

how much do you guys test on a pir i normally do 50% of the board.

Test all circuits,visually inspect a percentage of the installation,the percentage increasing if problems are apparent

 

[vardymr2]

main switch as an rcd doesnt comply anyway. im thinking code 3

Code 4

 

[Des 56]

main switch as an rcd doesnt comply anyway. im thinking code 3

Code 4

100 m/amp s type as a main switch is commonplace and was used extensively under the 16th ed for domestics
30 m/amp under the 15th ed as main switch
Code 4 for me

Be as harsh as you deem necessary
As long as you can justify a coding, if it is challenged

 

[Risteard]

Why would a 100mA S-type RCD as a main switch attract any code? Which Regulation does it not comply with?

 

[Sintra]

An RCD should not be used as a main switch. 314.2

 

[Benny_Boy]

An RCD should not be used as a main switch. 314.2

I thought a 100mA RCD as main switch/isolator was the way forward with TTs

 

[electricAl]

I thought a 100mA RCD as main switch/isolator was the way forward with TTs

Providing a 100mA rcd offers discrimination with downstream 30mA devices ( e.g its time-delayed) its use as an incomer is perfectly permissable where not all final ccts require Additional Protection.

 

[Deleted member 9648]

P 24 of the OSG shows a 100ma T/D RCD used as a main switch on a TT system,on a split load DB with only some final circuits 30ma protected.....I cant see how this can comply with 314.2 because a fault on any of the circuits not on the 30ma side will trip the whole installation.

 

[nickblake]

100 ma RCD was installed as a suplimentary protection for TT systems until the mid 80's when a amendment to the 15th edition regs came in , RCD main switches were also use in 16th edition but was changed in the later stages , now with current regs the main RCD protection is is no longer required because with a new CDU all circuits areRCD protected , the only installation which a main switch RCD is used is caravan supplies which has to be a TT supply ,with the installation of TNS and TNCS there are very few TT systems now in use ,having said that you do come across the from time to time

 

[Deleted member 9648]

I did a CU change on a TT yesterday and used a crabtree dual RCD insulated DB wth a standard main switch....there were 2 ways not on the RCD's and 1 was used with an RCBO.
I can only see that a100ma RCD main switch could comply if it was up front on a dual RCD board with all final circuits split over the dual 30ma's....in which case there would be no point....a standard main switch would do,like I used.

 

[devon1]

I am doing 12 monthly tests in london on RCDs

Test Procedures.

RCD TEST - PERSONAL PROTECTION SOCKET OUTLETS (16A,32A,63A)

Function Test: RCD should operate when 'test button' is depressed.

No Trip Test : RCD should not operate when half rated trip current is applied, ie if RCD does trip then nuisance tripping may occur.

Trip Test : rated tripping should cause RCD to trip within 200mS

Fast Trip : When tripping current of 150mA is applied the RCD should trip within 40mS

Earth Monitor : Funtion test : Disconnect of the pilot earth should cause the RCD to open. ( earth Monitor set to normal).


RCD TEST - EQUIPMENT PROTECTION OUTLETS (100A,200A,400A)

Rated tripping current : trip current should be selected & tested at 100mA (0mS), 300mA (0mS) & a selected mA plus mS time delay setting.

Funtion Test : as above

No Trip test : as above

Trip Test : as above

Trip with time delay : Rated tripping current with time delay should cause the RCD to operate within the range of 50% of rated time delay + 200mS & 100% of the rated time delay + 200mS.
ie, For 500mS time delay & a rated tripping current of 500mA the RCD should operate in the range of 350 to 750mS (250+100 to 500+200).

No Fast trip test. (X5).

Earth Monitor : as above

On completion of all tests if no load is connected, tripping current to be at lowest setting & time delay (if applicable) to be 0mS.

 

[davelerave]

it may be better to test with fault current imo - before pressing the test button

what do you think?

 

[devon1]

Yes i can see your point to do a trip test first. This trip test would prove if the RCD would work under fault conditions.

The RCDs sometimes fail without manual or Test button operation and need switching to loosen it up.

I have found that the RCDs are stiff and i need to be remove the cover and spray lubrication inside on to the trip coil mechanism to loosen it up . Then the RCD works correctly, not ideal i know.

 

[davelerave]

what spray are you using- i'm looking for something similar

 

[Risteard]

Still don't agree that 100mA/300mA/500mA etc. time-delayed RCD can't be used as a main switch.

Minimising inconvenience in the event of a fault doesn't require there to be no protection in the event of a fault.

 

[devon1]

The brand is 3-IN-ONE professional, high performance lubricant.

Drives out moisture
dramatically reduces frition and wear

 

[Deleted member 9648]

P 24 of the OSG shows a 100ma T/D RCD used as a main switch on a TT system,on a split load DB with only some final circuits 30ma protected.....I cant see how this can comply with 314.2 because a fault on any of the circuits not on the 30ma side will trip the whole installation.

A T/D RCD clearly can be used as a main switch as per the OSG I quoted above.
However a fault on the main switch side would trip the entire installation including the 30ma protected circuits in the arangement shown in the OSG.
This is somewhat contradictory to 314.2

 

[cornburn]

it may be better to test with fault current imo - before pressing the test button

what do you think?

On my NIC inspection I had a note on my assessment sheet for pressing the test button before testing with the meter. Apparantly it could damage it and it should only be tested last after the other tests have successfully been completed.