Main switch in consumer unit

[Dambo]

If it was not a time delayed one then most likely yes.

What's the difference between time delayed and not time delayed?

 

[ianmacd]

It will wait a specified time before tripping to see if the fault clears (or is cleared by another protective device)

 

[Dambo]

It will wait a specified time before tripping to see if the fault clears (or is cleared by another protective device)

Am I right in saying though that 30mA RCDs protecting circuits won't be time delayed?

 

[Lurch]

Am I right in saying though that 30mA RCDs won't be time delayed?

Generally no, 30mA RCD's are not time delayed as they are usually there to protect the final circuit. It is the upstream RCD's that will be time delayed as they are there for general overall protection so are effectively a last resort.

 

[m4tty]

Generally no, 30mA RCD's are not time delayed as they are usually there to protect the final circuit. It is the upstream RCD's that will be time delayed as they are there for general overall protection so are effectively a last resort.

So there are 30mA time delay RCD's available ?

Ive never heard of one so just wondered if there was such a thing

Cheers

 

[Lurch]

So there are 30mA time delay RCD's available ?

Good question, never looked TBH. Task for later.

 

[a1]

I wouldn't have thought that Time Delay was available on 30mA RCD s. Due to them deing used for Electric Shock Prevention? :|

But who knows?

 

[M107]

I think protek still do a 30mA S (time delay) type

 

[Lurch]

I wouldn't have thought that Time Delay was available on 30mA RCD s. Due to them deing used for Electric Shock Prevention? :|

It would depend, there is no reason why you couldn;t use 30mA time delayed RCD's as long as all the measures for protection are met. It could be that the final circuit has to have a 10mA RCD for protection for whatever reason but the 30mA is used fro the wiring due to being <50mm, or something. Dunno, could be used though.

 

[Dambo]

Am I right in saying it's possible (although not probable) to use a 30mA RCD to protect the circuits and a time delayed 30mA RCD as the main switch?

 

[SteveH37]

My CU (consumer unit before we go down that road) only has one RCD and it is the isolator as well. I believe it was fitted in 1988. I have had no nuisance trips and it is tested regulary.Cheers Steve

Mine is the same from about the same era too, Hagar (YUCK!) but no problems to date.

 

[spinlondon]

Am I right in saying it's possible (although not probable) to use a 30mA RCD to protect the circuits and a time delayed 30mA RCD as the main switch?

Remember that you must allow for cumulative earth fault leakage.

Computers are known to have earth fault leakage, as are cookers, fridges and freezers.

 

[Dambo]

Remember that you must allow for cumulative earth fault leakage.Computers are known to have earth fault leakage, as are cookers, fridges and freezers.

One final question - With regards time delayed main switch RCDs, if a 30mA RCD protecting circuits trips, as the RCD would then be in the OFF position, am I right in saying that this fault current then WOULDN'T feed through to the main switch RCD?

 

[spinlondon]

One final question - With regards time delayed main switch RCDs, if a 30mA RCD protecting circuits trips, as the RCD would then be in the OFF position, am I right in saying that this fault current then WOULDN'T feed through to the main switch RCD?

Yes.

 

[batty]

Wow four pages to answer a simple question.

 

[Lurch]

Wow four pages to answer a simple question.

No, 2 posts to answer it, 3.5 pages to argue the point for no apparent reason.

 

[SPECIAL LOCATION]

You CANNOT have an RCD as a main switch or isolator in a domestic installation.

Oh dear! :_|

I really hope you are not seriously suggesting this is true?

I shall have to go and rip some pages out me books other wise....

Try Page 24 Onsite guide.

Figure 3.2

note the wording of the heading...

"Typical split load CU with Time Delayed RCD as Main Switch!

Suitable for TT and TN installations etc.. etc..."

and the arrow pointing to the main switch

(100ma time delayed RCD S-type double pole labeled as Main switch)

ALSO FOUND IN

Guidance Note 1. "Selection & erection"

Page 46

Figure 3.4

:_| :_|

looks like me new 17th edition books and guides are all wrong!!! :_| :_| :_| :_|

 

[niceguy]

Even in a TT system, you no longer need to have a 100mA s type RCD as a main switch.

And yes, it did take many pages to get a point across.

It just seemed that i didnt put my posts past "those that matter" to proof read.

 

[Lurch]

Even in a TT system, you no longer need to have a 100mA s type RCD as a main switch.And yes, it did take many pages to get a point across.

It just seemed that i didnt put my posts past "those that matter" to proof read.

That's not what you said though. And it wasn;t a matter of proof reading anything, it was a matter of your blanklet statement which was incorrect. You can say whatever you want, but you cannot say that what you said was correct, which you clearly have an issue with.

 

[niceguy]

You are correct and rightly or wrongly i assumed (yeah whatever) we were talking domestic with a 30mA.

Right....... now wheres me pills.