RCDs and RCBOs..Whats the difference you may ask?(Off Topic)

harrisonline · 19 Mar 2009

Big_Spark said:
I read on the other Electrical forum an old discussion about RCD's and American GFI's. In this discussion it was stated that RCD's do not give Overload protection, however I would like to point out that this is wrong, RCD's DO give overload protection, only basic, but it is there.

For example, a 100A 30mA RCD will trip if the difference between the load on the Phase conductors (Live and neutral) exceeds 30mA or if a 30mA or higher current is detected on the CPC (Earth). Further, if the total load being drawn through the RCD exceeds it's maximum rating, then the RCD will trip and disconnect the circuit.

However, and this is where many people get confused by this, a standard RCD does this by electronic determination of the load current via the detection circuitry unlike the MCB's and RCBO's. The torus forming the heart of the RCD has a small detection circuit attached to it via an op amp. The magnetic field detected by this circuit is carefully measured and if it exceeds a certain thresh-hold, as determined by the maximum load rating, then it will disconnect the circuit

To clarify this, RCBO's combine the operation of the MCB and the RCD into one unit. The RCD part operates in exactly the same way as the standard RCD, however for overload protection the RCBO contains magnetic or thermal trips, in good quality units, such as MK, Merlin-Gerin and Hager, the RCBO contains BOTH thermal and magnetic trips, just as an MCB does.

It is these differences that dictate the use of such devices. RCBO's are used to protect individual circuits that need that extra level of safety, but overload protection is still a vitally important aspect, whereas RCD's are useful, in certain circumstances, for replacing Isolators in Consumer units, Distribution Boards etc where effective disconnection may be required in an emergency or for maintenance etc, but overload protection is not required.

I hope this clarifies the difference between these devices, a proper understanding of the devices will certainly help to determine their proper use.

You think we are peanuts or something?

Spark123 · 19 Mar 2009

He maybe does, but Big_Spark, FWLenginner, ETHunter or whatever he calls himself nowadays doesn't post here anymore, unless he has another username.

harrisonline · 19 Mar 2009

This post gave me an urge to read other early posts an this is the earliest I can find.

//www.diynot.com/forums/viewtopic.php?t=31

Is it really the first post or have earlier ones been deleted. Its classic anyway!

ban-all-sheds · 19 Mar 2009

harrisonline said:
This post gave me an urge to read other early posts an this is the earliest I can find.

ban-all-sheds · 19 Mar 2009

ellk9203636nib said:
What a lot of crap.

FWL's speciality....

ColJack · 19 Mar 2009

YAY!!!! he's back...

now be a good boy and behave BAS.. it's been hard work feilding it all myself today...

mdbalson · 19 Mar 2009

ColJack said:
YAY!!!! he's back...

now be a good boy and behave BAS.. it's been hard work feilding it all myself today...

You know what BAS is like, it's impossible for him to be good & behave, he loves to argue & wind up/ call the mods names.

17thman · 19 Mar 2009

"reports of my death have been greatly exaggerated"

you T**S P*T

harrisonline · 19 Mar 2009

Hes only been gone for a day for F*** Sake!

mdbalson · 19 Mar 2009

you will start BAS of again at this rate

Click-Sure · 20 Mar 2009

That first post took nearly 2 and a half years to get a reply!

Looks like the DIYnot.com Garden is about a popular as the Blue Peter garden.

hairyben · 20 Mar 2009

ColJack said:
again..... 2004 people..!!!

please check the date before replying to long dead posts..

Given the thread was resurrected and prominent, I thought my post was an important safety clarification for the unsure and unwitting and I'm surprised no-one's made the point before.

I'm sorry that it doesn't sparkle with you.

JACKC · 20 Mar 2009

BAS called me a name once, I didn't log on for 24 hours That'll learn him.
Silly old cart.....

Taylortwocities · 20 Mar 2009

Reminds me of that Monty Python sketch where the guy could not say the letter "C" and used a "B" instead.

Silly bunt

ericmark · 21 Mar 2009

JACKC said:
BAS called me a name once, I didn't log on for 24 hours That'll learn him.
Silly old cart.....

Thought the word was teach!

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RCDs and RCBOs..Whats the difference you may ask?(Off Topic)

harrisonline

harrisonline

harrisonline

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