RCCD's and RCBO's

[La Poste]

This might sound like an obvious question but do rccd's have overcurrent protection?
When you buy a 17th edition board that has two double pole RCCD's one at 63A and one at 80A are these RCCD's effective for overcurrent as well as earth fault leakage?
I have been looking at double pole RCBO's that act as MCB's and RCD's combined and can be chosen in many different sizes from 6A upwards.
The RCCD's in a 17th edition board are designed to be used with MCB's so that one RCCD will supply an array on MCB's and the MCB's will act as overcurrent protection.
But why is the RCCD rated at 63A? Does this mean that it will also act as an overcurrent device if the current should exceed 63A.
Can these RCCD's be used both as overcurrent protection devices and as RCD's?
Cheers.

 

[Guest123]

No.....a standard RCD offers no overcurrent protection at all, only earth fault.

The 63A rating for example, is the maximum current that the RCD can be exposed to before it starts to overheat and generally get a bit annoyed. RCBO's have the benefit or providing both overcurrent and additional earth fault protection

 

[Hawk81]

When you buy a 17th board it has 2 RCDs not 2 RCCDs in it. The 80/63amp rating is just the safe working load not an overcurrent rating.

 

[La Poste]

OK thanks.
So RCD's have no over current protection.
So will an RCCD offer overcurrent protection the same as an RCBO?
I've read it does but not as effectively as a double pole RCBO although TBH I don't really know the difference between a RCCD and an RCBO if they both offer over current protection.
Also the 100A isolator switch on the board, does that have over current protection itself?
One more thing, can anyone recommend a brand for dual pole RCBO's?
I've been looking at these:
http://www.techna.biz/en/electrical/rtec.htm
They are about £30 each.

 

[Hawk81]

Again the 100amp main switch does not offer overcurrent. 100amps is what current the switch can safely work at. Yes an RCCD does offer overcurrent protection.

 

[La Poste]

Thanks mate.
So the only protection before the MCB's on a split load dual RCD board with a 100A isolator is the 100A main fuse at the point of entry of the supply. The suppliers fuse.
The RCD's offer no over current protection, the 100A DP isolator offers no over current protection.
The tails should be 25mm so why is it when you look inside a split load board the cables that supply the RCD's from the main DP isolator switch are less than 25mm, they look more like 16mm to me. You know the cables that join the RCD's together and join them to the isolator switch.

 

[Sintra]

The cables used inside the cu by the manufacturer have flexible strands so have a greater current carrying capacity than standard cable.

 

[nickblake]

The cables used inside the cu by the manufacturer have flexible strands so have a greater current carrying capacity than standard cable.

correct me if im wrong the flexible cables in at CDU are tri rated

 

[La Poste]

Is there a specific size for these cables inside a CU.
MK do a pack of cables for stacking boards.
If you want to create a second board below the first board they sell a pack of this very flexible cable.
They look like 16mm to me.

 

[jpmiff]

Hi
16mm2 trirated cable is rated at 100amps

 

[sjm]

Yes an RCCD does offer overcurrent protection.[/QUOTE]

Sorry but for overcurrent protection you need an RCBO as the O stands for overcurrent operation. RCCB is residual current circuit breaker which does not have overcurrent protection. RCCD is residual current circuit device still no O for overcurrent though.

 

[La Poste]

I fitted one of these.
Techna Circuit Protection : Residual Current Breakers with Overload
Trip times are 8ms on 30ma and 6ms on 150ma.
Quite impressive I thought.