Name this device

[Octopus]

Honestly Murdoch don’t. Remove the earth connections and it becomes an isolator when you cut the test PB off. Far better than any crap you’ll get now a days.

Reasonable idea but they don't have RCD protection currently...but I could leave it and add the RCD above!

 

[ackbarthestar]

I know of a working example of this set up. We played around with it until it worked.
VOELB at the front end with RCDs on the final circuits.
You need to make sure that there are no other properties in the near vicinity otherwise you're back to the old problem of nuisance tripping.

 

[electric will]

Why not leave the voelb as a isolator, with the earth removed, then have a dual rcd board but swap the main switch for a 100ma rcd (time delayed)

 

[electric will]

If its tt I mean.

 

[Knobhead]

If Murdoch is fitting a modern plastic CU with 30mA RCD’s is there a need for a front end E/L unit? Just use it as an isolator. Makes the job safer as there’s no playing about with live tails or dare I say interfering with the service head. (I’ll go and get the carbolic mouth wash now).
I’ve only done this once, I super glued the test button and painted it and the label black with the wife’s black nail polish. SHMBO wasn’t happy though.

 

[Engineer54]

If Murdoch is fitting a modern plastic CU with 30mA RCD’s is there a need for a front end E/L unit? Just use it as an isolator. Makes the job safer as there’s no playing about with live tails or dare I say interfering with the service head. (I’ll go and get the carbolic mouth wash now).
I’ve only done this once, I super glued the test button and painted it and the label black with the wife’s black nail polish. SHMBO wasn’t happy though.

If this is a TT installation with the typical Naff Ra values the UK seems to have adopted, then it's more than worthwhile having a front end 100mA S type RCD. I personally wouldn't like to totally rely on a single 30mA either side of the CU, they are still not the most reliable protective device out there!! lol!!

 

[chronyx]

This is all before my time - a voltage-based RCD of sorts?

Were 'proper' RCD's too complicated/expensive to manufacture back then? Or not even invented?

 

[Stroppy]

Just not invented, I believe.

 

[Des 56]

These were used as isolation switches by that world renowned bathroom company Dolphin

If you have ever opened up a original Dolphin shower,the sneaky lads at Dolphin design pinched these breakers to use as isolation switches for their showers

Would you believe they had a fancy looking piece of string linked to the elcb which was mounted side ways on and a glass front to hide the dirty deed

 

[Knobhead]

This is all before my time - a voltage-based RCD of sorts?

Were 'proper' RCD's too complicated/expensive to manufacture back then? Or not even invented?

In industry the core balance earth leakage relay has been around for donkey’s years. (Even before me!) They would be fitted to distribution CB’s.
How the voltage operated E/L unit came about I don’t know. But they were a bloody menace from day one! To get one to work correctly the gas and water services had to be isolated from the service pipe with a short length of polypropylene pipe. The only earth point in the installation would be via the voltage-sensing coil in the ELCB and then out to a spike.
It doesn’t take a lot imagination to find the problems.
Their redeeming feature was they were cheap(ish). My first house I fitted RCD’s to each of the Wylex boards. They cost damn near £150 35 years ago!

 

[Knobhead]

These were used as isolation switches by that world renowned bathroom company Dolphin

If you have ever opened up a original Dolphin shower,the sneaky lads at Dolphin design pinched these breakers to use as isolation switches for their showers

Would you believe they had a fancy looking piece of string linked to the elcb which was mounted side ways on and a glass front to hide the dirty deed

If you come across one again Des, have a closer look. The same chassis was used for MCCB’s. They all have 3 blind 2BA mountings holes on the front for panel use.

As for Dolphin I'll keep quiet. Bunch of &&& ^%$&* &$^*&(^% *&^

 

[JonNewbie]

Hello, new here, but have a similar question... what is this? Is it a three phase version of the same thing (VOELCB). It says Crabtree, but not much else. And yes, the line conductors colours don't match!

 

[timhoward]

I believe that is a 3 phase earth leakage circuit breaker with overload protection. A kind of primitive RCBO with different leakage detection method, relying on a coil between real earth and installation earth.
Under the stickers there once would have been a plate that told you exactly what it is. See example of another one below.

I'm sure you already know that it needs taking out of service. And as the stickers read like a list of special locations with special requirements this one may need more than a little thought.




If you remove it, save it, as collectors might like it!

 

[pc1966]

It looks like it.

Also something to have checked professionally to see if you have adequate protection for the installation as a whole since VOELCB have a number of issues, one being they are generally old and may not be tested (have you test tripped it?) and the other being that any additional earth bonding can make them ineffective at detecting a fault.

The other worrying sign is the apparent shuffling of phases!

It might be that device is now largely redundant if the distribution boards have RCDs in them providing the required level of protection, but I certainly would suggest it is checked. Do you have photos of the board(s) the device is feeding?

 

[JonNewbie]

It looks like it.

Also something to have checked professionally to see if you have adequate protection for the installation as a whole since VOELCB have a number of issues, one being they are generally old and may not be tested (have you test tripped it?) and the other being that any additional earth bonding can make them ineffective at detecting a fault.

The other worrying sign is the apparent shuffling of phases!

It might be that device is now largely redundant if the distribution boards have RCDs in them providing the required level of protection, but I certainly would suggest it is checked. Do you have photos of the board(s) the device is feeding?

Thanks Tim & PC!!
The device feeds a 3P 63A switch fuse next door to it, then a long run of armoured cable to a modern 3P board, with RCBOs. Apparently the device is tripping once in a blue moon when there is a lot of load on. Sounds like from what timhoward says, it may be overload rather than leakage that trips it?. Sadly the plate is no longer there.

 

[pc1966]

The device feeds a 3P 63A switch fuse next door to it, then a long run of armoured cable to a modern 3P board, with RCBOs. Apparently the device is tripping once in a blue moon when there is a lot of load on. Sounds like from what timhoward says, it may be overload rather than leakage that trips it?. Sadly the plate is no longer there.

It sounds like it, though of course enough accumulated leakage might trip a RCD-like device (though on 3P a lot of the would cancel so really it would be imbalance on leakage).

If this is a TT set up then the sub-main would need some sort of RCD protection as a L-E fault there would probably not take out any supply OCPD. As there is a switched-fuse for overload (I guess?) all that would be needed is a delay RCD. Also it probably falls in to the special locations where <= 300mA RCD for fire is required.

If it were my business I would look at replacing it with a 100mA or 300mA delay RCD in a suitable enclosure.

 

[timhoward]

It could be overload tripping it. Or it could be a fault with a distribution cable. I'm afraid it really needs looking at.

These devices are often found where the earthing for an installation is a rod in the ground (known as TT), and the original job is turning things off safely if there's a fault. With this kind of earthing it's very important to have a device like this as not enough current will flow to operate the suppliers fuse under fault conditions.
Anything between the RCBO's and the origin are probably relying on this for fault protection, and even if it's working it really needs replacing with a modern RCD.

 

[timhoward]

This might be helpful to illustrate the point: (First 6 minutes will do.)

 

[JonNewbie]

It sounds like it, though of course enough accumulated leakage might trip a RCD-like device (though on 3P a lot of the would cancel so really it would be imbalance on leakage).


If it were my business I would look at replacing it with a 100mA or 300mA delay RCD in a suitable enclosure.

Thanks PC! Yes, it's TT. I was thinking 300mA type S. So much hanging off it, 100mA could nuisance trip, even with everything on 30mA RBCOs. I think they left this in as they did not want to mess with the meter tails...

 

[westward10]

STD stands for Short Time Delay.