RCBO Spec.

[lpdsn]

Does anyone know at what current a 16Amp RCBO should trip? Any links to a spec I can check?

Obviously, I wouldn't expect it to trip at exactly 16A, but I ramped the old one up to 19A and it didn't trip. As it was 25 years old I had half a mind already to replace it so I bought a new one. Did the same test and that didn't trip at 19A either.

 

[VicS]

Does anyone know at what current a 16Amp RCBO should trip? Any links to a spec I can check?

Obviously, I wouldn't expect it to trip at exactly 16A, but I ramped the old one up to 19A and it didn't trip. As it was 25 years old I had half a mind already to replace it so I bought a new one. Did the same test and that didn't trip at 19A either.

I assume they conform to the same standards as mcbs in which case the instantaneous tripping current will depend on the type . Type B trip at 3-5x the rated current, type C at 5-10x and type D at 10-20x

I am sure a bit of Googling with find the respective (B, C or D) curves

They will pass the rated current indefinitely without tripping

 

[Daydream believer]

Residual circuit breaker ? so is it the current overload that trips it or is it something else , ie earth leakage that sets it off?

 

[sailor211]

Residual circuit breaker ? so is it the current overload that trips it or is it something else , ie earth leakage that sets it off?

A device that is designed to do both, RCD and overload

 

[GEB]

The device has two functions. It has a circuit breaker function that protects against over currents due to either an overload or a fault. The overloads are generally detected by a bi-metal strip trigger. Fault current protection is generally triggered by a magnetic release device. The unit also has an earth leakage current detection function using a separate sensor.

As stated above, the circuit breaker functions are designed to work within standard ranges described by a number of different curves. The actual curves used depends on application but types 'B' and 'C' are commonly used. Without getting too involved, to meet the requirements for overload protection regardless of the curves selected, a device should operate at no more than 1.45 times the rated current within a specified time period (e.g 1 or 2 hours would be typical).

The earth leakage detection function also comes in various types depending on application. The types usually found in shore supply pillars or on boats usually trip if the earth leakage current is >= 30 mA within 300 ms, and within 40 ms if the earth leakage current >= 150 mA. Note that to achieve tripping at 30 mA generally requires that the device actually operates at a lower current (say, 23 mA). The device should not trigger it the earth leakage current is <= 15 mA.

 

[lpdsn]

As stated above, the circuit breaker functions are designed to work within standard ranges described by a number of different curves. The actual curves used depends on application but types 'B' and 'C' are commonly used. Without getting too involved, to meet the requirements for overload protection regardless of the curves selected, a device should operate at no more than 1.45 times the rated current within a specified time period (e.g 1 or 2 hours would be typical).

Thanks for the info everyone. I hadn't realised the trip could potentially be so slow for the current overload.

 

[VicS]

Thanks for the info everyone. I hadn't realised the trip could potentially be so slow for the current overload.

Another point in passing ITYWF that the majority of RCBOs intended for use in consumer units are only single pole devices. They do need a neutral connection in order to operate but they only trip the live supply to the connected circuits.

You will probably need double pole devices for your boat use .... they do exist but not so common as the single pole devices. Assuming you are talking about boat use.

 

[lpdsn]

Another point in passing ITYWF that the majority of RCBOs intended for use in consumer units are only single pole devices. They do need a neutral connection in order to operate but they only trip the live supply to the connected circuits.

You will probably need double pole devices for your boat use .... they do exist but not so common as the single pole devices. Assuming you are talking about boat use.

It's double pole. All the suppliers web sites I checked had double pole readily available.

Very necessary of course. Although I've not yet found a marina in UK/Irl that actually has the L & N reversed in any socket I've used.

 

[Daydream believer]

It's double pole. All the suppliers web sites I checked had double pole readily available.

Very necessary of course. Although I've not yet found a marina in UK/Irl that actually has the L & N reversed in any socket I've used.

I have found a lot in France & Belgium