Contactum Double Pole RCBO

[bernardgreen]

It depends how the test circuit induces the unbalance to trip the RCD section.

Most test buttons connect a resistor to the Live Out to create an un-balance between Live and Neutral currents in the sensor.

If the test connects the resistor between Live on one side of the sensor and Neutral on the other side of the sensor ( most often Live Out to Neutral In ) then using the OUTs as inputs and the INs as outputs will not stop the test working.

If the resistor is between Live Out and the RCBO's earth leade then using the device with INs and OUTs exchanged will not trip the RCD section as the test surrent is not passing through the sensor. And as long as the button is pressed the resistor will be between Live and Earth and carrying the test current of 30mA 230 v times 30mA is approx 7 watts, The resistor is not capable of carrying that power for more than a couple of seconds before it burns out. Normally the trip will operate long before the resistor gets hot enough to burn,

 

[Spark123]

Looking at the pic on the front of the RCBO when the device trips it also opens the connection to the resistor thus taking it out of the circuit too and limiting the energy dissipated in it, however should it fail to operate the resistor will burn up.
I don't like the idea of using L-E for the test circuit as a fault in the circuit i.e. an open circuit CPC will result in mains potential being seen on any connected metalwork.

 

[Taylortwocities]

Exactly my experience - TLC encouraged me to buy a Contactum unit which failed under test with smoke appearing from the unit although the switch itself seems to work OK. After taking advice from two experts & TLC I was satisfied it was a faulty unit and TLC replaced it foc. Same experience with second one and there is not enough free cable to put the supply at the top of the unit and load at bottom. Pity Contactum don't provide instructions or mark up their units to show that the supply must go in the top or must all RCBOs this way round? javascript:emoticon('')

I am glad its not just me then I expect TLC is trying to shift their stock as Contactum has now gone bottoms up. As a follow up, I got a replacement 40A RCBO from TLC, swopped over the feed and load (feed in the top) and ran all the tests, no problem.

I then connected up the (8.5KW) shower and the RCBO tripped if i used the high setting. I had to go buy a Wylex enclosure + RCD + 40A MCB from my local wholesaler. that and all works perfectly.
That cost me extra ££££ plus half a day extra time plus looking a right charlie in front of the customer

NO WONDER CONTACTUM HAS GONE BUST

 

[bernardgreen]

I don't like the idea of using L-E for the test circuit as a fault in the circuit i.e. an open circuit CPC will result in mains potential being seen on any connected metalwork.

I was told that the theory of resistor Live to Earth was that it also tested the earth conductivity was adequate to trip the RCD section. But as you say with a dissed earth during the test connected metalwork will be at mains albiet via the resistor.

 

[Spark123]

I haven't come across any devices which use an earth return for the test circuit as of yet. I think you might find it on some electronic RCDs - think someone was having fun with MK masterseal ones not so long back but hopefully these will not set if the earth isn't connected.

 

[bernardgreen]

What about RCBO (?) where there is the cream coloured earth lead ?

 

[Spark123]

I believe they are for voltage monitoring or for ensuring the device will still trip if the voltage between L&E drops below 50v, not to do with the test button.

 

[bernardgreen]

It would be better if the earth wire enabled the device to trip if the Neutral went more than 50 volts above true earth potential. ( true ground earth and not an earth derived from the incoming neutral )

 

[kai]

I noticed that Contactum kit can be poor at times, both in build quality and instructions, that's what probably contributed to their downfall.

Maybe you should have bought a Chint unit in the first place, and saved all this faffing around and time wasting on this shower installation.

 

[CharlesWest]

TLC are still selling these RCBO's. I have just tried to fit a new one to replace an identical one which showed evidence of overheating on the neutral side of the casing. I plumbed it in and it worked happily till I pressed the 'T' button. I heard buzzing and before I could isolate, smoke had started coming out. I'd connected the supply to the bottom terminals and the load to the top. I can see how they might have intended to represent 'in' and 'out' with '1' and '2', but this is a little obscure IMO. I have never come across this kind of terminology before, and if the device is so dependent on following this direction, it should have been made clearer.
I'll make damn sure I get my £21 back, but I have wasted a journey across Birmingham, and had to do my best to assure the customer that I am not a charlatan.
I'm going back tomorrow to fit a single-pole Hager breaker.
Wish me luck!

 

[ragenfury]

They still appear to be trading

http://www.contactum.co.uk/contact

these are the data sheets for all of their products the RCBO's included

http://www.contactum.co.uk/data-sheets

just installed 8 of them they all seem to work as described....

hope it helps

 

[Taylortwocities]

Yes, we know

They rose from the ashes - Phoenix-like - some time ago.

Thanks for the link to the docs but (if you look) the RCBO sheet only relates to the single pole RCBO, not the DP one that has caused problems.

Tell me, in your eight installs, was the L&N feed at the top, or the bottom of the RCBO?

 

[ragenfury]

My appologies, like my maths teacher said, read the damn question.

You're quite right I was installing single RCBO's with a bus bar feed at the bottom, circuit feed and neutral return at the top, built in tails going to the appropriate earth and neutral bar

"must try harder..."

 

[Taylortwocities]