'Neural connections inaccessible on Lewden RCBO's'

This is indeed a headline ... Fully intelligent RCBO's now available.

I guess you're there with a brain surgeon trying to get into the 'neural connections'?




Sorry ... had to post this, I was looking at the thread title trying to work out what was wrong, until I saw the missing 't'.

Yeh, but the important thing is that Alan B knew what he meant, and we did as well.

Z.

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Unknown said:

Hi graham, perhaps you were forgetting the over tightened connection that was allegedly the cause of the Clandon Park Fire?

No problem with my neural connections.

Unknown said:

Let’s not beat about the bush, there is no way to to test an existing termination for torque without loosening the termination then retightening it with a calibrated tool. 

And there are arguments I've heard, regarding the fact that even if you do tighten to the correct torque, there's no saying it will stay that way ad infinitum (loosening over time) ...

I wasn't picking at the question, just the fact that I found a minor typo amusing "neural" rather than "neutral" - leading to "intelligent circuit breaker".

Zoomup said:

Yeh, but the important thing is that Alan B knew what he meant, and we did as well.

Me too ... just found the "neural" thing funny, guess my neurons don't always fire in the same way as others

IQuote. "Investigators have concluded that the fire was accidental and the probable cause was a defect in an electrical distribution board located in a cupboard in the basement.

The report states that the distribution board ‘could be assumed was delivered from the manufacturer with this fault."

Most manufacturers have stickers on their switchgear that say CHECK TIGHTNESS OF FACTORY FITTED SCREWS AFTER INSTALLATION.  We would normally do this anyway, as the equipment may have been thrown about and rattled about during delivery to suppliers and then travelling to site.

Also, after removal, I NEVER re-terminate solid copper wires if the ends have been in any way crushed or damaged, by say a tight screw. The indented solid copper conductor is liable to break after being moved. I strip the insulation off and cut the damaged section of wire off. Also I am a great fan of doubling over the conductor to provide greater area for a screw or clamp to contact with. This also reduces the chance of the conductor becoming loose if the wire is moved in the future.

Z.

IQuote. "Investigators have concluded that the fire was accidental and the probable cause was a defect in an electrical distribution board located in a cupboard in the basement.

The report states that the distribution board ‘could be assumed was delivered from the manufacturer with this fault."

Most manufacturers have stickers on their switchgear that say CHECK TIGHTNESS OF FACTORY FITTED SCREWS AFTER INSTALLATION.  We would normally do this anyway, as the equipment may have been thrown about and rattled about during delivery to suppliers and then travelling to site.

Also, after removal, I NEVER re-terminate solid copper wires if the ends have been in any way crushed or damaged, by say a tight screw. The indented solid copper conductor is liable to break after being moved. I strip the insulation off and cut the damaged section of wire off. Also I am a great fan of doubling over the conductor to provide greater area for a screw or clamp to contact with. This also reduces the chance of the conductor becoming loose if the wire is moved in the future.

Z.

Zoomup said:

Also, after removal, I NEVER re-terminate solid copper wires if the ends have been in any way crushed or damaged, by say a tight screw. The indented solid copper conductor is liable to break after being moved. I strip the insulation off and cut the damaged section of wire off. Also I am a great fan of doubling over the conductor to provide greater area for a screw or clamp to contact with. This also reduces the chance of the conductor becoming loose if the wire is moved in the future.

I think that you are contradicting yourself here.

I agree with chopping off the last 1/4" or so if the conductor has been indented significantly, usually in the earth or neutral bar rather than the RCD/RCBO. That's why I like to leave circuit tails slightly long. Admittedly, however, doing this once a decade isn't going to cause much shortening.

Bending the ends over 180º weakens the conductor at the hairpin so there are pros and cons to this technique.

Actually Chris, I am a doubler too. I always at least double (sometimes I Quaddle) , I think one careful bend tight will not usually over-stress copper conductor and the benefit is better contact - In an ideal world we would aim to have almost the whole circumference on the round terminal hole in surface contact with the circumference of the conductor. We can`t actually achieve that but adding more conductor material in the hole goes part wat towards it I think. I don`t like twisting because it sometimes encourages untwisting but a light twist on 7 stranded conductors or a bit more on flexes perhaps helps to keep it tidy and sort of contained under the screw sometimes