RCBO Burnt out on busbar

I don't JP, I am well used to using torque wrenches on the bikes and cars I often work on but I think with the electrical stuff if someone cannot tell how tight to make a connection they shouldn't be doing it anyway! I do think it would be better if they made the screws with torqs heads or perhaps allen type heads as this would give a more positive purchase than the phillips type screw heads especially when they get a bit worn.

 

Cheers Sen. Same I have never used a torque screwdriver on a DB etc and it is really down to commonsense to feel tightness. Must agree the Phillips screwheads are not ideal as the purchase is questionable..but in the end after graunching somewhat you can get it nice and tight..but as you say torq heads or allen would be great.

Do people tighten up, and then back off and retighten? On cylinder head bolts etc I use to take it up to 70ib/ft (as an example) and after a few minutes back off the bolts around half a turn, and then tighten back to said torque.

 

That is a good idea JP. Also if just checking an existing fixing it is best to slacken half a turn and then re-tourque.

 

Definitely Sen. I can see why a certain amount of DB's were subject to ignition - all mostly down to loose/non properly tightened mcb/ main switch etc etc screws. I wonder if the most common cause of db overheating was due to main switch screws being/becoming loose? You know the 16mm/25mm etc tails not being flattened first before putting in tunnel, and to compound the problem just first tightening carried out with no back off and re tighten.

 

Any links to a torque screwdriver JP

I have never used one

 

I've never used one for electrical work Tore - however Norbar are the leaders with respect to torque instruments (not cheap though) http://www.norbar.com/en-gb/ ..hope that helps m8.
There must be other manufacturers, but the only one for me would be Norbar.

 

http://www.norbar.com/en-gb/norbar-product-search/Search/Torque Screwdriver, adjustable, TTs6`0 N·m

Lots of them above - however how many people actually use a torque screwdriver within domestic/industrial electrics I would not know - its up to the individual tbqh to make the decision.

 

Take your pick. http://uk.rs-online.com/web/c/tools/screwdrivers-screw-extractors/torque-drivers/?sra=p Dont knowhow good or suitable any of them are.

Kind regards

 

Remember that the torque on MCBs is only about 2.5Nm it's very difficult to judge something that low. I would expect most peoples touch would be well over that.

 

Well, to be accurate about it even the neutral is a live.

 

They aren't cheap was never told about them!


Interesting and frightening post.

 

It is for now.
Next week it may not be.

 

Torque screwdrivers are intended to ensure a minimum tightness, not a maximum. I just tighten the screws as tight as I can, probably a lot more than 2.5Nm. And I don't use a torque screwdriver. Waste of money.

 

Agreed UP.

The only time I have used a torque driver was back in the 70's when they introduced copper clad cable (aluminium core with a copper coating for those who haven't heard of it).

It was a cow to work with and had to be twice the size of copper. Glad it was scrapped, and god help those that were left with it.

Kind regards

 

Agreed UP.

 

80A rcbo? - seems a monster. Sure its not an RCD?