flex in a FCU should be ferrules. go stand in the naughty corner.
I always make sure the terminal screw closes down on 2 surfaces, spreading the force. Either bending over a single solid core, or 2 unbent.
Fill up the terminal hole as much as possible.
Fill up the terminal hole as much as possible.
Aren't the terminal holes designed for one core then? It would be interesting to get an electrical accessory manufacturers input into this. It's more than reasonable to expect most common accessories to have either just one core in each connection or multiple cores in each one. Surly they should be designed to be equally secure with either option.
flex in a FCU should be ferrules. go stand in the naughty corner.
I stand before you and beg for forgiveness.
You are correct. I will improve.
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garyt
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Yes i think thats a good guide that i have always followed, but with the use now of the torque screw drivers i wonder if that will change.
Unless the terminals are designed to accept fine-stranded conductors. The old MK FCUs with wrap-around screws with captive washers, for example, were specifically designed for flex and could not be used with ferrules.
In general I double solid and class 2 stranded conductors in pillar terminals that do not have a conductor protection tongue. The screw tip bites into the conductor ensuring a gas-tight contact even when the clamping force is spread over the greater number of contact points of the doubled conductor, and especially with solid conductors the elasticity is improved to resist thermal cycling. Without doubling, the screw tip sometimes deforms and weakens the conductor too much, or the force is badly off-centre if a solid conductor is trapped to one side of it, causing it to slacken after a small amount of cold flow.
If there is a protection spring I tend to leave conductors single unless the screw is likely to bottom out due to a mismatch in size. These terminals do not chew into the conductor so badly and the pressure is more even over the surface. Rising clamp terminals do not normally need doubling either, unless they are of poor design or construction with a tendency for the clamp to tilt over, in which case I would double and position the conductor to apply the force symmetrically either side of the screw.
Making a good connection is a craft in itself that used to be taught in detail. Some of it is common sense, but there are all sorts of specifics that can help achieve a good result with any combination of cable and terminal. Knowledge of the properties of different metals, thermal cycling effects, chemistry of corrosion processes etc. can make a difference when the conditions are more demanding.
There were occasions during my Apprentice days in the 1950s early 60s when I was taught to bind larger conductors with a core of the said conductor when connecting say as an example a 7/064 into a terminal designed to take a larger conductor, just thought you would like to know that piece of
A good shout Pete, many are the times that I've whipped a conductor to make it fit. It's like making your own custom ferrule on the spot. The disadvantage relative to doubling or at least folding back a proportion of the strands is that all the current must flow through double the number of contact surfaces, from core to whipping wire and then to the terminal, but the same applies to a ferrule and isn't a problem if the correct torque is used.
MEM Exels were regular offenders for having terminals that wouldn't clamp down to the minimum size of cable that you might want to use. kWh meters and small tails were another situation.
I have been wrapping tails for years it prevents the conductors shifting. This is a 35mm bond I recently did, wrapped and you can see there is no shift and that is as tight as it goes.
Not really Sparkies then?
[automerge]1580842780[/automerge]
Did you tin the conductor prior to connecting?
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No, no tinning.
That's a nice job, I would have used a ring crimp if possible.
mainly because I don't have the patience to do all the fancy work as shown above!!
True. I must admit I was referring to not tinning when the wire was directly under a terminal screw, which should not be done. This is slightly different although the principle I think is the same.
nothing personal.
What was/is there to be pulled up on Mate, the people that ,make the rules are all seeing Engineers, aren't they???? or supposed to be. Gods to be obeyed no less.
Have you not had any experience, of soldering??? tinning is covering the copper with a thin layer of solder, thus sweating the cores together to put it simply, google soldering or tinnimg conductors may show you more than a difficult written instruction.
If he has a trainee banner then he may not be as experienced as older more seasoned electricians on this forum on different methods of terminations so I don’t understand the double question marks as if he should automatically know this method.
Why not educate rather than scoff?
Basic soldering should be a skill most Electricians, Trainees or Apprentices should posses in fact most DIYers have soldering skills, plumber do!!
I can count on one hand the amount of times I’ve soldered, it’s not that common Pete depending on your scope of work
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