I hate those euro style connectors, they seem to use them in small 3 phase motors and such. I have come across several that have burnt. The common terminal strips are far more reliable. jean-paul knows what he is talking about.
I have serviced industrial controls with hundreds of connections on terminal strips and failure is very rare.
BillWojo
I have serviced industrial controls with hundreds of connections on terminal strips and failure is very rare.
BillWojo
I have always used the barrier terminal strips (aka "American" style.)
If you need multiple connections to one terminal, you instead use a copper bus bar on the "out" side and connect as many as required.
The bar is thin enough that you can always add a bare wire or terminal as needed on top of it, and they snap to your required length.
If you need multiple connections to one terminal, you instead use a copper bus bar on the "out" side and connect as many as required.
The bar is thin enough that you can always add a bare wire or terminal as needed on top of it, and they snap to your required length.
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Another vote for barrier terminal blocks and fork terminals.
If you must use wires without crimp terminals, don't be tempted to solder the wire to prevent fraying. Solder gives way (flows?) under pressure, so the connection will gradually loosen, unless you regularly tighten the terminal screws (presumably they eventually hit solid copper and will stop loosening). There are crimp ferrules which are the proper thing to use for such terminal blocks, but they need an expensive crimp tool (last time I looked).
If you must use wires without crimp terminals, don't be tempted to solder the wire to prevent fraying. Solder gives way (flows?) under pressure, so the connection will gradually loosen, unless you regularly tighten the terminal screws (presumably they eventually hit solid copper and will stop loosening). There are crimp ferrules which are the proper thing to use for such terminal blocks, but they need an expensive crimp tool (last time I looked).
I was just discussing this with someone the other day and we also couldn't find what we are looking for. Does anyone have a source on the power terminal blocks like what are used on Linear Power HV series amps? 2.2HV, etc. I can't see to find a panel mount like them so maybe I'm using the wrong description as well? Thank you!
Handy is not the parameter that is key in electrical stuff seen from a safety or technical point of view. They are not well insulated as the contacts on many of them can be touched by hand. A loose wire will make contact with contacts in Euro blocks. That they can be used floating is not a plus in many cases but it saves a screw. In industrial environments where stuff vibrates you can wait on them to fail.
There are better solutions but Euro blocks are the cheapest of all. So they are used most, certainly in cheap stuff and in consumer stuff like household appliances and lamps. If one crimps "cable shoes" over the wires they will last but putting bare wire in them is asking for trouble. A recent issue is that contacts may be made of plated steel. Since they are so common no one checks brand or quality. For mains voltage purposes they are better suited than for low voltage/high current as contact points are small. The OP wants to use them at the secondary side of a transformer which is exactly the situation where you should avoid them.
Can be applied fast, are very cheap, available everywhere and everybody knows them. Winner.... A professional electrician tends to avoid them.
The barrier style terminal blocks also have the bonus that a not right tightened ring connector will not easily come off and cause a short. Although installed erroneously it will still make contact. The only way to find such a situation is using an IR heat camera.
BTW the American versus Euro naming is a bit strange. We use both with their technical names for ages and I have never heard of them being American or Euro. In the electrical world devices etc. often are known for the brand that was first to produce it like Wago: "give me a Wago with 3 contacts please". The "Euro block" better be named "world block" as you will find them everywhere where the sweet smell of cheap is.
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You must have very dainty little fingers Jean-Paul 20A 12 POSITION TERMINAL BLOCK | All Electronics Corp.
How does someone use a ring or fork lug to terminate a stranded construction wire into these molded terminal strips?
You don't.... you use the appropriate lug for the application.
In this case it's a flat blade, lip blade or pin type pre-insulated crimp lug OR the correct size copper ferrules [that don't necessarily need an expensive crimp tool due the their thin tubular construction.]
Likewise, I'd QA fail or defect notice a control panel where some idiot has used ferrules, blades or pin lugs to terminate CT secondary wiring connections. Even fork lugs are dubious in such applications. You know what happens if a CT goes open circuit while rated current is passing through primary?
Andrew correctly suggests the best use of these twin screw terminal strips, if possible, is to have two screws act on both conductors in the tunnel. If an Earth is connected in these, as you do find, that 2 screw method should be used.
These terminal strips, as lowly as they are, come in a variety of design. The very worst have a screw diameter much smaller than tunnel diameter, the better type have screw nearly same diameter as the tunnel.
The lowest quality have screws acting directly on the conductor. - cheap and nasty.
The better type have a metal plate between conductor and screw.
The best of them have a metal plate with serrations to prevent tension pull out of the conductor.
In the first post we see a transformer termination. If thats solid core wire [not flex stranded construction] it would be very unwise to use the cheap screw only type.
As far as my long industrial experience goes, I've only seen one manufacturer suggest a screw type terminal [DIN rail mounting] doesn't require a lug due to serrations on clamp plate. In any case, never seen an industrial specification state that lugs or ferrules are not required.
You don't.... you use the appropriate lug for the application.
In this case it's a flat blade, lip blade or pin type pre-insulated crimp lug OR the correct size copper ferrules [that don't necessarily need an expensive crimp tool due the their thin tubular construction.]
Likewise, I'd QA fail or defect notice a control panel where some idiot has used ferrules, blades or pin lugs to terminate CT secondary wiring connections. Even fork lugs are dubious in such applications. You know what happens if a CT goes open circuit while rated current is passing through primary?
Andrew correctly suggests the best use of these twin screw terminal strips, if possible, is to have two screws act on both conductors in the tunnel. If an Earth is connected in these, as you do find, that 2 screw method should be used.
These terminal strips, as lowly as they are, come in a variety of design. The very worst have a screw diameter much smaller than tunnel diameter, the better type have screw nearly same diameter as the tunnel.
The lowest quality have screws acting directly on the conductor. - cheap and nasty.
The better type have a metal plate between conductor and screw.
The best of them have a metal plate with serrations to prevent tension pull out of the conductor.
In the first post we see a transformer termination. If thats solid core wire [not flex stranded construction] it would be very unwise to use the cheap screw only type.
As far as my long industrial experience goes, I've only seen one manufacturer suggest a screw type terminal [DIN rail mounting] doesn't require a lug due to serrations on clamp plate. In any case, never seen an industrial specification state that lugs or ferrules are not required.
It is probably a good hint that all of the available power supplies for our use have the screw terminals. One issue I have had with their use is the inadequacy of the self made termination on the wire. I have had them come loose. But I did pick up a proper crimping tool and have made a few terminations I am pleased with and I will probably be using spades and ring terminals more often. The crimper in question is the Klein 1006. Its' jaws are wide and crimp the wire tightly. The crimpers on a typical wire stripper are totally inadequate.
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Unfortunately, these Klein 1006 crimpers are rather 'low end' and are only suitable for NON-insulated type lugs.
They have an indent function that would damage the plastic sleeve of a pre-insulated type lug, nor are they suitable for use on ferrule [bootlace] lugs.
They do not have a ratchet mechanism to ensure consistent and adequate crimping pressure is applied every time.
Professional, I have 3 types of crimper for the common lugs found in the electrical trade. They are not 'cheap', but cheaper than the outcome of a dodgy crimp or loss of reputation.
Likewise, decent wire strippers.
An example of high quality crimpers and wire strippers is seen here.
You can see the specific crimp jaw design for the 3 common lugs used in Industry.
And yes, even similar design crimpers from other manufacturers can be very 'low end'.
Incidentally, the crimper brand cited in link above, Weidmuller, are better known as a manufacturer of very high quality terminal blocks. You won't find 'low end' strip terminal blocks in their catalogue.
They have an indent function that would damage the plastic sleeve of a pre-insulated type lug, nor are they suitable for use on ferrule [bootlace] lugs.
They do not have a ratchet mechanism to ensure consistent and adequate crimping pressure is applied every time.
Professional, I have 3 types of crimper for the common lugs found in the electrical trade. They are not 'cheap', but cheaper than the outcome of a dodgy crimp or loss of reputation.
Likewise, decent wire strippers.
An example of high quality crimpers and wire strippers is seen here.
You can see the specific crimp jaw design for the 3 common lugs used in Industry.
And yes, even similar design crimpers from other manufacturers can be very 'low end'.
Incidentally, the crimper brand cited in link above, Weidmuller, are better known as a manufacturer of very high quality terminal blocks. You won't find 'low end' strip terminal blocks in their catalogue.
A ratcheting crimper would be great to have, but I'm afraid I'm not up to spending $100+ for one. The Klein 1005/1006 series crimpers are perfectly adequate for occasional use and are actually in many a technician toolbox here, I bought mine at an HVAC supply house and was told "this is the one every one gets" when I asked for one.
The Klein 1006 is described as for non-insulated connector termination. I was fixing my AC yesterday and was in this commercial supply house and this is all they had, so it is what I got. To insulate the terminal, if desired, some heat shrink tubing can be slipped over before terminating. You might say this would have the advantage of examining the termination before covering, you can't see your crimped work on an insulated terminal.
Naaaa. you can see if a pre-insulated crip lug has been correctly crimped.
- It's ensured with a ratchet type, but all these type lugs have a window to inspect if wire has been inserted fully. Especially so with ring or fork types. Wire strands should viably extend past crimp barrel 1-2mm.
- The barrel crimp is a different shape to the insulation crimp, so you see if the lug has been incorrectly placed in the dies. [dodgy crimpers have same oval shape both ends and don't correctly shape the wire insulation crimp]
- An incorrectly positioned lug will have an obviously faulty appearance... not far enough in and half barrel crimped stands out bad.
- The shape of the crimp [oval] on a pre-insulated lug is far more reliable than the indent that can spread wide. Oval is fully contained in the die set.
- Incorrectly sized, like blue lug on a wire that should have a red lug will have an obvious mismatch at the insulation crimp end, being not closed down enough to be effective. Might look cool to have red lug on positive and blue on negative, but if the same gauge wire is being used one of these lugs is wrong.
- High QA Standard factories will have every crimper die set uniquely engraved, to track use if a dodgy connection presents during testing or 'in service' failure. An engraved mark is impressed into the plastic for certain ID of who did what. Common to weekly test crimpers too..... test by visual inspection of plastic and applied tension to wire when lug mounted in vice.
Just as an observation of lots of photos of projects here.... you guys don't seem to use the bootlace ferrule lugs much at all. Seen it many times here, wires terminated in the likes of screw down tunnel terminal blocks.
So much neater and safer using the colour coded plastic bootlace that fits around insulation at these terminations. Pretty ordinary when stretched insulation due to dodgy strippers creeps back with a bit of warmth in the case. Ferrules are far safer than using soldered wires in a compression terminal. Thats just nasty and very bad practice especially in a high vibration application.
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