Which thickness CY cable do I need for 1.5kW spindle?

[A_Camera]

Ok it is not lamp wire it is CY cable the smaller size is easier to connect into some of the small plugs and cable trays.
I see the chart you put up that is for domestic wiring and I agree with that.

The 1.5Kw is spread over the three cables as well.

But it is your opinion but not mine. I do use 1.5mm generally.

I call it lamp wire because the conductor is as thin as it is for lamps. The fact that it is shielded is a different matter. I chose 1.5mm2 for the power and 0.75mm2 for the control and low voltage wires. Admittedly, it was not that easy to fit the 1.5mm2 into the plug, but it is just a one time work, so once it is done in one end, everything is much better and easier. Crimping is simple and no bother at all. If the wires are too thin crimping cables shoes becomes insecure and problematic.

[paulus.v]

I call it lamp wire because the conductor is as thin as it is for lamps. The fact that it is shielded is a different matter. I chose 1.5mm2 for the power and 0.75mm2 for the control and low voltage wires. Admittedly, it was not that easy to fit the 1.5mm2 into the plug, but it is just a one time work, so once it is done in one end, everything is much better and easier. Crimping is simple and no bother at all. If the wires are too thin crimping cables shoes becomes insecure and problematic.

Do you have a hair dryer at hand? Check the cable and power. Mine has 1700W and a 2x0.75mm2 cable. And is german made.


Now regarding the question in this thread, I would never use a 0.75mm2 "normal" stranded cable in a CNC machine. Since all the cross-sections are composed of thin wires with the same diameter, a larger cable will last longer. If/when half the wires of the 0.75mm2 conductor (only 10-12 of them) will be broken, probably the rest will blow. For a 1.5mm2 cable, three times the number of wires needs to be broken to come to the same situation.

Using special flexible fine stranded cables, even 3x0.5mm2 will be enough for a 3 phase 1.5kw spindle on a short distance

Here I attach some more charts...

[A_Camera]

Do you have a hair dryer at hand? Check the cable and power. Mine has 1700W and a 2x0.75mm2 cable. And is german made.

Fine. Now, run that hair dryer for 8 hours non-stop and see what happens...

Hair dryers are NOT high frequency controlled equipment, they have a tiny motor and they are not designed to be run for more than a few minutes a time so you can't really take that as a good example. My drilling machines have 1.5mm2 cables, they are also German made, and none of them are over 1kW. Why? Because they are designed for sudden current rushes and for long usage time.

Now regarding the question in this thread, I would never use a 0.75mm2 "normal" stranded cable in a CNC machine. Since all the cross-sections are composed of thin wires with the same diameter, a larger cable will last longer. If/when half the wires of the 0.75mm2 conductor (only 10-12 of them) will be broken, probably the rest will blow. For a 1.5mm2 cable, three times the number of wires needs to be broken to come to the same situation.

That is yet another good argument for a stronger cable. On the other hand, if you handle the cable as you supposed to handle and don't bend it more than it is specified for *AND* use the cable type which is designed for the application (i.e. flexible cable chain use) than you should not have any broken wires during the life time of your machine. Remember that I am talking about quality cables, not the one used in the hair dryer.

Using special flexible fine stranded cables, even 3x0.5mm2 will be enough for a 3 phase 1.5kw spindle on a short distance

Yes, of course. I have never claimed otherwise. Just that I can't really see any *GOOD* reason for not using something stronger than 0.75mm2. Never the less, there is a group of people who prefer the easiest approach, which is using the thinnest possible cables. Beats me why, I don't understand that philosophy and prefer to have margins if I can. On the other hand... so far I have not had any electrical issues, and I don't expect to have any later on.

[Clive S]

Yes, of course. I have never claimed otherwise

I thought you claimed it here:-

It is thinner and lighter but it should be 1.5mm2. 0.75mm is OK for control signals but actually too thin for the power

Well you appear to have jumped on the op's post nearly 3 months after he last posted and muddied the waters quite well.

I think you need to take a good look at your own machine before nit picking others.
I will not be posting any more on this subject. So please lets not take any more space on his post.

By all means start one of your own.

[A_Camera]

I thought you claimed it here:-


Well you appear to have jumped on the op's post nearly 3 months after he last posted and muddied the waters quite well.

I think you need to take a good look at your own machine before nit picking others.
I will not be posting any more on this subject. So please lets not take any more space on his post.

By all means start one of your own.

Sorry for disturbing the peace, but the way I see it is that I was not the one throwing the mud. I made a short one line comment and not criticized you or anyone else, all I said was:

It is thinner and lighter but it should be 1.5mm2. 0.75mm is OK for control signals but actually too thin for the power.

Actually, going by the book (the manual of my VFD), even that statement is wrong because for the 1.5kW the cable should be 2.5mm2 but that is simply too thick and really over engineered, so 1.5mm2 is more realistic.

The thread would have been dead by now but apparently you, and some other people could not stay away from it, so it lives on. I don't mind that, but it would be more useful if people could keep their heads cool and would not throw mud just because I don't follow the stream and have a different opinion. I was also NOT nit picking on other people's machines, but you have to remember that this forum is visited by many total newbies who experience a lot of electrical issues. One way of helping is to give factual advice, not emotional.

BTW, Why are you saying that I need to take a good look at my own machine? I am looking at my machine, and regarding electrical installations, I am not only using several DVMs but also an oscilloscope, and in fact, occasionally two oscilloscopes at the same time. Apart from that, I am reading the manuals of every item that comes with a manual, not just guessing and go after what other people use or claim on the internet. Never the less, I could have missed something, so if you have found something wrong please let me know. I am in the process of upgrading and welcome all comments. I have no emotional attachments to my machine so I am ready to change almost anything if it is for the better.

You are though right about one thing, there is not much more to say about the subject, though it may pop up again, or someone might start a new thread with the same question...