# Can I Use This Wire?



## bisley45 (Oct 10, 2015)

For the remote switches on a vfd ?


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## JimDawson (Oct 10, 2015)

Yup, it will work just fine.  You are only working with about 10 volts at a few mili-amps.


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## bisley45 (Oct 10, 2015)

that's what I was thinking thanks for the help.


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## 4GSR (Oct 10, 2015)

Cat 5 wire works too!!!!


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## Tony Wells (Oct 10, 2015)

If it subject to much flexing, Use CAT5/5E/6 jumpers. They are stranded whereas standard structured wiring CAT is solid, typically 24 or 23g.


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## British Steel (Oct 17, 2015)

That looks like parallel printer cable, exactly what I use (and obsolete, so plenty around for cheap or free!) - if you're keen to comply with regulations / code it *should* be physically separated from the high-voltage (e.g. incoming power, VFD to motor) wiring - which is sensible anyway as it's not insulated to the  same standard.
US code / UK wiring regulations require that any bunched cables are ALL insulated for the highest voltage present in the bundle, and separating them will reduce the amount of crosstalk between the VFD's noisy square-waves and sensitive control wiring (most VFD manufacturers highlight this in their installation guides too), reducing the risk of "incorrect operation".

Ideally the shield / screening should be earthed / grounded only at one end to prevent induction and earth / ground loops, most (all?) installation guides state that this should be at the VFD. a piece of heatshrink sleeving at each end's a nice finishing touch (for proper posh, whip a fresh wire around the shield/screen and solder (quickly) in place, bring it out from under the heatshrink to your earth / ground terminal.

If you have enough cores, it's nice to use a twisted pair to each switch individually too, as this again minimises the amount of induced noise on the VFD's input terminals, but that may be going a bit far for most folks - I'm a former pro-audio guy and also machine electrician, so I get a bit, er, anal? about these things


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## uncle harry (Oct 17, 2015)

British Steel said:


> That looks like parallel printer cable, exactly what I use (and obsolete, so plenty around for cheap or free!) - if you're keen to comply with regulations / code it *should* be physically separated from the high-voltage (e.g. incoming power, VFD to motor) wiring - which is sensible anyway as it's not insulated to the  same standard.
> US code / UK wiring regulations require that any bunched cables are ALL insulated for the highest voltage present in the bundle, and separating them will reduce the amount of crosstalk between the VFD's noisy square-waves and sensitive control wiring (most VFD manufacturers highlight this in their installation guides too), reducing the risk of "incorrect operation".
> 
> Ideally the shield / screening should be earthed / grounded only at one end to prevent induction and earth / ground loops, most (all?) installation guides state that this should be at the VFD. a piece of heatshrink sleeving at each end's a nice finishing touch (for proper posh, whip a fresh wire around the shield/screen and solder (quickly) in place, bring it out from under the heatshrink to your earth / ground terminal.
> ...



I wouldn't call following the rules anal. you've covered the basic requirements as required by code and addressed the insulation & cross talk issues very clearly & concisely.


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## middle.road (Oct 17, 2015)

+1 on what Harry wrote.


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## middle.road (Oct 17, 2015)

Dang, that's perhaps what I should have used on my setup last month. 
I've got a carton full of Comm cables & CAT5 cables in the basement...
I think I'll separate out the shielded ones and stash them for future use.


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## stupoty (Oct 17, 2015)

Cat5 loves to brake if its solid core, so make sure its got good strain relief at each end.  

Ive got it on one of my invertors and its been fine.  My invertors cut out if the go signal is removed so its not to bad of a failure mode if it does fail.

Stuart


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## Firestopper (Oct 17, 2015)

Is cat5 shielded? I never have cut one up.


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## Tony Wells (Oct 17, 2015)

Not normally. It is frequently labeled as UTP cable (Unshielded Twisted Pair) in addition to CAT 5, etc..


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## mksj (Oct 17, 2015)

This is computer communications cable (serial or parallel cable), which is stranded and very flexible. HDMI cable is also similar, but usually with different size wires and additional shielding on some of the pairs. As others have noted it will work fine for low voltage, and not in the same raceway/conduit as  high voltage wiring. Also as mentioned, ground the shield drain wire at the VFD only, and do not tie to the motor cable (which should be shielded and grounded at the VFD end only). Ideally one should use star grounding, where all grounds attach to a single point/post in the VFD box. There is often a metal ground plane with a ground point. The wires in HDMI/computer communication types of cables tend to be stranded, but quite small (usually 26 or 28G) and somewhat fragile so would us spades and pin jacks for the actual connections, along some heat shrink as a strain relief. Cat 5 and 6 can be shielded or unshielded, but twisted pair alone is not sufficient in a high EMI setting. I would recommend shielded cable for the control inputs. I tend to use 18-22G shielded communications cable because I find 26-28G too fragile unless it is in a molded or terminated cable. I would not use solid core wire in this setting because of fatigue and potential for breakage due to movement/vibrations in a machine environment.



I built a x axis VFD drive where I wanted to easily be able to separate the control box wiring. I used a computer serial cable which plugs into sockets at the VFD and control box. Wiring from the sockets at each end is 22G. Very inexpensive, the cable with sockets was around $6-8.


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