Wire size for 220 spindle

[cruser56 (Kenneth Baker)]

What wire size are people using for 220 spindle. 10ga gets me 30amp, 12ga gets me 20amp. From what i gather the 20amp should be good it will be dedicated plug

[poppyscott (Don Scott)]

20 amp is adequate for a spindle.

[cyberreefguru (The Guru)]

According to the PWNCNC website, their 220v spindles are rated for 10amps; 12awg should be more than sufficient.

1.5kw 110v Motors draw 12A while 2.2kw 220v Motors draw 10A

Though @Aiph5u says his 2.2kW spindle draws 24A, so 10awg would be required.

YMMV.

Follow your local code

-Tom

[Aiph5u (Aiph5u (not affiliated with Onefinity))]

Hey Kenneth,

it depends on what cable do you mean, the VFD input cable on a single-phase input VFD has usually much stronger cross-section area, while on the spindle cable, which is a shielded 3+PE cable at the output of the VFD, you have the power spread over the three wires, each sinus wave shifted by 120°.

These informations have to be read in the VFD manual. For my 2.2 kW 220 V single phase input VFD I use 2+PE x 4.0 mm² (recommended: 10 AWG) and for the spindle cable I use…

@Aiph5u

…shielded 4 x 2.5 mm² (3+PE) (approx. AWG13) (LAPP cable No. 0026271)

@Aiph5u

Note that in engineering, wires are not measured in wire diameter (as in American wire gauge), but in cross-section area, because the cross section of a wire is directly proportional to its strength and weight, and inversely proportional to its resistance. The cross-sectional area is also related to the maximum current that a wire can carry safely. Wire diameter rp. AWG is not.

There is a nice Comparison chart for American Wire Gauge to IEC 60228 in this file:

• Comparison of SWG (red), AWG (blue) and IEC 60228 (black) wire gauge sizes from 0.03 to 200 mm² to scale on a 1 mm grid – in the SVG file, hover over a size to highlight it

For the VFD output which is the spindle cable, …

@Aiph5u

…I use LAPP ÖLFLEX® CLASSIC FD 810 CY, in the strength 4 x 2.5 mm² (LAPP #0026271) for the 2.2 kW spindle or 4 x 1.5 mm² (LAPP #0026251) for a 1.5 kW spindle (=shielded 3+PE).

@Aiph5u

• On the output of the VFD, i.e. the spindle cable, you should use shielded 3+PE for the three-phase spindle, like shown here:

Image 1: A typical spindle cable for use in a power chain (LAPP ÖLFLEX® CLASSIC FD 810 CY)

See this thread for more information.

@Aiph5u

Note that even if PE wire and cable shield are both connected to ground, they serve two different purposes. PE is crucial for electrical safety, and shield cannot replace the PE wire!

Therefore the reference to “16/3” in the topic’s title is dangerous: NEVER connect a spindle without a PE wire ! Shield cannot replace a PE wire!

@Aiph5u

Also you should know that on chinese spindles, the power rating is often wrong (see here for example).

Note that should you really buy one of these cheap chinese kits, you should → read this to make your life easier.

@Aiph5u

You can buy Daniel Moran’s @PwnCNC ready-to-use spindle cable here.

[Dr-Al (Alex Zeller)]

What wire are you talking about? If you are installing a new breaker and wiring to an outlet then you should follow the code. If you are talking wiring a cord from a VFD to plug into an outlet then the code doesn’t apply (10 gauge = 30 amps, 12 gauge + 20 amps, etc.). Or are you talking about the wired from the VFD to the spindle? What size spindle are you planning on using? What voltage?

[Aiph5u (Aiph5u (not affiliated with Onefinity))]

Hey Alex,

of course, I refer to the cable between the NEMA or IEC socket, and the VFD, as “VFD input cable”, and the cable between the output of the VFD and the input of the spindle as “spindle cable”.

The installation between the wall power box and the NEMA or IEC socket is to be done according to the regulations and standards in your country. I just mentioned it to say, usually 240 V is already there, you just need an electrician to install a MCB and a socket.

[Dr-Al (Alex Zeller)]

The wire between the socket and VFD doesn’t need to be 10 gauge if the maximum draw is 30 amps. In the US, the wiring code rule of thumb everyone refers to is 12 gauge for 20 amps, 10 gauge for 30 amps, etc. But that’s not true. That’s for copper wiring between a breaker and an outlet. It’s also a worst case assumption. The code assumes the wire will be ran inside a wall, other wires will also be ran next to it in a wall, that one of the terminations could be only rated for 60c, etc. The NEC, rightfully, assumes that it’s better to be safe than sorry.

If 90c wire is used then the code specifies that 12 gauge copper wire could be possible for 30 amps. If you are using aluminum 60c wire it’s only rated for 15 amps. If you’re wiring up a VFD with a cord to plug into an outlet then most likely it’s 90c wire (since both 60c and 75c have been phased out of production) the code will most likely allow for 12 gauge wire.

Going with 10 gauge doesn’t really add any safety either. The only risk is the wire heating to the point the insulation will melt. As long as the wire isn’t some counterfeit Chinese stuff a 30 amp breaker will not allow enough current to flow through the wire to heat it up beyond it’s limit. If you rummage through your grandpa’s spare electrical connectors you very easily could grab a male plug that’s only rated for 60c (which could over heat).

Some common sense still needs to be used. For example electrical cords shouldn’t be covered with something that can easily catch fire. Cords shouldn’t be placed where they can’t dissipate heat. This is why tools that come with a cord installed often will have a cord gauge smaller than what the rule of thumb will allow.