CNC Newbie needs advice and Guidance

Hello all. I’m a Newbie to the CNC world of things. This past November I bought the Elite CNC. I enjoy creating things with wood so I have quite a few big machines. That being said I have a few questions that I want to make sure I set this up right. For the spindle I will be going with the 80mm @ 2.2kw. So, I just want to make sure the power that will be needed is installed. I have already a few 220+v, at the high end of a 60amp which is for a welder. I have not purchased the spindle nor the VFD yet. Will someone give me some help letting me know how much power (breaker size/type) I will need installed at the panel box and the outlet type. I can have the electrician install it for me. I live in the state of Utah.

For the VFD I believe I will need: 200-240v, 12amp, 3hp, Single or 3-phase??

I was thinking about buying a Delta, Hitachi type of VFD.

I already have a control ip66 panel box for the VFD to place in.

Any suggestions are more than welcome for this Newbie. Tks

Hey Christopher,

if you want to run a 2.2 kW spindle on a single-phase circuit with 240 V, then your VFD will be rated to up to 24 A at its input and the recommended fuse will be 30 A (see here for an example of a wire and fuse size table in my VFD manual).

Are you in North America? If so, in most cases you will have split-phase electricity with 120/240 V which means you need a VFD with 200 V class single-phase input and you would need a NEMA 6-30 outlet or a NEMA 14, with a 30 A circuit breaker, for the single-phase input, 2.2 kW 200 V class VFD.

In case you have three-phase electricity with all of the three phases of 208 V made available, then, and only then, you could also buy the 200 V class three-phase input VFD model. This would mean you need smaller wires at the VFD input and a smaller circuit breaker, but a triple contact model then. Should you really have 208 V three-phase, the connectors that are used internationally are the IEC 60309, here they write that in the USA they replace the older American-style three-phase connectors in the last 30 years.

The third possibility, a 400 V three-phase VFD, is for regions where you have 400/230 V three-phase electricity (e.g. Europe)

In any case, I would always recommend to buy a ready-to-use spindle cable with the spindle from the spindle manufacturer (reputable spindle manufacturers always offer this). This is because either you buy an industrial spindle which have an industrial circular connector for which you need an expensive crimp tool (may cost more than the cable) OR you buy a cheap chinese spindle which will come with what they call “aviation connector” in loose form with a piece of cable which is usually too thin for the current and not made for a shielded power cable and it is impossible or at least extremely difficult to fit an appropriate cable into those inappropriate connectors, and additionally, they are for soldering but soldering such a connector is not for beginners. Therefore if you don’t go the route to buy a serious industrial spindle with ready-to-use cable from manufacturer, I recommend to buy a cable ready-to-use for those cheap chinese spindles that are available here.

By coincidence, I just wrote this answer this morning which may overlap regarding content :slight_smile:

Welcome to the forum!

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I have an Elite series on order as well and live in Southern Utah, where are you located?

Up north Salt Lake area. Good to know I’m not he only one here. lol

Awesome, thank you so much for the advise which will be put to use.

Got it…

No one else recommends anything above 15A for a spindle/VFD that maxes out about 10A draw @220v. My brewery uses about 30A max and there’s no way any spindle that can be attached to an 80mm mount and supported by the 1F can draw even close to its power.

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Hey Christopher,

I would always recommend a VFD that has Sensorless Vector Control which is the case e.g. with the Hitachi WJ200, the Omron MX2, the Hitachi S1, and the Invertek E-3, and with many serious VFDs more.

If you choose the Hitachi WJ200 or the Omron MX2, which are excellent VFDs, you got to know that they are both practically identical. All the settings and options are identical and also the manuals have the same content (with extremely little exceptions) (Omron MX2 User’s Manual, Hitachi WJ200 User’s Manual).

The right model for single-phase 200-240 V input for driving a 2.2 kW motor is called either

and the WJ200 equivalent is called

Be careful to choose the right model if you have split-phase electricity (240 V), since you got to buy these models which receive their power over one single phase.

Only buy the three-phase 200-240 V input model if you are sure you have three-phase 208 V with all three phases accessible in your panel box.

Here you can see the nameplates of the single-phase models (I own the Omron). One difference is only the maximum frequency, which is 580 Hz on the Omron MX2, but this is only necessary for spindle speeds of up to 35,000 rpm (which are very expensive spindles). With 400 Hz you can drive the usual 24,000 rpm spindles.


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But there are hundreds more.

No one in North America has 3 phase in the home, you’ll find that in only commercial and industrial spaces and then only if you request it installed or it was installed by the previous owner/tenant. Most commercial spaces can’t even have it installed.

It sounds like in your previous reply you might be looking at the maximum input current of the VFD without taking into consideration what spindle is being connected to its output.

Hey Espressomatic,

look, Espressomatic, neither you follow the references I always provide, nor you are attentive. Here we were talking of VFDs for single-phase input. That is exactly what is available as domestic electricity in North America (as you correctly state) since you have split-phase electricity in domestic areas.

You forcibly need a VFD to run a spindle, because a spindle is a three-phase asynchronous induction motor (called “spindle” here) and such a motor forcibly needs three-phase electricity. And a VFD is a device that creates three-phase electricity. That’s what it does.

You didn’t forget that when a spindle is rated with 10 A and a VFD with 10 A output, that a VFD produces three phases at the same time? So when you draw these currents from one single phase supply circuit, what do you think to what that the input current then forcibly arises?

This is physics, not magic. If you want to know, the formula for the three-phase motor is here and you still will have to add the efficiency of the VFD itself. But I am sure that people like you are not interested in these facts, and that you won’t even look.

Look, you’re just embarrassing yourself here with your alternative facts instead of reading up on the facts I always reference, which are available for everyone to read and verify. You better stop before you embarrass yourself even more.

Precisely. The VFD mentioned above is rated 24 A input current (and the fuse recommended as per the VFD manual 30 A for this reason, as you need a few percent reserve) because it is made for the case that at any time, you attach a spindle that is rated 12 A on three phases to it.

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I think you need to take it down a notch, I really don’t appreciate the attitude. Maybe something’s lost in translation and that’s fine, but the response is certainly not.

I was replying to this specific sentence:

You also said

And I’m just letting you know that it’s not in “most cases” it’s in all cases for North America.

The OP is most certainly not going to have a spindle that maxes out your particular VFD, nor is he likely to use your VFD. He can most certainly get along with a 20A 240V circuit, using a very common NEMA 6-20 receptacle and plug with any of the many spindle/VFD kits being sold by for example pwnCNC and others.

In light commercial, commercial construction, and industrial areas in North America, you can find 208 V three-phase electricity (with 120 V between each hot and neutral). The three-phase 200 V class of VFDs is made for 208 V three-phase electricity. They are for the American market, since there exist 208 V three-phase mainly only in countries with 120 V on single phase.

The original poster stated to want to use a 2.2 kW spindle on a VFD at 220 V, and it is not questioned that this shall be used on a single-phase supply circuit. The data I gave refer to exactly this.

It violates the electrical safety regulations of your country to connect an electrical appliance to a supply circuit that is not appropriate to the rated current. Recommending this is irresponsible and testifies to cluelessness and lack of conscience. One more word and I flag your post.


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The nameplate rating of the VFD would only be used if the manual does not contain specific information on overcurrent protection and conductor sizing (such as the tables that Aiph5u referenced above). When using the nameplate per NEC 430.122(A) you would be required to size the input conductors and overcurrent protection at 125% of the rated nameplate value. There may be cases where the 125% calculation yields a result of say 40A yet the manual shows a overcurrent protection of 35A or possibly 60A - the manual is the law in that case. I get the point that the spindle likely would never require that much current but the NEC disagrees, their primary objective is to prevent fires and will generally err on the side caution. It is also not a universal answer to just go big on the input overcurrent protection because the VFD components themselves are designed for a specific max input current. You can in theory over size the input conductors if the overcurrent device (circuit breaker or fuse) this would typically be documented in the manual and may be restricted by the lug size on the VFD which may be rated for #4 to #10 wire for example.

I had a case where I was hired to replace a VFD that had an input of 40A with one that had an input of 50A even though the motor it was driving remained the same, I was required to replace 200 feet of wire back to the panel as well.

One of the main challenges with many of the cheap VFD out there is they have little to no documentation, if the do it’s likely not really properly validated/tested/listed (the manual data is probably copied from whatever VFD hardware they attempted to copy while taking out all the expensive components to get the cost down :wink: )

I’ve tested my 220v 2.2kw spindle using a CT clamp and scope on the input side, with a 5 second ramp time set the highest current draw I observed was 9 amps, with the typical running around 4A (FWIW where I am is somewhat of an outlier, my voltage typically measures between 252 and 258 here, electric co says it’s within their spec and won’t change the tap on the transformer). I wired mine with #10 wire and a 20A circuit breaker which is likely smaller than it should be but I have never had an issue with the setup. I used #10 because it would allow me to go to a 30A circuit breaker if I really had to (ignoring any de-rating of the conductors for continuous use per 210.19)

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