# Should a VFD always be in an enclosure?



## HMF

Home Depot no longer carries a 6x6 enclosure that I wanted to use for a VFD.
I can get one elsewhere, but I want to know if you guys think an enclosure is a must
because then I may need a fan to keep the VFD cool, right?

What size do you guys recommend? I thought 6x6 NEMA was what I needed?
Also, how do you cut the holes for the face of the VFD to go though?

Thanks,


:tiphat:Nelson


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## 8ntsane

Hi Nelson

For a VFD enclosure, if I remember right, has to be 4-times the size of the VFd
A 6x6 sounds kind of small. Any of the boxes out there would need ventilation somehow. I have a 7.5hp and a 5hp  Teco FM500 models, not the fm50. But they both came in enclosures, the enclosures are very large, and have vents all over them, with built in fans. Your VFD manual might suggest what size is proper for your VFD.

As for cutting the holes for the face, you could measure it out, drill holes in the corners, then jig saw the rest. There was a VFD install thread here a few days back, where the guy added a air filter to the enclosure too, I thought it was a good idea. More importantly, make sure its vented well enough not to cook your VFD, and make sure it has some thing to keep chips out. Mine look like they have a screen behind the vent cut outs.

Paul


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## Kennyd

Mine is just on the wall, out of the way from coolant or flying chips.  A enclosure is not "needed".  I can't see how 6x6 would be big enough anyway?


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## bcall2043

Nelson,

Paul and Kenny made valid points above. 

Not sure about what you are planning but the VFD that I have came without a NEMA enclosure but install instructions called for one.  I asked an electrical engineer buddy about it. He pointed out that the wiring connection points for my VFD do not meet code without the enclosure. The bare connection points can be reached with a small pointed object. If I remmenber correctly the 4 times size with a fan sounds about right. 

Benny


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## 8ntsane

If you think you have any chance of dust, chips, or coolant getting to your VFD, you can allways build a small cabinet made of wood to put it in. Gives you the option of size, vent location, and options for mounting the fan if used.

One of my Teco FM500 units are mounted on he wall, and I glad it has the nema enclosure. I find chips sitting on it all the time. But my shop is a 1-car garage, and very congested.

I built a wooden enclosure for the service panel in the basement last week. I used 1/2 thick materials. Picked the wood up at home depot, they even cut it all to size for free. A few hinges, and a package of screws, and less than a hr later, It was done!

Just another idea for you

Paul


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## HMF

Kennyd said:


> Mine is just on the wall, out of the way from coolant or flying chips.  A enclosure is not "needed".  I can't see how 6x6 would be big enough anyway?
> 
> View attachment 33694



Kenny,

That is a very neat setup, but I have a couple questions.

You have one conduit coming into a flip switch- is that the power going in? (220?)
Then you have a BX box with two conduits coming down- (watertight conduit?). One goes to the motor no doubt.
Does the other go to a remote control box?

Thanks!

Nelson


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## Tony Wells

I would definitely run an enclosure. NEMA covers many types of enclosure, depending on the environment the equipment will operate in. If you run a fan, and I would, make sure you have sufficient inlet area to allow flow commensurate with the capacity of the fan, plus an allowance for the filter restriction. I wouldn't hesitate to use an 8 x 8 x 4, or even larger. You also will probably need to build a power supply for the fan, unless you are planning a 110/120 VAC muffin fan. That would be preferable, but not always easy to find. Ebay I guess.

I have run a totally sealed metal Hoffman enclosure, with a large Variac running 2 500w cartridge heaters. The fan was mounted on standoffs to blow down over the Variac. Doing this without  vent simply dissipated the heat over the entire enclosure by warming up the air inside to an even temperature. Monitors showed it operating within design parameters, even in 110 ambient. Plus, it was sealed against ingress in a corrosive atmosphere, both in a fertilizer packaging plant, and Morton Salt packaging operations. 


For reference:

http://www.nema.org/prod/be/enclosures/upload/NEMA_Enclosure_Types.pdf


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## HMF

Paul,

I bought a 12x12 NEMA at HD a while back when they had them- cost me about $25. But it looks so large next to a VFD.
The box has a cover somewhere, but I would likely cut a piece of acrylic plastic, so I could see it.
(see pix)
View attachment 33700

Also bought a Murray 2-wire disconnect- I think it is 30 Amps at HD.
View attachment 33702
View attachment 33703


The original pushbuttons are shown in the NEMA.
View attachment 33701

The main house panel is also shown- I need to upgrade to 200A and a bigger panel.
The electric service is in an alcove where I shove the small mill (Burke #4).
View attachment 33705

	

		
			
		

		
	
0
	

		
			
		

		
	

View attachment 33704


My tiny shop area is right near the service which is good.
I figured I would have the sparky upgrade the service and box, hook up my new basement lines and install 2 or 3 220V 30A lines for the machines.

Nelson


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## Bobby Bailey

Mine is set up just about like Kennyd's. I saw no need for an enclosure in my situation.
Bobby


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## bcall2043

*Adding photo and note*



bcall2043 said:


> Nelson,
> 
> Paul and Kenny made valid points above.
> 
> Not sure about what you are planning but the VFD that I have came without a NEMA enclosure but install instructions called for one.  I asked an electrical engineer buddy about it. He pointed out that the wiring connection points for my VFD do not meet code without the enclosure. The bare connection points can be reached with a small pointed object. If I remmenber correctly the 4 times size with a fan sounds about right.
> 
> Benny



Nelson's post with photos reminded me that my buddy also gave me a NEMA enclosure that was a take-off modified to let the drive controls stick out. I plan to add plexiglas to keep it clean inside as my drive is much smaller.

Benny


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## brucer

here is what my vfd setup looks like..
[video=youtube_share;Ja5CZHVRM8U]http://youtu.be/Ja5CZHVRM8U[/video]

 My vfd doesnt run hot the way it is moounted in the enclosure, I do plan on adding a filter on the bottom and a fan in the top corner to create a cross flow to make sure it doesn't overheat if i'm running hard..  my tig welder doesnt mess with the vfd the way it is..


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## Kennyd

*Nelson:*

Kenny,

That is a very neat setup, but I have a couple questions.

You have one conduit coming into a flip switch- is that the power going in? (220?)
Yes, that is correct, that is a 2-pole switch breaking L1 and L2 of the main feed to the VFD
Then you have a BX box with two conduits coming down- (watertight conduit?). One goes to the motor no doubt.
Correct, one directly to the motor, remember no switches between the VFD and the motor.
Does the other go to a remote control box?
It goes to the drum switch with is original to the machine, I just rewired it for low voltage.

I posted some close up pics in this thread: http://www.hobby-machinist.com/show...e-off-forward-switch-to-vfd?p=26771#post26771


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## HMF

Kenny,

Looks like you used shielded 4 or 6 connector 18 gauge wire from the VFD to the drum switch.

When you "break" the two lines to the on/off switch, as in Jim B's example, do you do that before the VFD, because you arent supposed to have switches between the motor and VFD.


Nelson


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## Kennyd

Allthumbz said:


> Kenny,
> 
> Looks like you used shielded 4 or 6 connector 18 gauge wire from the VFD to the drum switch.
> 
> When you "break" the two lines to the on/off switch, as in Jim B's example, do you do that before the VFD, because you arent supposed to have switches between the motor and VFD.
> 
> 
> Nelson



It is #18 shielded  3 conductor, Black, White and Red.  The Green wire is soldered to the shield under the heat shrink and then grounded.  You only need 3 wires to each "remote" function.  The wire type here is not critical, so use whatever.

Yes, the switch breaks the main feed TO the VFD,  Is #12-2 wire on a 20 amp 240v circuit.


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## rdhem2

Mr. Nelson;

As far as cutting holes in a electrical enclosure.  I see you list a drill press and two mills in your shop.  Put them to use.  If I am correct, they will put any size and shape hole anywhere you want at any time you want.


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## rdhem2

Nelson said:


> Kenny,
> 
> 4 or 6 connector 18 gauge wire from the VFD to the drum switch.
> 
> Nelson



Please guys, I don't understand.  Why do you insist on using a drum switch when the VFD provides the reverse function.  The Drum switch is not UL approved as a disconnecting device either.  Just deep six it, make it simple.  Remember the KISS principle.  A toggle switch is not approved as a disconnect either unless horsepower rated.  Most aren't unless you get the $10- $12 models, which I doubt.  Just get a motor rated switch with ears for a padlock on the cover, or some other lockable device.  Mount it as the first device in the circuit and then *USE IT*.

Engineers and code designers, the last time I checked, don't spend their time writing requirements and instructions for their health.  There is a good reason apprently way over our heads.  *YES, AN ENCLOSURE IS REQUIRED WITH A VFD UNLESS SPECIFICLY STATED TO BE OMITTED.* I only know code, not the reasoning behind it.  Have a good day, and be *SAFE.*​  Is your or someone elses life worth that extra $10?


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## Kennyd

rdhem2 said:


> Please guys, I don't understand.  Why do you insist on using a drum switch when the VFD provides the reverse function.  The Drum switch is not UL approved as a disconnecting device either.  Just deep six it, make it simple.  Remember the KISS principle.  A toggle switch is not approved as a disconnect either unless horsepower rated.  Most aren't unless you get the $10- $12 models, which I doubt.  Just get a motor rated switch with ears for a padlock on the cover, or some other lockable device.  Mount it as the first device in the circuit and then *USE IT*.
> 
> Engineers and code designers, the last time I checked, don't spend their time writing requirements and instructions for their health.  There is a good reason apprently way over our heads.  *YES, AN ENCLOSURE IS REQUIRED WITH A VFD UNLESS SPECIFICLY STATED TO BE OMITTED.* I only know code, not the reasoning behind it.  Have a good day, and be *SAFE.*​  Is your or someone elses life worth that extra $10?



In my case, the drum switch is just used as a low voltage switch to remotely control the VFD, and that is the way most are used in conjunction with VFD's.  As to why we use them?  Well sir that is simple....they are already on most machines when we get them and they work perfectly for the purpose.

Nowhere in my VFD manual does it say that an enclosure is "required".

You sir need a little more tolerance and accept the fact that there sometimes is indeed "two ways to skin a cat", your way is not the only way sometimes. Dredging up one year old posts to try to get your 2c in is not going to make any friends around here.


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## Hawkeye

I built an enclosure with a fan and filter for my FM50 because my shop is too small to have a separate cutting/grinding room. There is metallic (conductive) dust everywhere. That is notoriously bad for anything electronic. The front of the VFD is visible through a lexan window. Control is done with remote inputs.

There doesn't seem to be much advantage to an enclosure if the front is open, unless the fan is blowing in (positive pressure, blowing out around the face). That is contrary to the diagrams in the FM50 manual.


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## rdhem2

I apologze Mr. KennyD.  My limited knowledge only comes from operating a shop building custom electrical enclosures and control wiring under UL supervision for 32 years.  Just because it works does not mean it is right.  Silly codes and rules.


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## mitsue

rdhem2 said:


> I apologze Mr. KennyD.  My limited knowledge only comes from operating a shop building custom electrical enclosures and control wiring under UL supervision for 32 years.  Just because it works does not mean it is right.  Silly codes and rules.




Easy there big guy. Enclosures are rated for different enviroments that the equipment will be used in. Some are for wet enviroments while others for dusty or areas where fumes causing explosion hazards exist. It is good advice to use some type of enclosure when the possibility of metal chips or moisture is a concern. Also the point of covering the terminals is a good idea. Thats why the same drives are available in different rated housings. You analyze the site conditions and pick the right type to begin with. It may be good for your business but not every situation requires an enclosure. Most manufactures specify four times the area for sizing an enclosure for heat dissipation.
Darcy


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## zimma

Here is what I did with mine. Mounted VFD with line filter in a sealed box on the side of the Mill Stand. Wired in remote control panel for operating mill. The enclosure was cheap on ebay. Control panel was home made using boxes and switches from ebay. Never have to open the box to the VFD. Heat buildup hasn't been an issue.


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## WDG

Being new to this forum, my two cents isn't worth much.  Having said that, I'm going to throw it in anyway.  I've had a VFD for over a year and I mounted it right on my mill drill.  It's up high and away from any crud or chips.  There is a small fan that keeps it cool.  I wouldn't think of putting it in an enclosure.  I'm going to buy another one for a knee machine and surface grinder I just got.  Nope, not going to put them in an enclosure.  I want them where they can get plenty of air.  I may be wrong but it's my dollar and I want them to stay as cool as possible.


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## joe_m

WDG - your two cents is worth just as much as mine, and I've been babbling along here for a few months.
Both of my VFDs are out in the open for the exact same reason you mention - so they can stay cool when my non-air-conditioned shop hits 100 in the summer. I figure as long as I don't use it as a rest for the coffee cup, and keep the swarf from flying into the top, then it should be safe.

Joe


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## rwwells

Mine is sorta,,,,,,,,,,,,,maybe not,,,,,,,,,,,,,,see for yourself






RWW


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