Utilizing Nema Receptacles/Plugs with non-standard voltage

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Thendless

Member
Hi, I have a question about Nema receptacles and non-standard voltages.

I have some European equipment that requires 400V 3 Phase power. I require locking receptacles/plugs with this equipment and plan on feeding it via a 600-400V Transformer. I was thinking of specifying a NEMA L16-20 receptacle/plug which is meant for 480V 3 Phase. My question is are there any issue with using this for 400V Equipment or is only 480V allowed? My initial thoughts are that the receptacle will be fine with 400V since it is rated for 480V, so from that standpoint it is fine. However another purpose of these receptacles is to ensure that the incorrect voltage and current is not connected which is why they are unique for every combination of voltage/current rating.

Wanted to get others thoughts about this.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Welcome to the forum. The ratings are maximums.

Your plan is sound, especially if you do not also have 480v circuits and/or equipment using the same devices.
 

drcampbell

Senior Member
Location
The Motor City, Michigan USA
Occupation
Registered Professional Engineer
I'm not aware of a regulatory requirement preventing you from using a lower voltage, unless it's the "listed" catch-all.
At very least, I'd want to see a durable plaque at each receptacle saying "WARNING: Non-Standard 400 Volts, 60 Hz".
Are you sure your European equipment -- especially motors and motor-driven mechanical components -- will function OK at the higher frequency?
 

Thendless

Member
I'm not aware of a regulatory requirement preventing you from using a lower voltage, unless it's the "listed" catch-all.
At very least, I'd want to see a durable plaque at each receptacle saying "WARNING: Non-Standard 400 Volts, 60 Hz".
Are you sure your European equipment -- especially motors and motor-driven mechanical components -- will function OK at the higher frequency?

Funny you mention the 50Hz! I am aware of that and I am confirming that 60Hz will be fine with the Austrian manufacturer. I personally see no issue as the 400V 60Hz incoming line goes to a main disconnect, breaker and then directly to the VFD (Powerflex 525) which accepts the 47-63 Hz.
 

GeorgeB

ElectroHydraulics engineer (retired)
Location
Greenville SC
Occupation
Retired
@Jraef chime in here. I've yet to understand why someone would install an energy wasting transformer in such an application. The PowerFlex would actually be happier, IMU, with 480 in than with 400 in, programmed for the 400 motor parameters.

Is there a good reason beyond having a drive not rated for the input voltage?
 
Is there a good reason beyond having a drive not rated for the input voltage?

Because it's aimed at the European market which is 400/230v? And applying a higher voltage would be against the mfg's direction unless they approve of the difference.

And although it's not mentioned, it's possible that something else, like control power at 230v, taps off the input. Feeding a nominal 230v input with a nominal 277 is more that just a small over-voltage.

Or they may not want to support a programming change.
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
My understanding is somewhat different from LarryFine's: I believe that the NEMA voltages simply describe the terminal configuration, not the actual voltage rating of the device. While it is difficult to find datasheets, the few that I've seen described all the devices as having a 600V rating. It would not surprise me if some manufacturers build everything to 600V whereas others build only to the voltage associated with the terminal configuration.

The code requirement is that in a given facility, each different voltage (and I believe frequency and phase configuration) have a different receptacle pattern. There is not a code requirement to use NEMA configurations, simply that you use _different_ configurations. NEMA configurations are simply common practice.

IMHO this means that if you have L16-20 receptacles used at 480V in your facility, it would be a code violation to use an L16-20 for 400V. Also, while I don't believe you are required to use a 'higher voltage' configuration than your intended use voltage, doing so will mean fewer people questioning the installation, and it doesn't add significant cost.

-Jon
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
My understanding is somewhat different from LarryFine's: I believe that the NEMA voltages simply describe the terminal configuration, not the actual voltage rating of the device.
I don't really disagree with you. I meant it as a devices voltage use rating, not a voltage limitation.

After all, there's no real, physical difference between a 125v and a 250v receptacle of equal grade.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
I don't think there is a code issue unless you also use that same configuration for a different voltage.
406.4(F) Noninterchangeable Types.
Receptacles connected to circuits that have different voltages, frequencies, or types of current (ac or dc) on the same premises shall be of such design that the attachment plugs used on these circuits are not interchangeable.
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
Just curious why you don't use the standard IEC 60309 32A 380-415 V plug ? Eaton makes a 3 pole 4 wire AH463P6W.
I try to avoid mixing 400V with 480V because often you end up with both.
 
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