# 220 schematic requiring a neutral wire?



## sfsteel (Sep 16, 2018)

This is probably really basic, but I’m new to 220v wiring. This schematic shows L, N, PE. Picture attached.

I’m assuming:
L = Hot
PE = Ground 
N = Nuetral?

Where does the second hot in my 220v circuit go to? I didn’t expect to find a neutral connection on the schematic, rather two hots and a ground.


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## RJSakowski (Sep 16, 2018)

It looks like the schematic was for something similar to UK wiring.  Unlike our 240 wiring which is split  L1-N-L2, theirs is just L and N.  The P.E. is their earth or ground and is tied to the electrical chassis.  For US wiring, black would go to L and red would go to their N, and green or bare would go to PE.  Grizzly uses the same wiring convention on their G0755 mill which is a 240 volt machine.

If the cord in your hand is the power cord, I would color the insulation of the cord red with a magic marker so someone wouldn't mistake it for a neutral wire.  I do so on both exposed ends, the plug connection and inside the box where it connects to the terminal strip.


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## tweinke (Sep 16, 2018)

Im not going to attempt to answer your question but it might be good to post the make and model of the machine also.


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## sfsteel (Sep 16, 2018)

tweinke said:


> Im not going to attempt to answer your question but it might be good to post the make and model of the machine also.


It’s a precision Matthews PM30-MV

https://www.precisionmatthews.com/shop/pm-30mv/


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## sfsteel (Sep 16, 2018)

RJSakowski said:


> It looks like the schematic was for something similar to UK wiring.  Unlike our 240 wiring which is split  L1-N-L2, theirs is just L and N.  The P.E. is their earth or ground and is tied to the electrical chassis.  For US wiring, black would go to L and red would go to their N, and green or bare would go to PE.  Grizzly uses the same wiring convention on their G0755 mill which is a 240 volt machine.
> 
> If the cord in your hand is the power cord, I would color the insulation of the cord red with a magic marker so someone wouldn't mistake it for a neutral wire.  I do so on both exposed ends, the plug connection and inside the box where it connects to the terminal strip.



I only see the designated L1 as being fused though, if I connect the second hot to N, that would leave that line unprotected, right?


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## john.oliver35 (Sep 16, 2018)

sfsteel said:


> I only see the designated L1 as being fused though, if I connect the second hot to N, that would leave that line unprotected, right?


What RJ said.

In the US the second 'hot' would be protected by the breaker.  220 single phase breakers protect both poles.

Connect the PE (green) to the Earth connection on your outlet/box.  it doesn't carry functional current - it is your protection if something comes loose or fails in such a way that the chassis of the mill becomes 'hot'.


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## sfsteel (Sep 16, 2018)

john.oliver35 said:


> What RJ said.
> 
> In the US the second 'hot' would be protected by the breaker.  220 single phase breakers protect both poles.
> 
> Connect the PE (green) to the Earth connection on your outlet/box.  it doesn't carry functional current - it is your protection if something comes loose or fails in such a way that the chassis of the mill becomes 'hot'.


Got it, thanks for the input everybody!


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## tweinke (Sep 16, 2018)

If you have time you should post about what you think of your PM-30. Not a lot out on those machines.


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## sfsteel (Sep 16, 2018)

tweinke said:


> If you have time you should post about what you think of your PM-30. Not a lot out on those machines.


Oh I will, trying to get it powered up still!


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## Blackjackjacques (Sep 17, 2018)

sfsteel said:


> This is probably really basic, but I’m new to 220v wiring. This schematic shows L, N, PE. Picture attached.
> 
> I’m assuming:
> L = Hot
> ...



Everything about this schematic points to a 120V circuit and not a 220V.   The fact that L1 is fused only is a flag to me, as well as if you did put 220 V across L1 & N, you would also be putting 220 V across the hand controls (your E-Stop, On, Off) which isn't too cool according to NFPA 79 and others.    You need to double check beforehand.

Jim


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## Blackjackjacques (Sep 17, 2018)

john.oliver35 said:


> What RJ said.
> 
> In the US the second 'hot' would be protected by the breaker.  220 single phase breakers protect both poles.
> 
> Connect the PE (green) to the Earth connection on your outlet/box.  it doesn't carry functional current - it is your protection if something comes loose or fails in such a way that the chassis of the mill becomes 'hot'.



A 240 V single-phase breaker is normally two poles in the US -- meaning it would protect both legs.  Why would they incorporate a fuse in only one leg in a 240V appliance expecting to be wired across two legs?


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## macardoso (Sep 17, 2018)

Blackjackjacques said:


> A 240 V single-phase breaker is normally two poles in the US -- meaning it would protect both legs.  Why would they incorporate a fuse in only one leg in a 240V appliance expecting to be wired across two legs?



I work in electrical design for industrial control systems.  Typically all hot legs are fused or broken with circuit breakers. Neutral and ground should never have fusing.  Multi-pole circuit breakers are used here, which have connections between the poles to trip all legs if one goes. 

The risk with only fusing one legs of a 240VAC L-N-L system would be if the non-fused hot leg shorted to ground as there would be no breaker until the utility distribution (which is bad).

Call up Precision Matthews and get their input on wiring.  If they tell you to wire it that way then it is on them. Don't guess with electricity.


EDIT: I agree, if someone handed me that schematic, I would believe it to be 120VAC.  No one would call the second hot of a 240V line "N".


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## RJSakowski (Sep 17, 2018)

macardoso said:


> I work in electrical design for industrial control systems.  Typically all hot legs are fused or broken with circuit breakers. Neutral and ground should never have fusing.  Multi-pole circuit breakers are used here, which have connections between the poles to trip all legs if one goes.
> 
> The risk with only fusing one legs of a 240VAC L-N-L system would be if the non-fused hot leg shorted to ground as there would be no breaker until the utility distribution (which is bad).
> 
> ...


I would have thought so as well but here is the schematic of the Grizzly G0755 mill which is 220 volt only. You will notice that the same wiring designation is used.


There should be no path to ground of the unfused N leg as it is electrically isolated from earth the same as the L leg.  There is a danger of an unprotected short  between the unfused N leg and the PE leg.  Presumably, this would trip the circuit breaker though. Another possibility would be someone thinking because a fuse was blown that the machine was safe to work on but exposing ones self to electrical circuitry without disconnecting from the power mains is a fool's game by any measure.


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## Blackjackjacques (Sep 17, 2018)

Perhaps they are being lazy with their drawings and notes.  The convention showing L1 & N for 220V probably works OK in the UK and perhaps others since the voltage across L1 & N in the UK is 220V.  But the same applied here is causing confusion and certainly does not follow UL or NFPA.  What they should have shown for US applications is what RJ and others have noted. If the device is indeed rated for 220, you can apply 220V across the Black and White, with the White re-labeled with Red tape, etc.  Do not connect the utility neutral but do connect the ground to the enclosure, etc.  But there is still the problem of putting 220V across the hand controls which is a problem not only for NFPA/UL, but also the IEC.  So much for standards harmonization & globalization.


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## markba633csi (Sep 17, 2018)

I took a look at the PM30 specs and it is indeed listed as a 220 volt unit.  Could have fooled me tho.
I wonder if Matt is aware that the wiring colors are not really "code-ish"?
mark


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## mksj (Sep 17, 2018)

markba633csi said:


> I took a look at the PM30 specs and it is indeed listed as a 220 volt unit. Could have fooled me tho.
> I wonder if Matt is aware that the wiring colors are not really "code-ish"?



Just about every single phase Chinese/Asian mill run on 220V comes either wired with a Black, White and Green or Brown, Blue and yellow/green wire cable, i.e Hot, Neutral, Ground. The machine's are not wired for US specifications, they are for ROW (Rest of World).  If you look at most "universal voltage power supplies i.e. 90-240VAC input" they all have a N and L1 input connection.

It is unfortunate that the mill manual is not clear on this, but US electrical code allows you to use a white wire if it is marked with some red tap at either end denoting a hot leg. It with be worthwhile that when the machines are shipped to customers that the power cable is marked as to connections.  I would also prefer that both hot  legs are fused for safety reasons, but agree with RJSakowski, only a fool would works on the wiring without disconnecting  the power at the panel. I get kind of paranoid on this and one can never be too safe. Made my share of "thought I disconnected that circuit" and been electrocuted enough times to have learned my lesson and am still be alive to talk about it.


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## tq60 (Sep 17, 2018)

First off this device being built off shore is likely built as universal meaning it can be shipped anywhere any time with minor things like just a motor different depending on where it may land.

That being stated...

The internal configuration shows only one fuse which is fine.

That fuse is in series with the load and can go anywhere that an open will remove the load from the line.

The LOAD CENTER however is where a breaker for each current carrying wire is needed.

The device is not split phase or in need of neutral so the 3 wires are L1, L2 and safety ground.

Green is almost always that...check it with ohmeter.

Black is usually L1 and white is usually neutral but can be used as L2 and it should be marked with a red band of something but most understand both white and black are current carrying.

Sent from my SAMSUNG-SM-G930A using Tapatalk


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