Decreasing the size of the grounding and/or grounded conductors.

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roc_clmbr

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I am trying to find in the NEC 2011 when I can use a smaller size Neutral or Ground wire in a Circuit. For instance I am wiring a 240v 50 amp pressure washer receptacle. I pulled 2- 8 gauge Blacks and 1- 10 gauge Green. Is this OK? At what wire size or Amp rating can I change sizes. Thank You
 
No. I did it at work. I am an Apprentice and my Journeyman saw me pulling the wires and asked me why I did it. I asked him if it was OK and he told me to look it up in the code book. Im assuming its not since he looked at me funny. Thats his way of teaching me how to use the NEC. I have looked all over in the book and cant find the answer. I have to know by Monday so I can fix it or not.
 
If this is in a metallic raceway like EMT the see 250.118 as to the raceway being allowed as the EGC, but if your are installing also a wire type EGC it must meet the requirements in table 250.122, for a 50 amp circuit defined by a circuit being fed from a 50 amp breaker then a #10 is allowed for the EGC as per table 250.122
 
It is in a wet location so I used 3/4'' PVC schedule 40 for the raceway. That is exactly what I was looking for and I will write this down and never forget it. I appreciate the feedback and this will defiantly help me to become an Electrician. Thank You Very Much
 
roc_clmbr said:
It is in a wet location so I used 3/4'' PVC schedule 40 for the raceway. That is exactly what I was looking for and I will write this down and never forget it. I appreciate the feedback and this will defiantly help me to become an Electrician. Thank You Very Much
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Remember that is for the grounding conductor not for the grounded conductor.
 
Decreasing the size of the grounding and/or grounded conductors.

This is a big pressure washer
My guess is a Grounded, or Neutral conductor will not be used for this motor, unless there is some type of motor controll, control panel display and lighitng incorporated in the pressure washer.
If this pressure washer utilizes an adjustable speed motor drive, it may produce harmonic currents in the system Neuteral conductor, which will require you to oversize the Neutral.
I'm probably overthinking this as the motor probably does not even require a Neutral.

If you are refering to the EGC then hurk27 is correct and a #10 copper conductor is required per table 250.122

Michael H.
 
Did they tell you what type of receptacle to use (or if not, can you see what type of plug is on the pressure washer)? This will tell you whether you need a neutral or not. Usually, if you bring a neutral to a receptacle, you use the same size as the ungrounded conductors because what is planned to be plugged into a given receptacle can change over time.
 
mhanson said:
This is a big pressure washer
My guess is a Grounded, or Neutral conductor will not be used for this motor, unless there is some type of motor controll, control panel display and lighitng incorporated in the pressure washer.
If this pressure washer utilizes an adjustable speed motor drive, it may produce harmonic currents in the system Neuteral conductor, which will require you to oversize the Neutral.
I'm probably overthinking this as the motor probably does not even require a Neutral.

If you are refering to the EGC then hurk27 is correct and a #10 copper conductor is required per table 250.122

Michael H.
Click to expand...

If there is a VFD there will be harmonic current, but if the neutral is not utilized, there will not be harmonics on said neutral.

If you have a line to neutral load that produces harmonics then you have same harmonics on the line as you have on the neutral.

If you have multiple line to neutral harmonic producing loads on two or three phases, like at a service or feeder level of the system, then you start to see additive effects of the harmonics on the neutral.
 
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