Gauge of wire for Ground

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swamper8

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Good afternoon folks,
I work in an engineering lab. I cam currently working on a project that brings in a 110VAC power cord into a simulator. This cord plugs into a receptacle (plastic) which isolates it from the metal chassis of the simulator. From the receptacle, I have run a Green/Yellow 18 gauge wire from the receptacle ground terminal to the metal chassis of the simulator.
My supervisor posed the question that he believes the NEC states that the gauge of the wire traveling from the receptacle to the chassis must be 1 gauge larger than that which is carrying the voltage from the wall.

So, basically, the cord that I plug into the simulator has three 18AWG stranded wires inside. According to him, I must use at least a 16AWG stranded wire from my receptacle to my chassis ground stud.

Can anyone comment on if this is true? Can I use a 18AWG to the ground stud just as the cord has a 18AWG coming in? Or do I need to go one bigger? I would appreciate a reference to the NEC as to what the standard is. That way I can print that particular bit of code out and bring it to him as proof.
thank you
 
swamper8 said:
Good afternoon folks,
I work in an engineering lab. I cam currently working on a project that brings in a 110VAC power cord into a simulator. This cord plugs into a receptacle (plastic) which isolates it from the metal chassis of the simulator. From the receptacle, I have run a Green/Yellow 18 gauge wire from the receptacle ground terminal to the metal chassis of the simulator.
My supervisor posed the question that he believes the NEC states that the gauge of the wire traveling from the receptacle to the chassis must be 1 gauge larger than that which is carrying the voltage from the wall.

So, basically, the cord that I plug into the simulator has three 18AWG stranded wires inside. According to him, I must use at least a 16AWG stranded wire from my receptacle to my chassis ground stud.

Can anyone comment on if this is true? Can I use a 18AWG to the ground stud just as the cord has a 18AWG coming in? Or do I need to go one bigger? I would appreciate a reference to the NEC as to what the standard is. That way I can print that particular bit of code out and bring it to him as proof.
thank you
Click to expand...

Ask him for a code reference. In general the EGC is not required to be larger than the circuit conductors.

Welcome to the Forum. :).
 
1) is the simulator a listed assembly ?
2) curious, why didn't you provide a grounded cord assembly ?
3) article 250 (looking for the code section) might apply, but if the simulator is a listed assembly, then the listing might apply. if the simulator isn't listed, I'm not sure if it should be plugged in (I'm sure someone else will have something to say about that)
 
(see 250.114 to start with), and note 250.4 A that applies. 250.122 A might apply to the size 250.138 applies to the method you used to attach (which seems to comply)
 
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How about 250.122(E): Flexible Cord and Fixture Wire. The equipment grounding conductor in a flexible cord with the largest circuit conductor 10 AWG or smaller, and the equipment grounding conductor used with fixture wires of any size in accordance with 240.5, shall not be smaller than 18 AWG copper and shall not be smaller than the circuit conductors. The equipment grounding conductor in a flexible cord with a circuit conductor larger than 10 AWG shall be sized in accordance with Table 250.122.
 
Thank you for the code references everyone. To answer some of the questions:

1.) I'm not sure what "listed" means. I work in an engineering lab so much of what we build are "one-offs" of which most people don't even know what they do. They are for in house use only.

2.) The cord is a grounded cord assembly. But the cord plugs into a plastic receptacle, so on the other side of the receptacle I had to put in a wire to run from the ground terminal to the chassis of the simulator.

3.) My boss didn't have a code reference, he left it up to me to investigate!

I am going to go pour over these code references that have been provided.
Thank you
 
swamper8 said:
2.) The cord is a grounded cord assembly. But the cord plugs into a plastic receptacle, so on the other side of the receptacle I had to put in a wire to run from the ground terminal to the chassis of the simulator.
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Would this 'receptacle' actually be a power inlet, with male pins on the chassis part and female slots on the cord end (I hope)?

There's nothing in the NEC in regards to your project, but there's no electrical reason for a jumper larger than the other wires.

You're certainly permitted to use a larger grounding jumper if you, the designer, or the end user prefers. Who's paying the bills?
 
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