I have a welder with a 3 prong plug and I thought I could use my dryer line which is 4 wire (red ,black,white &ground)i bought a female 3prong receptacle to match welder plug.but I can't figure where to attach white and ground do I leave one out?or am I doomed from the start .thanks for any help.

Are you trying to permanently install a receptacle for the welder or are you trying to make an extension (adapter) cord to be plugged into the existing dryer receptacle.

What in the input voltage and amperage of the welder? What is the duty cycle of the welder?

Okay, first and most important of all, it is a violation of code to extend the dryer outlet to another receptacle, period!

The dryer is a dedicated circuit.
Don, this is just not so.

If there is more than one receptacle on a circuit like this you are limited to 80% of the circuit for any one plugged-in load.
So as long as a dryer or welder does not draw more than 24A you can have 500 receptacles on this circuit if you want.

Stan,

I removed my response based upon your reply.

I'll go digging in the code book to see if it is there or in my class notes to see if this was given as part of the class.

Thanks for the help.

Check out 210.23 & 210.24

Will do!

While Don continues with Code lessons, perhaps I will answer the question.

The welder will only need the two hot conductors and one equipment ground, either bare or green conductor, will not need the white neutral.

Don, not every real life situation will be found listed in the Code, hardly any in fact can be found. It is an electricians responsibility to know the text of the Code, and when to apply it.

The Code can be a friend when understood completely.

With respect to my deleted answer.

The answer I gave was based on class notes, not code. My error.

According to my notes, the instructor stated that it was prohibited because of design considerations (paraphrased)

Don, remember, instructor are not always right. Many will inject their own personal opinions. Inspectors can be the same way sometimes. That is why if you get called on something you call them right back and ask for a code reference.

He might have been saying that some instructions of dryers call for their use on an individual circuit. In such a case it would be a technical NEC violation of the unit's listing. It would not be an NEC wiring violation.

Stan - TK,

Okay, I still get hung on 210.23 rather than 210.23(B).

210.23 prohibits the connected load from exceeding the BC ampere rating.

210.23(B) says that you are allowed multiple receptacles, however, no single piece of equipment can exceed 80% of the BC ampere rating. In this case, 24 Amps.

As I apply 210.23(B), I can have two 10 amp pieces of equipment because neither device exceeds 24 amp, correct?

I could also have a 23 amp device and another 6 amp device because I have not violated 210.23(B)

I cannot have a 20 amp and a 15 amp (35 amp) connected load because they would exceed the 30 amp rating of the circuit, 210.23 yet the loads would be matematically allowed by 210.23(B)-correct?

What am I mis-applying?

Stan - TK

I have sent the following question to the NEC for clarification.

The question has been assigned to the engineering group today, we can expect the answer within 5 working days.

"Greetings,

I need clarification on two sections of Article 210.23, please.

I have a customer that would like me to extend the Dryer BC (30 amp) across the garage to another 30 amp receptacle that will service a welding machine.

My position is that article 210.23 is the governing article. This article states that I cannot have a connected load greater than the BC rating. In this situation, two 30 amp pieces of equipment would equal a 60 amp load if both devices were in use at the same time.

The GC responded that 210.23(B) allows for multiple receptacles as long as no single load was greater than 24 amps.

My response is that 210.23 supersedes 210.23(B) and that 210.23(B) is actually limiting the maximum allowable load of multiple receptacles connected devices to 24 amps. Not one device that is 24 amps and one device that is 6 amps.

As I interpret 210.23, it is telling me that I can have up to 30 amps on a 30 amp circuit.

210.23(B) is telling me that I can have as many 30 amp receptacles as I want, but that I cannot have a connected load greater that 24 amps.

For example: according to 210.23(B), I can have one load at 18 amp and one load at 6 amp. What I cannot have is one load at 22 amp and one load at 8 amp.

Am I miss interpreting this article of code?

Re-reading this post from the beginning, I see it instantly went off topic when you assumed the request was to ADD an outlet to the circuit, and Stan comes back with more outlets can be added to an existing circuit. Then I come along and fall into the same hole created by an incorrect assumption.

All that Kmarquis asked was how to connect the welder's 3 wire cord to a NEW 4 wire male plug so he/she could use the EXISTING dryer receptacle for his/her welder.

I will let you, Stan, and the NEC hash out the debate on adding outlets to a dryer circuit. I have my own opinion and editorial, but it is off the original topic.

Understood, thanks TK.

T.K. - Stan,

Would it be fair to say that I am merging "Circuit design" with code?

Good catch on the direction of this thread TK. It did go bad rather quickly. :o

Don, Yes, good way of putting it:


T.K. - Stan,

Would it be fair to say that I am merging "Circuit design" with code?

Response from NEC:

1. Section 210.23 applies in all cases and requires that the single utilization equipment load or the combined utilization equipment load not exceed the rating of the branch circuit.

2. Section 210.23(B) limits the load of any one cord-and-plug-connected utilization equipment to 24 amperes where multiple loads are supplied.

3. Section 210.23(B) does not limit the combined cord-and-plug-connected or permanently connected utilization equipment load to 24 amperes. The main requirement of 210.23 covering the total load on the branch circuit is applicable.

4. The circuit sizing and overcurrent protection requirements for electric welders are covered in Article 630.

OK, all they did was quoted Code sections.

What is the conclusion?

TK,

I highlighted what I believe to be the salient points of interest for me in the response above.

210.23 - Governs 210.23(B).

Also, 210.23(B) allows for multiple utilization equipment receptacles and that any one piece of equipment cannot exceed 24 Amp. However, the prohibition of not exceeding the 30 amp circuit applies.

It would be allowed to have 2 devices one 24 amp and one 6 amp.

It would not be permissible to have one device at 20 amp and another at 15 amp.

Even though this was the incorrect path to take with this question, it became a good learning exercise.

Fun huh?

If someone at a home wanted to use a dryer circuit for something like a welder,I woild not have a problem with it, as long as the owner clearly understood both could not be used at the same time.

The intent of the Code is when an installer is done wiring a building, it is left "Idiot proof" so to speak, and the end user can use the electricla system and all will work safely.