plug

[jap]

A table lamp has an 18ga cord. That's typically rated for 10amps max. Yet you can plug it into a 20a circuit. That's a 50% overage just as is the 30amp cord into a 60a circuit.

What's the difference code wise because the lamp situation is perfectly within the NEC.

And let's face it. All this concern over "partial shorts". What's that anyway? The machine is said to have it's own OCPD. That will cover internal shorts and overloads. If a forklift crushes the 30a cord, the 60a breaker will still trip quite quickly.

Unless this is an AHJ issue or liability concern, I really don't see a problem here.

The difference is the NEC has nothing to do with a lamp that a customer may purchase to plug into a receptacle. so strike one.

Saying that a shorted 30a cord will quickly trip a 60 amp breaker is complete speculation. so strike two

And, changing out a factory installed male cap on a piece of equipment and plugging it into an outlet with oversized overcurrent protection will both get you into an issue with an AHJ who knows his business, and, will also throw you into assuming all liabilities of what may happen once you decide to do that.

So Strike 3,, and possibly 4 if you count the last one as 2 strikes.

JAP>

JAP>

 

[tkb]

If the SO cord terminates at an overcurent device on the machine, then isn’t the #10 SO a tap?

 

[ActionDave]

....Saying that a shorted 30a cord will quickly trip a 60 amp breaker is complete speculation. so strike two

I don't see that as speculation, that's what a breaker does. Inverse time, trip curves and all that jazz.

 

[Andy Delle]

The difference is the NEC has nothing to do with a lamp that a customer may purchase to plug into a receptacle. so strike one.

Saying that a shorted 30a cord will quickly trip a 60 amp breaker is complete speculation. so strike two

And, changing out a factory installed male cap on a piece of equipment and plugging it into an outlet with oversized overcurrent protection will both get you into an issue with an AHJ who knows his business, and, will also throw you into assuming all liabilities of what may happen once you decide to do that.

So Strike 3,, and possibly 4 if you count the last one as 2 strikes.

JAP>

JAP>

Well what does the NEC have to do with cord connected appliances or machinery either? Same argument.

So you think a dead bolted short on say 25 feet of #10 wire won't trip a 60a breaker? I'll bet it does. That's the old DIY myth that 14ga wire on a 20a breaker WILL start a fire. Now it's still a violation and I'm hardly advocating it, but a 14ga wire with 20 amps on it will get a little warm, that's about it.

When I spec professional projection rooms I always put in 5 wire 120/208Y 30a 3phase TW receptacles. The reason is the largest projectors use 30a 3p. However if a smaller unit is used that only takes 20a single phase at 208v, we just supply an adapter cord. Here too the projectors have internal OCPD. I'm not worried about a 6 foot power cord. This gives the user options.

 

[kwired]

A table lamp has an 18ga cord. That's typically rated for 10amps max. Yet you can plug it into a 20a circuit. That's a 50% overage just as is the 30amp cord into a 60a circuit.

What's the difference code wise because the lamp situation is perfectly within the NEC.

And let's face it. All this concern over "partial shorts". What's that anyway? The machine is said to have it's own OCPD. That will cover internal shorts and overloads. If a forklift crushes the 30a cord, the 60a breaker will still trip quite quickly.

Unless this is an AHJ issue or liability concern, I really don't see a problem here.

Well what does the NEC have to do with cord connected appliances or machinery either? Same argument.

So you think a dead bolted short on say 25 feet of #10 wire won't trip a 60a breaker? I'll bet it does. That's the old DIY myth that 14ga wire on a 20a breaker WILL start a fire. Now it's still a violation and I'm hardly advocating it, but a 14ga wire with 20 amps on it will get a little warm, that's about it.

When I spec professional projection rooms I always put in 5 wire 120/208Y 30a 3phase TW receptacles. The reason is the largest projectors use 30a 3p. However if a smaller unit is used that only takes 20a single phase at 208v, we just supply an adapter cord. Here too the projectors have internal OCPD. I'm not worried about a 6 foot power cord. This gives the user options.

Let's see, 20 hp 480 volt three phase motor circuit - pretty common to run 10 AWG conductor (NEC FLA is 27 amps) and put it on a 60 amp breaker. Sure hope it would trip the breaker on short circuit or ground fault.


Also have seen welders with factory installed 6-50 cord cap and only 12 AWG conductors in the cord.

 

[tortuga]

400.2 addresses flexible cords

400.2 addresses flexible cords

So far I haven't gotten an answer for the following question....

Can you put a 60a plug on SO cord rated for 30a, plug it into a 60a receptacle, if the machinery being supplied by the cord has fusing limiting the amp draw to 30a (or less)

I thought this was not acceptable but can't locate anything covering this in the code

Thanks, bob:blink:

[2017 NEC]
Your talking about 240.21. However 400.2 addresses flexible cords and states other articles of the NEC only apply as applicable and 240.21 does not apply.
What does apply then? 400.16 "Overcurrent Protection" sends us to 240.5 for overcurrent protection.

Now if your 10AWG class D stranding SJOW cord(or other 400.6 cord type) terminates on a 75-105C rated connector listed for that stranding and a 30A fuse or breaker, then we have a 60A cord cap on 30A flexible cord to 30A fused disconnect meeting NEC 400.16, 240.5(A) and NFPA 79 chapter 5. Your NEC section that allows this is 400.16-> 240.5(A). Note the 'branch circuit' ends at the receptacle as Action Dave pointed out ( See NEC art 100 def of branch circuit ) . So the #6AWG wire from a 60A breaker to a 60A receptacle then 240.10 is met. Supplementary over current protection is allowed for cords.
See NFPA 79 chapter 5

Also have seen welders with factory installed 6-50 cord cap and only 12 AWG conductors in the cord.

Welders and HID lighting are the only exceptions to 210.21(B)(3).
So for example you can install a 15A 240V receptacle on a 50A 240V branch circuit to plug in welders or HID lighting. This is because the UL product standards dictate supplemtary overcurrent protections in the welder or HID ballast.
Its kind of a chicken and egg thing with the NEC and listed products. When you take a product to UL for listing or a UL 508A panel shop they will look under parts of the NEC that say 'Construction Specifications'. So the NEC really does drive the design of many products.
Cheers

 

[kwired]

[2017 NEC]



Welders and HID lighting are the only exceptions to 210.21(B)(3).
So for example you can install a 15A 240V receptacle on a 50A 240V branch circuit to plug in welders or HID lighting. This is because the UL product standards dictate supplemtary overcurrent protections in the welder or HID ballast.
Its kind of a chicken and egg thing with the NEC and listed products. When you take a product to UL for listing or a UL 508A panel shop they will look under parts of the NEC that say 'Construction Specifications'. So the NEC really does drive the design of many products.
Cheers

That section is about receptacle rating though, does not address conductor size such as whether or not you can put a 12 AWG conductor on a 50 amp cord cap.

 

[jap]

I don't see that as speculation, that's what a breaker does. Inverse time, trip curves and all that jazz.

He said "quickly".

That's not always the case.

JAP>

 

[jap]

Well what does the NEC have to do with cord connected appliances or machinery either? Same argument.

So you think a dead bolted short on say 25 feet of #10 wire won't trip a 60a breaker? I'll bet it does. That's the old DIY myth that 14ga wire on a 20a breaker WILL start a fire. Now it's still a violation and I'm hardly advocating it, but a 14ga wire with 20 amps on it will get a little warm, that's about it.

When I spec professional projection rooms I always put in 5 wire 120/208Y 30a 3phase TW receptacles. The reason is the largest projectors use 30a 3p. However if a smaller unit is used that only takes 20a single phase at 208v, we just supply an adapter cord. Here too the projectors have internal OCPD. I'm not worried about a 6 foot power cord. This gives the user options.

I didn't say it wouldn't trip, but, I wouldn't venture to say "Quickly" every time.

Never said anything about starting a fire either.

As far as installing a smaller unit requiring 20amps at 208v and advocating putting a 20amp cord plugged into a 30 amp receptacle, I guess, to each his own.

JAP>

 

[jap]

Let's see, 20 hp 480 volt three phase motor circuit - pretty common to run 10 AWG conductor (NEC FLA is 27 amps) and put it on a 60 amp breaker. Sure hope it would trip the breaker on short circuit or ground fault.


Also have seen welders with factory installed 6-50 cord cap and only 12 AWG conductors in the cord.

Sure, but, That's rules that apply to field wiring to motors and cords attached to a piece of equipment, not changing out the factory cord cap on a machine from a 30 amp to a 60 amp just so you can plug it into an existing 60 amp receptacle.

JAP>

 

[jap]

Well what does the NEC have to do with cord connected appliances or machinery either? Same argument.

So you think a dead bolted short on say 25 feet of #10 wire won't trip a 60a breaker? I'll bet it does. That's the old DIY myth that 14ga wire on a 20a breaker WILL start a fire. Now it's still a violation and I'm hardly advocating it, but a 14ga wire with 20 amps on it will get a little warm, that's about it.

When I spec professional projection rooms I always put in 5 wire 120/208Y 30a 3phase TW receptacles. The reason is the largest projectors use 30a 3p. However if a smaller unit is used that only takes 20a single phase at 208v, we just supply an adapter cord. Here too the projectors have internal OCPD. I'm not worried about a 6 foot power cord. This gives the user options.

So you don't advocate putting 14 ga wire on a 20a breaker but you do spec professional jobs with adapters to install 12ga wire on a 30 amp breaker?

Seems like a contradiction in terms to me.

JAP>

 

[Andy Delle]

So you don't advocate putting 14 ga wire on a 20a breaker but you do spec professional jobs with adapters to install 12ga wire on a 30 amp breaker?

Seems like a contradiction in terms to me.

JAP>

Again we plug table lamps and countless other appliances into 20a circuits with 18ga cords. What's the difference? Oh, there is a difference counter to the argument. In a household, it is assumed the user has little to no electrical safety knowledge. In my application here as well as the OP's, these are commercial environments where the users do have some technical knowledge and concept of electrical safety. So in essence, the consumer example is even more dangerous yet this is done without any official concern.

We spec a 30amp 120/208Y TW receptacle. Some brands, Christie for example use full 120/208y @ 30a. Barco though uses 208/240v 20a single phase (or two phases of a 120/208y). So yes, it has a 12ga cord with a L6-20R. We use an adaptor to plug that into the 30a 120/208y. There is no safety hazard here. The projectors have their own OCPD. Then we see NEC units that are also 208/240v 20a 1ph but with an L6-20(non twistlock). The idea here is one receptacle can be used with any commercial projector on the market.

Is it NEC compliant? Yes it is IMO and has always passed inspections. The reason is the NEC stops at the wall. Cord connected appliances are outside the NEC. Now the AHJ may look for UL listing on major equipment (and they do in Los Angeles) but that's another issue outside of the NEC.

 

[jap]

Again we plug table lamps and countless other appliances into 20a circuits with 18ga cords. What's the difference? Oh, there is a difference counter to the argument. In a household, it is assumed the user has little to no electrical safety knowledge. In my application here as well as the OP's, these are commercial environments where the users do have some technical knowledge and concept of electrical safety. So in essence, the consumer example is even more dangerous yet this is done without any official concern.

We spec a 30amp 120/208Y TW receptacle. Some brands, Christie for example use full 120/208y @ 30a. Barco though uses 208/240v 20a single phase (or two phases of a 120/208y). So yes, it has a 12ga cord with a L6-20R. We use an adaptor to plug that into the 30a 120/208y. There is no safety hazard here. The projectors have their own OCPD. Then we see NEC units that are also 208/240v 20a 1ph but with an L6-20(non twistlock). The idea here is one receptacle can be used with any commercial projector on the market.

Is it NEC compliant? Yes it is IMO and has always passed inspections. The reason is the NEC stops at the wall. Cord connected appliances are outside the NEC. Now the AHJ may look for UL listing on major equipment (and they do in Los Angeles) but that's another issue outside of the NEC.

The difference is in where the "so called electrician" goes changing out factory installed cord ends with his grubby little hands to match whatever happens to be there that he needs to plug into.

Your correct, in a household most have little or no electrical safety knowledge, yet they don't go cutting the factory ends off of their lamps, or, blatently installing 12 guage adapters into 30 amp receptacles.

They let some of the fine folks who claim they are electricians with the vast amount of knowledge do those code violations for them.

JAP>

 

[Andy Delle]

The difference is in where the "so called electrician" goes changing out factory installed cord ends with his grubby little hands to match whatever happens to be there that he needs to plug into.

Your correct, in a household most have little or no electrical safety knowledge, yet they don't go cutting the factory ends off of their lamps, or, blatently installing 12 guage adapters into 30 amp receptacles.

They let some of the fine folks who claim they are electricians with the vast amount of knowledge do those code violations for them.

JAP>

You are looking at this from what you think is the NEC. Again the NEC does not have jurisdiction over cord connected devices. UL and other listing services do but they still openly allow an 18ga cord where they know full well this can be attached to a 20a circuit - a 100% over current condition for 18ga wire.

Now looking at this as an EE, it's simple to see here there is no inherent safety issue. The cord cannot be overloaded as the device in my case has OCPD - note the table lamp does not btw. And any shorting of the cord will still trip a 30a breaker.

Show me the safety issue?

 

[jap]

You are looking at this from what you think is the NEC. Again the NEC does not have jurisdiction over cord connected devices. UL and other listing services do but they still openly allow an 18ga cord where they know full well this can be attached to a 20a circuit - a 100% over current condition for 18ga wire.

Now looking at this as an EE, it's simple to see here there is no inherent safety issue. The cord cannot be overloaded as the device in my case has OCPD - note the table lamp does not btw. And any shorting of the cord will still trip a 30a breaker.

Show me the safety issue?

Forget all of this stuff that's getting way of base and go back and read Post #1.

Then, from an NEC perspective, since this is what this forum is all about, let me know what your answer would be.

JAP>

 

[kwired]

Forget all of this stuff that's getting way of base and go back and read Post #1.

Then, from an NEC perspective, since this is what this forum is all about, let me know what your answer would be.

JAP>

My answer is NEC doesn't specifically prohibit anything like OP is asking that I am aware of.

If equipment in question is listed and specifies 30 amp OCPD in the listing/instructions, then 110.3(B) is the section to cite.

Since OP's equipment has overcurrent protection within the unit - the cord is essentially a feeder tap - is there anything that would prohibit that?

 

[Andy Delle]

Forget all of this stuff that's getting way of base and go back and read Post #1.

Then, from an NEC perspective, since this is what this forum is all about, let me know what your answer would be.

JAP>

I don't see this as an NEC issue. The NEC jurisdiction stops at the wall outlet.

 

[jap]

I don't see this as an NEC issue. The NEC jurisdiction stops at the wall outlet.

This should have been Post #2.


JAP>

 

[retirede]

This should have been Post #2.


JAP>

It was mentioned in post 15.

 

[jap]

It was mentioned in post 15.

Yes it was, but, the installing electrician work does not always stop at the receptacle.

If a person in a plant came up to me and asked me the question in post #1, I would say, "No I wont change that male cap out, but, I will install you a receptacle outlet that you can plug it into that matches it's configuration.


JAP>