See, I do occasionally know what I am talking about.
Making extension cords and quad boxes
- Thread starterDaveslights
- Start date
Ship,
I cannot think of any portion of any electrical code I've ever read that allows this. Note my phrasing, as I make no claims to be expert on the US National Electrical Code.
I am assuming that the scenario you are describing indicates that the 20 amp circuit is protected by a 20 amp overcurrent device, and that all (other) electrical devices connected to this 20 amp fuse/breaker are rated at 20 amps, except for the 15 amp connector.
This 15 amp connector now becomes the weakest link in the circuit, defeating the intent of the overcurrent protection. That is certainly not allowed by code.
I am currently racking my brain to remember where this recently came up, all related to power strips, number of connections downstream, etc...
Steve B.
Here's the article from LEX's website about the redesign of their E-string product.
We got the change that prohibits the receptacles from facing up. However the one we missed is if the cord has 4 or more receptacles, the male plug at the beginning of the cord can't be NEMA 5-15, It has to be NEMA 5-20 now.
We got the change that prohibits the receptacles from facing up. However the one we missed is if the cord has 4 or more receptacles, the male plug at the beginning of the cord can't be NEMA 5-15, It has to be NEMA 5-20 now.
JD
Well-Known Member
The only real solution to this whole mess is to make it up out of 12/3, but label the whole darn thing 15 amps!
It's all kind of a catch-22 based on the angle of the plug blade. I once thought I was wise and made up a bunch with the (male) right angle blades- Ended up cutting them all off after about a month! For a traveling show, you end up condemning yourself to a standard that is not too standard! We'd set up follow spots, be shown the "20 amp plugs" in the theater, and sure enough they would be straight blade! Now, you could sit there and argue with every venue owner about it, and be right... But you wouldn't get invited back much
JD
Well-Known Member
Hee hee! The first generation of Crown Microtec (spelling?) power amps all came through with the angle blade as they had a 20 amp draw. Packed in with the amp was the 5-20 to 5-15 adapter! I always found that funny! It's like their saying- "Hey, we want to do things right here but we know you all live in the real world."
It's "male end first" because we are a patriarchal society and stage work is/was dominated by male chauvinist pigs and that's what was decided by the Broadway Lighting Shops many years ago, and, since it appears in just about every textbook on stage lighting (usually in the "shop order" section), it's the law. /rant off.
Oh...................
I liked my version better.
Reminds me of the story of the plumber who sold ball valves for $5 and butterfly valves for $30. People will pay more for the "nice" term.
I liked my version better.
Reminds me of the story of the plumber who sold ball valves for $5 and butterfly valves for $30. People will pay more for the "nice" term.
Thats what has never made sense to me about this code, it's perfectly OK to plug a 16 gauge, 10 amp cable into a 20 amp receptacle. However the plugs are designed to stop you from plugging a safer 20 amp cable into a 15 amp outlet? In case A you stand a considerable chance of accidentally overloading a 16 (or less!) gauge cable if you don't know what you are doing. In case B, well, you might blow a breaker if you happen to have a single device that is actually fully 20 amps, but, it's far more likely the outlet would get overloaded in other ways.
I'm noting on the LEX products E-String change news item that it was UL that recommended the change to their E-Strings, not persay compliance with the NEC where a few members of the company if I remember correctly sit on the board.
Of the NEC 2002 Handbook version of the code (sorry didn't buy the latest version)
Granted article 406.7 Noninterhangeability is what supports your argument for general purpose correctness, there is an exception to it that I remember for stage usage that was clarified later publically if not in later code books.
Article 520.9 notes says
“The stage set lighting and associated equipment, such as stage effects, both fixed and portable, must be as flexible as possible. Connectors are often used for different purposes and are therefore marked on a show-by-show basis as to the voltage, current and type of current actually employed. The provisions of 520.9 only require that connectors be rated sufficiently for the parameters involved, thus permitting connectors with voltage and current ratings higher than the branch-circuit rating to be used. ...”
This is not the article I was thinking of but is similar in showing for production usage there are some exceptions written in for use of plugs in situations other than the plug's spec.
Still this is not the Edison exception I was looking for. I do very specifically remember reading either in a proposed or change to the NEC specific to the article 520 area, or clarification if not even IESTA tech brief on the subject that 15a Edison plugs of commercial grade (the only type of plug allowed for use on stage - another rule I remember but don't see easily found) are acceptable in place of a 20a one. I do remember this being a clarified acceptable alternative to using 20a plugs. Granted I also cannot find the article/paper.
Lex Product's change is a safety thing in I would assume making the cable assembly safer for use by non-qualified personel - band teachers etc. and sensible for a general product as would using a 20A plug for a 20A load as a general concept. I can understand why UL would request the change but also note a lack of NEC requirement to do this stated in the article and it would be were it the rational and or requirement. http://www.lexproducts.com/technical/estring_redesign.aspx
But as stated above - frequently such 20A plugs confuse stage hands even where there is a 20a outlet available for use. Granted this confusion would go against the concept of "qualified personel" using the equipment that is the base of exception, as with commercial/industrial grade plugs where it is the exact same plug just different pin configuration also assumed to be in use which is in use by the "qualified personel". Lack of professional "qualified personel" oprating equipment never ceases to amaze me and I'll leave it at that.
Have to leave this question at a draw until either of us stumble upon the exception that on my word was specifically mentioned in the NEC at one point recently if not is the current rule.
This and also a NEC rule I didn't see in a quick search but know is also there that on a 20A branch circuit with more than one outlet it is permissible to use 15a outlets for those multiple outlets.
ship;77939This and also a [autolink said:
I too was curious as to why it was UL that asked for the change in the LEX designs, especially the left/right outlet design versus on top, when that seemingly would be a NEC issue. UL usually just tests for fire rating and such, where as this almost seems an issue for OSHA and NEC, in terms of how a product is used.
As to 15 vs, 20, when you think about, and as comment to another post about 16 gauge wires, the NEC (as well as UL for that matter) essentially allows 16 and 18 gauge zip cords, as well as devices whose cables are not rated at the load protection.
The key is the DEVICE is the end user and the wiring need not be the same rating as a circuits over-current protection, and doesn't need to be, as the presumption is that the device load is not greater then the supplied cabling and plug. That's a UL issue.
That is not the same as extension cords, where you cannot (or should not) use connectors and cabling rated lower then the over-current protection and where the devices downstream may well pull a load greater then the capacity of the extension cord.
I have the 2005 NEC book at work and will see if I can find what you're refering too. Could be you are correct, though it goes against everything I've ever learned about electrical safety to prevent the connectors and cabling being a fused link in a circuit.
Steve B.
JD
Well-Known Member
Which begs the question, why can a homeowner walk into home depot and buy a 16/3 (or 18/2) extension cord ???
I have never for the life of me understood why this is the case! How many times do you hear about house fires that were caused by heaters being plugged into under gauge extension cords? Look at those 18/2 zip cord extension cords, and they have a UL label on them! This would give the user the false impression that it is safe. (Of course if you bother read the fine print there is a load limit.)
I think this is a case where something is so popular that no one even tries to regulate it. I know, if you are extending a table light, it would seam stupid to run a chunk of 12/3, yet, that is actually what the "device" rules would imply, as the extension cord is not the "device."
I had to chuckle on my last trip to Disney World. They have all these 22 gauge Christmas light sets plugged into 12/3 feeders!
Early on, (think 35 years ago) I had an electrician tell me that anything past the outlet is considered "temporary" and the rules don't apply. I am sure glad that is not the case in the theater environment! And we won't even talk about the "self electrocution chair" called the Edison light bulb base found in those table lamps! (Rant covered elsewhere.) One thing is for sure, in the home, "temporary" wiring can be equated to the wild wild west!
I have never for the life of me understood why this is the case! How many times do you hear about house fires that were caused by heaters being plugged into under gauge extension cords? Look at those 18/2 zip cord extension cords, and they have a UL label on them! This would give the user the false impression that it is safe. (Of course if you bother read the fine print there is a load limit.)
I think this is a case where something is so popular that no one even tries to regulate it. I know, if you are extending a table light, it would seam stupid to run a chunk of 12/3, yet, that is actually what the "device" rules would imply, as the extension cord is not the "device."
I had to chuckle on my last trip to Disney World. They have all these 22 gauge Christmas light sets plugged into 12/3 feeders!
Early on, (think 35 years ago) I had an electrician tell me that anything past the outlet is considered "temporary" and the rules don't apply. I am sure glad that is not the case in the theater environment! And we won't even talk about the "self electrocution chair" called the Edison light bulb base found in those table lamps! (Rant covered elsewhere.) One thing is for sure, in the home, "temporary" wiring can be equated to the wild wild west!
On a recent trip into HD, I picked up a short (2ft.) extension made out of 12/3, terminating in a 3 way tap. Granted it's only rated at 15 amps, as per the pin config. of the male connector, but my observations were that HD is now carrying a lot more extension cords in heavy gauge cabling then I remember. They had a few 16 ga. zip extensions, but some 14 ga. zip with grounded male and grounded 3 way female, as well.
So maybe that's a trend, away from the non-grounded 18 and 16 ga., 5 and 10 amp, non-grounded crap, towards stuff that actually won't burn your house down. And maybe the big box companies don't want the liability issues.
Steve B.
STEVETERRY
Well-Known Member
I think you might be referring to a part of 520.67 Multipole Branch Circuit Cable Connectors:
.......The connector shall be rated in amperes and designed so that differently rated connectors cannot be connected together; however a 20-ampere T-slot receptacle shall be permitted to accept a 15-ampere attachment plug of the same voltage rating...............
That is not the same thing as 15A outlets on a 20A branch circuit.
However, Section 210.21(B)(3) and Table 210.21(B)(3) do allow either 15A or 20A outlets on 20A branch circuits with two or more outlets.
ST
Last edited:
Hmm... That took me a while to read and I'm not sure I've properly digested it. I'm going to add some thoughts from down here, your rules and my rules aren't the same, we all know that, so as always, check your rules before you start wiring things up.
Any device having multiple outlets connected through to a single plug MUST have a circuit breaker, rated to the total capacity of the device, so if it has a 10A plugtop and cable, then your breaker should also be 10A. Now bear in mind that 10A is the normal everyday socket around here, but if you have a device fed by say a 15 or 20A plug, you can have a 15 or 20A socket on it, but you can only have one such outlet, any other outlet may only be 10A.
Our plugs and sockets are designed such that you can plug a 10A plug into a 10, 15 or 20 A socket, a 15A plug into a 15 or 20A socket and a 20A plug into a 20A socket. And I have no problem with that. The plug and cable need only to be rated at the current draw of the appliance, while the breaker is there in reality to protect the wiring installed in the walls which, if it were to catch fire, would be much harder to control than a piece of flex.
In building wiring, I think the rules are that you can have up to 8 GPOs on a 20A breaker or 1 15A outlet or 1 20A outlet. But of course for certain high current appliances or for other reasons, you may want things on their own breakers. Nothing to stop the use of a 10A or even down to I think 1A breaker if that's all a circuit needs - control circuits would be the main users of such small breakers.
Oh and one cannot legally have a cable down here that has a plug and socket of different current ratings. If the socket is of lower rating than the plug then it would be perfectly safe, but it was just easier to write a blanket rule...
And to be honest, the original post was starting to trigger the if you have to ask you shouldn't be doing it alarm...
Food for thought...
Any device having multiple outlets connected through to a single plug MUST have a circuit breaker, rated to the total capacity of the device, so if it has a 10A plugtop and cable, then your breaker should also be 10A. Now bear in mind that 10A is the normal everyday socket around here, but if you have a device fed by say a 15 or 20A plug, you can have a 15 or 20A socket on it, but you can only have one such outlet, any other outlet may only be 10A.
Our plugs and sockets are designed such that you can plug a 10A plug into a 10, 15 or 20 A socket, a 15A plug into a 15 or 20A socket and a 20A plug into a 20A socket. And I have no problem with that. The plug and cable need only to be rated at the current draw of the appliance, while the breaker is there in reality to protect the wiring installed in the walls which, if it were to catch fire, would be much harder to control than a piece of flex.
In building wiring, I think the rules are that you can have up to 8 GPOs on a 20A breaker or 1 15A outlet or 1 20A outlet. But of course for certain high current appliances or for other reasons, you may want things on their own breakers. Nothing to stop the use of a 10A or even down to I think 1A breaker if that's all a circuit needs - control circuits would be the main users of such small breakers.
Oh and one cannot legally have a cable down here that has a plug and socket of different current ratings. If the socket is of lower rating than the plug then it would be perfectly safe, but it was just easier to write a blanket rule...
And to be honest, the original post was starting to trigger the if you have to ask you shouldn't be doing it alarm...
Food for thought...
Similar threads
