15 Amp Plug on 20 Amp Outlet

[STEVETERRY]

Hijacking this post a little... but with the world famous @STEVETERRY present I'm curious now.

Ran across a rennovation recently that had l5-15 recepticles connected to a patchbay with GPC connectors designed to patch into 20-amp circuits. Leaving aside, for a second, the unfortunate choice of L5-15 as a connector--Is this legally allowed? Are the recepticles rated for 15 amps allowed given that they, theoritecally, limit anything being connected to them draw a maximum of 15 amps of current? Or given that the OCPD protecting this patch is rated for 20 amps, should the recepticle in question also be required to be an L5-20?

This is not simple.

A typical patch panel with the male plugs connecting to building wiring will need supplementary overcurrent protection on each of the male tails. That is to prevent the male plugs being fed from a branch circuit with a larger OCPD than the rating of the circuits they feed. So, in the case you describe, the female receptacles would have 20A OCPD, but the male plugs would have additional 15A OCPD.

Are the male tails indeed feeding permanent in-wall circuits?

ST

 

[danTt]

This is not simple.

A typical patch panel with the male plugs connecting to building wiring will need supplementary overcurrent protection on each of the male tails. That is to prevent the male plugs being fed from a branch circuit with a larger OCPD than the rating of the circuits they feed. So, in the case you describe, the female receptacles would have 20A OCPD, but the male plugs would have additional 15A OCPD.

Are the male tails indeed feeding permanent in-wall circuits?

ST

The male tails are feeding a permanent raceway. To the best of my knowledge there is not a supplemental 15amp OCPD on the male tails. The male and female connectors at the patch bay are 20amp GPC connectors, and all cable run from patch bay to receptacle is 12 gauge. The only "weak point" in this is the L5-15R at the end. I'm thinking it's one of those technically incorrect situations, but probably not unsafe enough to fight about.

If using listed 20amp connectors at both the female patchbay receptacle, the male patchbay connector, and the final female receptacle with a 20amp OCPD on the feed at the patchbay, is an additional OCPD still required? It would feel like the 20amp connectors would already do this limiting, but I haven't dug too deeply into the NEC regarding this...

Thanks,

 

[BillConnerFASTC]

You have to protect the wiring in the building. You cannot guarantee whatever you are pluggin into will now and for the life of building have the correctc or lower ocpd forever. You could plug that pigtail into a 50 amp device for instance.

Look for intercept panel in NEC iirc.

 

[danTt]

You have to protect the wiring in the building. You cannot guarantee whatever you are pluggin into will now and for the life of building have the correctc or lower ocpd forever. You could plug that pigtail into a 50 amp device for instance.

Look for intercept panel in NEC iirc.

I'd argue that a world in which an electrician decided to break code and install a 50amp breaker feeding a receptacle rated for twenty amps will be a world that supports enough other bad ideas that the transfer panel won't save the building, yes?

More to the point, in this world the electrician could just as easily replace the 20amp breaker on the transfer panel with a 50amp, and the extra expense on infrastructure would suddenly be irrelevant.

Tl;Dr: you can't fix stupid?

 

[derekleffew]

Look for intercept panel in NEC iirc.

Look for Road Show Connection Panel. NEC 520.50.
.

 

[STEVETERRY]

I'd argue that a world in which an electrician decided to break code and install a 50amp breaker feeding a receptacle rated for twenty amps will be a world that supports enough other bad ideas that the transfer panel won't save the building, yes?

More to the point, in this world the electrician could just as easily replace the 20amp breaker on the transfer panel with a 50amp, and the extra expense on infrastructure would suddenly be irrelevant.

Tl;Dr: you can't fix stupid?

So, imagine we're in a theatre with this panel shooting an award show. The director says " I just need one more 2K fresnel over here, for a short shot." There is only one circuit feeding that location, and it's fed by our unprotected circuit. We have a spare 6kW dimmer, and the gaffer succumbs to the pressure and plugs the male connector into a 50A circuit. Sound far fetched? Not so much. That's why we have NEC 520.50.

520.50 Road Show Connection Panel (A Type of Patch Panel).
A panel designed to allow for road show connection of portable
stage switchboards to fixed lighting outlets by means of
permanently installed supplementary circuits. The panel,
supplementary circuits, and outlets shall comply with
520.50(A) through (D).

(A) Load Circuits. Circuits shall originate from grounding type
polarized inlets of current and voltage rating that match
the fixed-load receptacle.

(B) Circuit Transfer. Circuits that are transferred between
fixed and portable switchboards shall have all circuit conductors
transferred simultaneously.

(C) Overcurrent Protection. The supply devices of these
supplementary circuits shall be protected by branch-circuit
overcurrent protective devices. Each supplementary circuit,
within the road show connection panel and theater, shall be
protected by branch-circuit overcurrent protective devices
installed within the road show connection panel.

(D) Enclosure. Panel construction shall be in accordance with
Article 408.

ST

 

[danTt]

See

So, imagine we're in a theatre with this panel shooting an award show. The director says " I just need one more 2K fresnel over here, for a short shot." There is only one circuit feeding that location, and it's fed by our unprotected circuit. We have a spare 6kW dimmer, and the gaffer succumbs to the pressure and plugs the male connector into a 50A circuit. Sound far fetched? Not so much. That's why we have NEC 520.50.
ST

To the best of my understanding, the only way this would work is if the gaffer happened to have an adaptor in their bag with a 50amp bates plug on one end and a 20amp bates recepticle on the other. This adaptor is already illegal, correct?. Any appropriate 50amp->20amp breakout already has 20ampOCPDs built in. If the Gaffer is prepared to break code by furnishing this adaptor, where else are they prepared to break code? Should code anticipate and add additional levels of complexity for these situations?

This is an interesting conversation on it's own, but I also think we're starting to stray a bit from my initial tangent For the sake of discussion, let's say that I have a transfer panel with 20amp OCPDs, 12 gauge wire, and L5-15 receptacles feeding fixtures. Based on the first half of the thread, would this be to code?

 

[STEVETERRY]

See


To the best of my understanding, the only way this would work is if the gaffer happened to have an adaptor in their bag with a 50amp bates plug on one end and a 20amp bates recepticle on the other. This adaptor is already illegal, correct?. Any appropriate 50amp->20amp breakout already has 20ampOCPDs built in. If the Gaffer is prepared to break code by furnishing this adaptor, where else are they prepared to break code? Should code anticipate and add additional levels of complexity for these situations?

This is an interesting conversation on it's own, but I also think we're starting to stray a bit from my initial tangent For the sake of discussion, let's say that I have a transfer panel with 20amp OCPDs, 12 gauge wire, and L5-15 receptacles feeding fixtures. Based on the first half of the thread, would this be to code?

Let's have a lottery:

1. I'll give you $1.00 for every 50A to 20A adapter we can find with an integral OCPD.
2. You give me $1.00 for every 50A to 20A adapter we can find with no OCPD.
3. BTW, we're including film rental house inventories.

I'm already planning my Caribbean vacation on the proceeds.

ST

 

[BillConnerFASTC]

I'd argue that a world in which an electrician decided to break code and install a 50amp breaker feeding a receptacle rated for twenty amps will be a world that supports enough other bad ideas that the transfer panel won't save the building, yes?

More to the point, in this world the electrician could just as easily replace the 20amp breaker on the transfer panel with a 50amp, and the extra expense on infrastructure would suddenly be irrelevant.

Tl;Dr: you can't fix stupid?

It cannot be assured the portable and temporary devices that may be used to feed the circuits will always have 20 amp ocpd.

 

[RonHebbard]

It cannot be assured the portable and temporary devices that may be used to feed the circuits will always have 20 amp ocpd.

Understood but it should be more stringently / rigidly enforced.
Toodleoo!
Ron Hebbard.

 

[STEVETERRY]

Understood but it should be more stringently / rigidly enforced.
Toodleoo!
Ron Hebbard.

It is enforced--by the required addition of supplementary OCPD's on permanent circuits fed by male inlets or male tails.

We gave up on the honor code of overcurrent protection many years ago!

ST

 

[derekleffew]

So, imagine we're in a theatre with this panel shooting an award show. The director says " I just need one more 2K fresnel over here, for a short shot." There is only one circuit feeding that location, and it's fed by our unprotected circuit. We have a spare 6kW dimmer, and the gaffer succumbs to the pressure and plugs the male connector into a 50A circuit. Sound far fetched? Not so much. That's why we have NEC 520.50.

Sorry, I still don't see a problem with this, as the 2K Fresnel came from the <insert Hollywood grip shop of your choice> shop with a 5-15P male Edison PB&J plug.

 

[STEVETERRY]

Sorry, I still don't see a problem with this, as the 2K Fresnel came from the <insert Hollywood grip shop of your choice> shop with a 5-15P male Edison PB&J plug.

Ah, but it was the second 2kW Fresnel plugged into that 20A circuit connected to a 6kW dimmer.

ST

 

[lightman02]

Hello, we have some source four lekos fitted with 20 amp twistlock connectors... However we want to use them in a location with 20 Amp Edison outlets. I've always been told "if the circuit is capable of 20A, everything in the circuit need to be rated 20A or higher" but the way I'm thinking right now is that a 575w lamp in our lekos doesn't draw 20A through it's plug... So why can't I use a 15A plug, most 20A Edison plugs I've seen are $10 or more. For 16 fixtures this can be a lot. Is there a good reason for this rule I was told or is that only for the parts of the circuit which will receive 20A?

This is why I don't come to this forum much anymore. You ask a simple question and it turns into two pages of rambling posts of confusion by certain theatre gods about a very simple question. Yes, you absolutely can do it, not an issue. Make sure you get a quality UL approved connector and your done. Have a nice day and good luck!!

 

[GreyWyvern]

This is why I don't come to this forum much anymore. You ask a simple question and it turns into two pages of rambling posts of confusion by certain theatre gods about a very simple question. Yes, you absolutely can do it, not an issue. Make sure you get a quality UL approved connector and your done. Have a nice day and good luck!!

That's the reason so many people come to this forum. You ask a simple question and it turns into two pages of educational posts of teaching by certain theatre gods about a very simple question. How wonderful is that!

Side note: It's also called conversation!
If someone is just looking for a simple answer, they'll almost always find it in the first couple of replies. Great! They can stop reading there. Or... they can continue reading and likely learn something new. No one is forcing anyone to read every word of the forum.

 

[lightman02]

I don't agree, it's not so great when someone wants a simple answer to a simple question. It creates a lot of confusion is my point which you obviously don't get.

 

[RonHebbard]

I don't agree, it's not so great when someone wants a simple answer to a simple question. It creates a lot of confusion is my point which you obviously don't get.

@lightman02 Have you been told today sonny or is communication and reading beyond your social skill-set along with basic politeness "which you obviously don't get" either?
This old blind dude'll quit typing now and crawl back into my own hole as I sense the proximity of @dvsDave 's silver deletion hammer about to descend heavily upon me. How's that @GreyWyvern and @TimMc ? (Kevlar undies snuggly secured)
Toodleoo!
Ron Hebbard.

 

[dvsDave]

@lightman02 Have you been told today sonny or is communication and reading beyond your social skill-set along with basic politeness "which you obviously don't get" either?
This old blind dude'll quit typing now and crawl back into my own hole as I sense the proximity of @dvsDave 's silver deletion hammer about to descend heavily upon me. How's that @GreyWyvern and @TimMc ? (Kevlar undies snuggly secured)
Toodleoo!
Ron Hebbard.

It's not silver, it's Palladium, and I don't feel like going to get my hammer right now. But I will just ask that everyone plays nice. @lightman02 this is part of what makes ControlBooth what it is. Our community culture is that we do the job properly, to code, because you don't know who or how equipment might be used down the line, and cutting corners today might involve coroners tomorrow. Safety is our top priority, regardless of potential for harm.

 

[BillConnerFASTC]

Here I thought sharing and learning were top priorities.

 

[dvsDave]

Here I thought sharing and learning were top priorities.

That too.