Proper way to build 20 amp adapters

[Nelson]

I am building a few edison to stage pin adapters. Normally I would just buy 5-15P (regular male edison plugs) and female stage pin connectors and some 12/3 SO for the adapters. However, I've read elsewhere that technically, the 15 amp plug should not be used because the female end (and cable) is rated for 20 amp. You could connect a 20 amp load to the cable, plug the cable into a 20 amp circuit, and the 15 amp plug would be a weak link.

Realistically, commercial grade 15 amp plugs can probably handle 20 amps, but to be technically correct, should I use 5-20P plugs? In the past, I've made a few adapters with 20 amp plugs when I know they will only be used with 20 amp outlets. But what if I want to plug these adapters into regular 15 amp outlets? Of course, if I did so, I wouldn't try to draw more than 15 amps through the adapter when connected to a 15 amp outlet. If that is incorrect, what is the proper way to connect stage pin plugs to a standard 5-15R outlet?

I'm curious about this both from an NEC standpoint and a practical standpoint (i.e. what does everyone else do in this situation).

 

[rochem]

I'll let someone else speak from an NEC standpoint, but from a practical standpoint, building MEDs with 5-20 plugs is next to useless. Unless you have a specific, semi-permanent location for this adapter (like into a [-]hot pocket[/-] convenience outlet on a dimmer rack [EDIT: but wait, convenience outlets are only 15A as well I think, my mistake]), I'd definitely just build them as 5-15s. Also, many MEDs and FEDs are built with 14/3 cable instead of the more correct 12/3, so then the stage pin becomes the only 20A rated device in the chain. I've only ever built a true 20A MED once for one specific application where I was drawing 18A, but other than that, I've never seen 5-20 connectors on MEDs outside of specialty applications. Even the shops will send you a 20A 2P&G connected with 14/3 to a 5-15, unless you specifically ask for 12/3 - and then they'll probably end up needing to make them for you before sending it out.

 

[gafftapegreenia]

Wow, can't say that I've seem any professional Edison to Stagepin adapters made out of 14/3. I've seen a lot made out of SJOOW 12/3, (which I don't think is code, but I need SteveTerry to chime in on that) but not 14/3. That's a little scary.

Now, if I were making Stagepin to Edison adapters, I would be certain to use 5-20R connectors, as they can accept both 5-15P and 5-20P.

However, in your application, I would stick with the 5-15P connectors. Unless you are in an application where you KNOW you need your adapter to handle over 15 amps, AND you have an outlet that will allow you to draw 20 amps, there's really no point to making it with a 5-20P.

Until someone can prove to me there is physically more copper in a 5-20P and not just one pin turned 45 degrees maybe I'll start to believe in them more. Really, the 5-20P is designed to keep people from plugging a device that draws over 15 amps into an outlet wired with 14 gauge and breakered up to 15 amps. In my opinion, Edison wall receptacles in entertainment venues should, as a rule, be wired standard for 20 amps. 15 amp outlets are barely enough for most home owners these days.

 

[Edrick]

We burn those connectors out quite a bit, plugging 2K fixtures into it. However it's the nature of how it is. The problem is if you used the correct 20A Male and 20 A Female with the turned blade you'd almost never find a place to plug your cord into.

 

[Nelson]

The reason that I would even consider using 20 amp plugs is that all the edison receptacles in our theater are 5-20R, so I could use 5-20P plugs if 15s aren't technically compliant. The only time I would need 5-15P is if I am hooking up instruments somewhere else, such as the school gym, which is rare.

One other reason I sometimes use 20 amp plugs is to prevent someone from picking up the adapter and plugging it into a lightweight household extension cord, then loading the cord with too many lights.

On a similar note, I often build extension cords using 15 amp edisons and 12/3 SOOW cord. I could pull 20 amps through that cord (as long as the voltage drop wasn't excessive, of course), but I am limited by the connector ratings. I would use 20 amp connectors, but then I couldn't plug the cord in everywhere I need to. If a 20 amp stage pin outlet is allowed on the end of a cord with a 15 amp edison plug, why couldn't I build a cord with a 5-15P on one end and a 5-20R on the other?

 

[derekleffew]

2011 NEC 520.69 (A)

No reduction in Current Rating. Each receptacle and its corresponding cable shall have the same current and voltage rating as the plug supplying it. It shall not be utilized in a stage circuit with a greater current rating.

It seems one might interpret that to mean if an adapter uses a 15A male, it must also use a 15A female. The code says "same current and voltage rating as the plug supplying it," not "equal to or greater than." Obviously this is problematic given that there's no such thing as a 15A stage pin connector. Also problematic is that the vast majority of stage circuits are 20A, so a 15A connector would never be permitted.

On another note, 520.69 (C) states that "listed, hard usage (junior hard service)" [SJO] is acceptable if not over 1.0 m (3.3 ft).

I too, have burned up 5-15 connectors on 2K Fresnels, but I seriously doubt anything would be different if using 5-20 connectors.

 

[DrPinto]

A theater I was working at had some adapters that used the 20 amp edison plugs. I changed them to standard 15 amp edisons. When I compared them to each other at the home center, they were exactly the same except for the 1 blade turned sideways (and it cost a lot more). We use 12 gauge wire in all adapters and rarely have a 20 amp load on them.

I'd stay away from the 20 amp edisions. They're just designed to frustrate you in a theater setting.

And good luck if you ever need to plug one into an extension cord.

 

[Nelson]

Thanks for all of the responses. I will continue using 15 amp plugs when building adapters. Even if it might not be compliant, I don't see how using 20 amp plugs would be safer based on our discussions.