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Author Topic: Stage drops  (Read 2227 times)

frank kayser

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Re: Stage drops
« Reply #20 on: July 18, 2014, 03:19:40 pm »

Why build it with a 5-20 and attach a 5-15 adapter?  Doesn't make sense really, but maybe I am being thick headed.

Because you what the cable to be able to take 20amps, but you know you will often only have 15amp circuits available. The 5-20p would prevent you from plugging into a 15amp only plug, which is silly.


I dare say Samuel is right - silly.  And no, Stephen, you're not being thick headed.  The practical reason is as Samuel states - not too many 5-20 outlets around, it seems.

For example, I know my kitchen is wired 12ga/20amp breaker, but all receptacles are 5-15 (I was under the impression that was a no-no)  I don't own anything with a 5-20 plug, and I can't remember seeing any appliance that ever did.  Code says to use the proper receptacle based on wire gauge and breaker, but realistically, why bother?

I'm not sure I've seen a 5-20 receptacle at my jobs, except the GFCI devices on the plaza of town.  I know I've run my rig off one outlet time and time again.  Was it 15 or 20 amp?  Dedicated?  How much was I really drawing?

The 5-15 plug goes into a 5-20 outlet anyway.  And I'm guessing the 5-20 to 5-15 adapter isn't UL listed, either...

I'm guessing that most small operators just plug stuff into a stringer really not knowing the load they're putting on it.  They may "know their rig will run on one or two 20 amp circuits". Seems like it's spread'em out, plug'em in, and hope for the best. Some of the more experienced are giving some thought to the load.  Others is load it up 'till the voltage sags, or the breaker pops.

Really, how many 1kw class D amps can one put on a 15 amp circuit, anyway? 
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Jonathan Johnson

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Re: Stage drops
« Reply #21 on: July 18, 2014, 03:28:26 pm »

Why build it with a 5-20 and attach a 5-15 adapter?  Doesn't make sense really, but maybe I am being thick headed.

At first glance, it does seem a bit silly. Since every 5-20 (20A 120V) receptacle accepts a 5-15 plug, why not just put a 5-15 plug on the cord to begin with?

In order to get the 20A rating that is advertised, you can't put a 15A-rated plug on the cord. Even if there is no difference in the electrical properties of the 15A and 20A plugs, and the 15A plug *could* handle 20A of current continuously, the orientation of the prongs determines the rating in the eyes of regulatory, testing, inspection, and standards agencies. Hence the adapter.

As it is, the receptacles on the cordset are rated at only 15A. But when summed together, the total loads could exceed 15A.

In my opinion, every extension cord that is rated lower than the circuit it can connect to should be equipped with a fuse or circuit breaker (as they are in Europe). Many fires have started because someone overloaded a 16AWG extension cord plugged into a 20A circuit -- and the properly sized and functioning circuit breaker never tripped.
« Last Edit: July 18, 2014, 03:36:48 pm by Jonathan Johnson »
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Jonathan Johnson

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Re: Stage drops
« Reply #22 on: July 18, 2014, 03:38:02 pm »

The 5-15 plug goes into a 5-20 outlet anyway.  And I'm guessing the 5-20 to 5-15 adapter isn't UL listed, either...

There is no reason why the adapter (5-20R to 5-15P) couldn't be UL listed. The adapter effectively derates the cordset to 15A, but may be designed to be capable of passing 20A safely. However, there could be an issue if it is connected to a 5-15R receptacle on a 20A circuit (a practice permitted in residential and some commercial installations in the US) and the receptacle cannot handle 20A current through the face.
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TJ (Tom) Cornish

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Re: Stage drops
« Reply #23 on: July 18, 2014, 03:46:37 pm »

There is no reason why the adapter (5-20R to 5-15P) couldn't be UL listed. The adapter effectively derates the cordset to 15A, but may be designed to be capable of passing 20A safely. However, there could be an issue if it is connected to a 5-15R receptacle on a 20A circuit (a practice permitted in residential and some commercial installations in the US) and the receptacle cannot handle 20A current through the face.
This whole issue is a code cluster, and stupid, IMO.  5-15 receptacles are virtually always listed as having a 20A pass-through, which is why it's acceptable to use a 5-15R on a 20A breaker (assuming appropriate 12ga wire), since the assumption is that multiple devices will share the load on a circuit.

That is a lame assumption and design; courtesy of grandfathered old systems with 14ga 15A wiring.  Assuming that the appropriate OCPD is in place, there's no safety issue attempting to use a device that attempts to draw more than 15A - it's the OCPD's job to protect the wiring, not relying on the load being "nice".  The only benefit is possibly saving the user some hassle of having to reset a breaker.

As others have said, there's no electrical capacity difference between the plug - it's just an orientation difference for keying purposes. 

All of my cords have 5-15P and 5-20R, and I proudly thumb my nose at this stupid rule.
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Stephen Swaffer

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Re: Stage drops
« Reply #24 on: July 18, 2014, 03:47:12 pm »

FWIW I usually install 20 A receptacles in commercial/industrial situations-unless there are kids around like a church or school, then I use resi TR recepts.  If you go to a supply house instead of a big box store, my cost difference between a 15A and  20A Hubbel recpt is 10 cents-and my cost is a third or so of what I would pay for a premium receptacle at a big box-so it might pay to shop if you are building a distro.  I know 10 cents a pop can add up-but I like my jobs done a certain way.  I once installed cheap big box recepts in a garage downstream of GFCIs.  They kept tripping the GFCIs-so I replaced them on my dime and that was the end of the penny pinching!

Actually the NEC permits 15A and 20A recepts on 20A circuits, but only 15A on 15A circuits.  Seems odd-but has been that way a long time-likely based on the logic of protecting the installed wiring, external wiring being the users problem.
I doubt there is really any power handling difference between a 15A and a 20A recpt. 

Fused cords would be OK-except that people would just over fuse them-the same reason edison fuse boxes are becoming obsolete and are prohibited as new installs.
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Steve Swaffer

frank kayser

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Re: Stage drops
« Reply #25 on: July 18, 2014, 03:55:47 pm »

There is no reason why the adapter (5-20R to 5-15P) couldn't be UL listed. The adapter effectively derates the cordset to 15A, but may be designed to be capable of passing 20A safely. However, there could be an issue if it is connected to a 5-15R receptacle on a 20A circuit (a practice permitted in residential and some commercial installations in the US) and the receptacle cannot handle 20A current through the face.

True.  And this is where your fusing comes into play.  The cord is fused at 20a.  The adapter is separately fused at 15a.
OT...
How does Europe prevent upsizing of the fuse in the plug - or bypassing the fuse altogether? 


This whole issue is a code cluster, and stupid, IMO.  5-15 receptacles are virtually always listed as having a 20A pass-through, which is why it's acceptable to use a 5-15R on a 20A breaker (assuming appropriate 12ga wire), since the assumption is that multiple devices will share the load on a circuit.

That is a lame assumption and design; courtesy of grandfathered old systems with 14ga 15A wiring.  Assuming that the appropriate OCPD is in place, there's no safety issue attempting to use a device that attempts to draw more than 15A - it's the OCPD's job to protect the wiring, not relying on the load being "nice".  The only benefit is possibly saving the user some hassle of having to reset a breaker.

As others have said, there's no electrical capacity difference between the plug - it's just an orientation difference for keying purposes. 

All of my cords have 5-15P and 5-20R, and I proudly thumb my nose at this stupid rule.


mee too...  ;)


frank
« Last Edit: July 18, 2014, 03:58:06 pm by frank kayser »
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Ray Aberle

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Re: Stage drops
« Reply #26 on: July 18, 2014, 04:14:34 pm »

When I re-wired my house, I just said screw it and put in 20A receptacles everywhere. I figured I would over-engineer a bit. (And opened up opposite walls in each room from 1-gang to 2-gang outlets- never enough outlets in a bedroom, but not a problem anymore! And pulled datawire throughout. And I think we used 10g wiring for the now-meeting-code 2 "small appliance" circuits in the kitchen, the thought being that some day they could up the requirement, and I had the extra cable to do it with. And outdoor circuits that are now required, but I also did 20A switches on them, so you can turn them off from inside.)

-Ray
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Jerome Malsack

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Re: Stage drops
« Reply #27 on: July 20, 2014, 03:18:22 pm »

With the other article about the courts placing liability on each member in the power problem I would agree that not accepting the bands poor broken solutions should not be allowed to connect. 
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Gary Fitzpatrick

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Re: Stage drops
« Reply #28 on: July 23, 2014, 06:56:13 am »

In Ireland/UK alot of these problems are avoided in the residental setting

32amp for a ring main
16amp for a radial spur (not that common)
All household plugs are fused 13amp plugs, and in most of the venues i run sound in, I will run my rig of 1 13amp socket.
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Allen Heath GL2000, EV sx300 over Community pro Subs, EV s-200 monitors, Zeck amplification

Rory Maguire

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Re: Stage drops
« Reply #29 on: July 26, 2014, 05:23:42 pm »

Regarding lampies using NL8 connectors for their AC connections, note the company Selecon who have a range of 80v units. Each lamp comes with a transformer which hangs on the bar next to it, takes a 240v dimmed circuit and outputs 80v to the lamp via NL8.

http://www.seleconlight.com/index.php?option=com_virtuemart&page=shop.product_details&flypage=flypage.p1&category_id=125&product_id=40

Huge savings is power usage I'm told!
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