15 vs. 20 Amp NEMA Plug on Lightronics AS-42D

[spotlightondance]

I'm stumped. According to the specs on this dimmer, the AC Input cables are "two 20 amp line cords for connection to 2 separate 120 VAC grounded services in any phase combination. Total capacity of the AS-42D is 4800 watts."

The picture of the dimmer shows what appears to be 15A straight pin NEMA 5-15P plugs on the ends of the AC cables as opposed to NEMA 5-20P straight pin plug (with one pin offset 90 degrees). How are the dimmers rated for 4800W when using 5-15P NEMA plugs?

[derekleffew]

Yup, sure looks like two NEMA 5-15P plugs to me.


Portable Dimming - AS42 Series

The key may lie in the "-UB" and "-UT" suffixes. I can think of no other manufacturer that offers "UL-508 Compliant" as an option.

[fredthe]

The fine print on most of these types of dimmers is that the CORD is rated for 20A, but the plugs are not. If you need to use the full 4800W, then you must replace the plugs with proper 20A plugs. I don't know about these in particular, but I've seen this in other instruction manuals for similar units.

-Fred

[ship]

each of the four dimmers is only rated for 1.2Kw, see under AS-42 in the photo. thats 10a, thus a 15a outlet is fine and in fact a 20a outlet would be incorrect.

[xander]

Actually, each dimmer is only a 1.2k, but there are 4 dimmers and only 2 power supplies. Each plug supplies the power to 2 of these 1.2k dimmers, thus 20A (at 120v). Fredthe is right here, it's most likely the dimmers and cables are rated for 20A, but you would have to add 5-20P plugs to them to actually use them to there full capacity. I think that I brought this up in a post a while back, and I will say it again. I think that this is an extremely dangerous practice that most, if not all, of the shoebox dimmer manufacturers participate in. Many (most?) users of this type of product will see the 1.2k/dimmer and do it without even realizing that the connector is not rated for the load. I don't even understand why they do it. To save the couple dollars that they would have to spend to get 5-20P? Or, I guess it might be because the 5-15P fits in both the 5-15R and 5-20R while you can't plug a 5-20P into a 5-15R and 20A circuits can be rare in the kind of venues these dimmers are marketed for.

-Tim

[mrb]

its not a hazard. the guts (and current carrying capacity) of a 5-15 are exactly the same as a 5-20. The only difference is the blade turned sideways. 5-15 receptacles are legal (as long as its one duplex or more, cant have a single 15a receptacle on a 20a circuit) on a 20 amp circuit. 5-20 receptacles are less common. The only problem is UL wise, anything drawing over 15 amps needs a 5-20 plug, so there is grey area to the legality of it, but safety wise its fine. Its important the user make sure they arent overloading the circuit these are plugged into, but that is important regardless of the plug.

[xander]

I understand that, but it is still dangerous because you can plug it into a 15A circuit when it has a 5-15P. While I know that one should be sure that you are in fact using a 20A circuit, a lot of people (and the percentage of people that fall into this category is far greater with this type of dimmer than say Sensors) don't know to check this and just assume that just because they can plug it in, it's right.

It's just my opinion.

-Tim

[mrb]

Originally Posted by xander

I understand that, but it is still dangerous because you can plug it into a 15A circuit when it has a 5-15P. While I know that one should be sure that you are in fact using a 20A circuit, a lot of people (and the percentage of people that fall into this category is far greater with this type of dimmer than say Sensors) don't know to check this and just assume that just because they can plug it in, it's right.

It's just my opinion.

-Tim

I see your point, but even with the 5-20 plug, and 5-20 receptacles, someone could plug both power cords from the dimmer into the same receptacle and still overload the circuit. Same goes with 5-15 receptacles on a 15a circuit and smaller dimmers.

This has always been a tough dillema, from dimmer packs to 2K fresnels used by the movie guys.....

[JD]

Dangerous is probably not the correct word. Load a 15 amp circuit with 20 amps and the breaker trips.

[derekleffew]

Originally Posted by JD

Dangerous is probably not the correct word. Load a 15 amp circuit with 20 amps and the breaker trips.

Unless it doesn't, at least not until the 14g. wire heats up enough to start a fire. Or it holds during set-up and focus but blows during the show: http://www.controlbooth.com/forums/w...ical-fire.html . Or some well-intentioned but misguided person keeps resetting it: http://www.controlbooth.com/forums/e...ds-matter.html .