# Specialty A/C plug timer **URL:** \ **Category:** Factual Questions\ **Created:** [March 1, 2015, 6:19pm UTC](https://boards.straightdope.com/t/specialty-a-c-plug-timer/713944 "2015-03-01T18:19:53Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![seal\_cleaner](https://avatars.discourse-cdn.com/v4/letter/s/e274bd/32.png) [@seal\_cleaner](https://boards.straightdope.com/u/seal_cleaner)\ **Post date:** [March 1, 2015, 6:19pm UTC](https://boards.straightdope.com/t/specialty-a-c-plug-timer/713944/1 "2015-03-01T18:19:53Z")
Plug is three-pronged, as in - | O Does this type of plug have a name? A/C-heater has no thermostat, looking for a plug in timer. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [March 1, 2015, 6:31pm UTC](https://boards.straightdope.com/t/specialty-a-c-plug-timer/713944/2 "2015-03-01T18:31:11Z")
Is it 120 VAC (NEMA 5) or 240 VAC (NEMA 6)? Google NEMA “5-20P” plug Does it look like that? If so, then it’s probably a 120 VAC / 20 A plug. It can only be plugged in to a NEMA 5-20R receptacle. AS for a timer, not sure. Am googling… ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [March 1, 2015, 6:33pm UTC](https://boards.straightdope.com/t/specialty-a-c-plug-timer/713944/3 "2015-03-01T18:33:16Z")
If you are trying to draw what I think you are trying to draw, it’s a NEMA 5-20P. More people will know what you are talking about if you just call it a 120 volt 20 amp plug though. ETA: Ninja’d. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [March 1, 2015, 6:45pm UTC](https://boards.straightdope.com/t/specialty-a-c-plug-timer/713944/4 "2015-03-01T18:45:53Z")
Grainger has a nice selection of timers. The [INTERMATIC 20XE85](http://www.grainger.com/product/INTERMATIC-Timer-20XE85) is rated for 120 VAC / 20 A. Keep in mind, though, that “hot switching” can be hard on the timer’s switch/relay contacts. In other words, while the switch/relay contacts may indeed be rated for a continuous current of 20 A, opening or closing the contacts under full load can cause arc erosion. An appropriately-rated RC snubber across the load or contacts can help minimize the erosion. A better (but more costly) solution is to use a timer that drives a SS relay with zero-crossing feature. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [March 1, 2015, 7:12pm UTC](https://boards.straightdope.com/t/specialty-a-c-plug-timer/713944/5 "2015-03-01T19:12:15Z")
> [@Crafter\_Man](#): > > Grainger has a nice selection of timers. The [INTERMATIC 20XE85](http://www.grainger.com/product/INTERMATIC-Timer-20XE85) is rated for 120 VAC / 20 A. note 20XE85 is the Grainer vendor part number. HB113 is the INTERMATIC manufacturer part number. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [March 1, 2015, 8:09pm UTC](https://boards.straightdope.com/t/specialty-a-c-plug-timer/713944/6 "2015-03-01T20:09:23Z")
> [@johnpost](#): > > note > > 20XE85 is the Grainer vendor part number. > > HB113 is the INTERMATIC manufacturer part number. Good catch. Thanks. 🙂 ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [March 1, 2015, 8:50pm UTC](https://boards.straightdope.com/t/specialty-a-c-plug-timer/713944/7 "2015-03-01T20:50:56Z")
> [@engineer\_comp\_geek](#): > > If you are trying to draw what I think you are trying to draw, it’s a NEMA 5-20P. More people will know what you are talking about if you just call it a 120 volt 20 amp plug though. > > ETA: Ninja’d. OP needs to be very sure what this is, since NEMA 6-20 (250 volt) is the “reverse” of the 125 volt 5-20; the 6-20 swaps which blade is vertical and which is horizontal. [![](https://www.buildmyowncabin.com/electrical/nema-plugs-receptacles.gif) ](https://www.buildmyowncabin.com/electrical/nema-plugs-receptacles.gif)