# Help me understand my electrical panel **URL:** \ **Category:** Factual Questions\ **Created:** [October 16, 2013, 6:31pm UTC](https://boards.straightdope.com/t/help-me-understand-my-electrical-panel/671422 "2013-10-16T18:31:35Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Cardinal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardinal/32/4000_2.png) [@Cardinal](https://boards.straightdope.com/u/Cardinal)\ **Post date:** [October 16, 2013, 6:31pm UTC](https://boards.straightdope.com/t/help-me-understand-my-electrical-panel/671422/1 "2013-10-16T18:31:35Z")
[http://i86.photobucket.com/albums/k110/flavord/Electricalpanel\_zps81d17a41.jpg](http://i86.photobucket.com/albums/k110/flavord/Electricalpanel_zps81d17a41.jpg) Here is a picture of the panel and breakers. 1 is a 120v circuit that controls breakers A and B. 2 controls C and D. A volt meter across 1 and 2 shows 238.7v potential. What we need is 220v to put into a transformer to create 208v for big copiers. So, my ignorant questions are: If we put pigtails into the transformer from an outlet using B and another using C, do we get 20 amps or 40? Since amps is the number of electrons involved, I am guessing 40 amps. So then using A to C, do we get 35 amps? If we put in conduit and ran wire directly from 1 and 2, would we then get 35+40=75 amps? If so, we could run one thick wire from each and run 220v capable extension cords from a transformer. If this were done, we actually would be getting the total amps available to this side of the building, right, not just what would trip the breakers if the amps got to those indicated levels. This is not as preferable as being able to find 220v and enough amps from the wall, though. For the people who are going to tell me to go find an electrician, we’re just discussing our possibilities for now. We have no intention of burning down the building. Afterthought: Why do I hear so much about American 110v being standard, but people also mention 120v offhandedly? This seems to be 120v. Are properly made devices supposed to be able to handle the difference without further trouble? ---
**Author:** ![Chefguy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chefguy/32/138_2.png) [@Chefguy](https://boards.straightdope.com/u/Chefguy)\ **Post date:** [October 16, 2013, 6:45pm UTC](https://boards.straightdope.com/t/help-me-understand-my-electrical-panel/671422/2 "2013-10-16T18:45:58Z")
> [@Cardinal](#): > > Afterthought: Why do I hear so much about American 110v being standard, but people also mention 120v offhandedly? This seems to be 120v. Are properly made devices supposed to be able to handle the difference without further trouble? I’ll let someone else wrestle with your problem, but here, from Wiki: > [@](#): > > In the United States[3] and Canada,[4] national standards specify that the nominal voltage at the source should be 120 V and allow a range of 114 to 126 V (RMS) (−5% to +5%). Historically 110, 115 and 117 volts have been used at different times and places in North America. Main power is sometimes spoken of as 110; however, 120 is the nominal voltage. ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [October 16, 2013, 6:56pm UTC](https://boards.straightdope.com/t/help-me-understand-my-electrical-panel/671422/3 "2013-10-16T18:56:53Z")
Does the copier really need 208? Usually, big beasties like that have internal “taps” that can be changed to let it run on 208 or 220/240 so you can skip the transformer. Or, it may be capable of handling anything from 208 to 240 without needing any wiring or settings changes - the copier manufacturer should be able to clarify this for you. As for the panel, you can not connect anything to terminals 1 and 2. They are the incoming feed to the panel. If you want to use breakers B and C, you’ll have 20 amps of 240, but you need to replace those two breakers with a [“two-pole” breaker](http://www.wiringdoneright.com/breakertypes/double-pole-circuit-breaker.jpg)- the breakers’ levers are connected so if one side of the circuit trips, the other side will be tripped. While you’re getting a new breaker, you should check what the current load for the copier really is - if it can run on 20 amps, great, but if it needs more, you’ll need to investigate the power source to that panel to ensure more power is available. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [October 16, 2013, 7:03pm UTC](https://boards.straightdope.com/t/help-me-understand-my-electrical-panel/671422/4 "2013-10-16T19:03:28Z")
when using 220V you need a dual breaker to shut off both hot lines. you need to get an electrician to see if the correct breakers can be put in your box to give you want you want. ---
**Author:** ![Capt\_Kirk](https://avatars.discourse-cdn.com/v4/letter/c/779978/32.png) [@Capt\_Kirk](https://boards.straightdope.com/u/Capt_Kirk)\ **Post date:** [October 16, 2013, 7:04pm UTC](https://boards.straightdope.com/t/help-me-understand-my-electrical-panel/671422/5 "2013-10-16T19:04:47Z")
Running directly from 1 & 2 is not an option as it would violate code, for a good reason there is no overcurrent protection. Your voltage is normal for a split off a 480v feeder line. Are you positive you need 208v for the copiers? I do have to recommend an electrician for this one because A. that box looks full B. the extension cord from 2 outlets is a very unsafe idea. Good luck and be careful **Capt** ETA yes a double pole breaker is required as said above ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [October 16, 2013, 7:24pm UTC](https://boards.straightdope.com/t/help-me-understand-my-electrical-panel/671422/6 "2013-10-16T19:24:06Z")
> [@Cardinal](#): > > If we put pigtails into the transformer from an outlet using B and another using C, do we get 20 amps or 40? Since amps is the number of electrons involved, I am guessing 40 amps. So then using A to C, do we get 35 amps? No, you would get 20 amps for B and C. All the amps would run through each of the two in series. For A and C, you’d only get 15 amps before A trips. ETA: Note also that the _wires_ only support 15 or 20 amps safely. ---
**Author:** ![Running\_with\_Scissors](https://avatars.discourse-cdn.com/v4/letter/r/a183cd/32.png) [@Running\_with\_Scissors](https://boards.straightdope.com/u/Running_with_Scissors)\ **Post date:** [October 16, 2013, 7:24pm UTC](https://boards.straightdope.com/t/help-me-understand-my-electrical-panel/671422/7 "2013-10-16T19:24:13Z")
Unless I’m mistaken, 208V is the result of using two legs of a three-phase system (common in NYC; probably not in most other places). Most high-voltage machinery is designed to run on anywhere from 208-240V (it will just pull more current at the lower voltage). So IMO you shouldn’t need the transformer, but I’d check the manual for the copier just to be sure. ---
**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:** [October 16, 2013, 8:19pm UTC](https://boards.straightdope.com/t/help-me-understand-my-electrical-panel/671422/8 "2013-10-16T20:19:00Z")
> [@Running\_with\_Scissors](#): > > Unless I’m mistaken, 208V is the result of using two legs of a three-phase system (common in NYC; probably not in most other places). Yes. In a typical 3 phase system the voltage from any of the three hot lines to neutral is 120 volts, but the voltage from any hot line to any other hot line is 208. Residential service in the U.S. is usually a single split phase (meaning a single transformer that is center tapped, with the center tap being the neutral). This gives you 120 volts from either line to neutral and 240 volts from line to line. There are some areas where 2 lines out of a 3 phase system are used in residential service. NYC, as mentioned, is one of them. I think there are also some in Chicago and in a few other places around the country. In residential service you are correct that 120/208 service is pretty rare. In businesses though it is much more common, all through the U.S. If your building needs a lot of power, the power company will often bring all three phases into it. The end result is 120/208 service throughout the building. Those big office copiers need more power than you can get out of a 120 volt outlet, and because 208 is so common in large office buildings these copiers are often designed to run on 208 volts. Some copiers can run off of either 208 or 240 volts and don’t much care either way. Some of them can run on either but require you to move one of the power wires inside the machine to the correct terminal, and failing to do so may damage the copier. Some are designed for one voltage or the other and can’t be easily changed. YCMV (your copier may vary). ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [October 17, 2013, 3:41am UTC](https://boards.straightdope.com/t/help-me-understand-my-electrical-panel/671422/9 "2013-10-17T03:41:32Z")
Your best bet is to call an electrician he can give you good advice. Check your copier name plate. I bet it is 208/240. ---
**Author:** ![Ranger\_Jeff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ranger_jeff/32/2065_2.png) [@Ranger\_Jeff](https://boards.straightdope.com/u/Ranger_Jeff)\ **Post date:** [October 17, 2013, 5:28am UTC](https://boards.straightdope.com/t/help-me-understand-my-electrical-panel/671422/10 "2013-10-17T05:28:44Z")
It looks to me like that’s a standard split phase 120/240 box and they just ran in 2 legs from a 3 phase system. [del]I guess if you could rearrange those breakers so the double breakers are above where breakers A & B or C & D in the photo and if you could manage to put a[/del] No. Safest bet is to a) find out if you can switch the copier and run on 208 and b) tell the electrician you hire what they say.