I did peek inside last night, and say that the green wire was tied = directly to the case of the oven, and the other two wires went to a = terminal block then split up into several other wires with varying = colors. I am curious as well for more details inside the oven, but don't want = to open it yet until I know I'll be keeping it (as I'm concerned that = the seller never mentioned I'd need a code to configure it). There's = a bunch of dust in there, so I want to vacuum all of that out also. Cheers, -Neil. Quoting Sean Breheny : > Hi Neil, > > Glad to hear that it worked. This may be pedantic, but the question I > had was not about how 220V single phase works in the US. It was about > how the oven expected to be supplied. The key point was whether the > oven "cared" if its white-colored wire was not at ground potential. It > could be that whoever added the cord to the unit simply used the > colors they had available and that the white wire was not actually > intended to be a neutral. However, it could also be that the > manufacturer intended that wire to be neutral, i.e., current carrying > but at nominally ground potential. Did you ever open up the back of > the oven? I would be curious to see what kind of contacts that cable > attaches to and whether they are labeled or color-coded. > > Sean > > > On Thu, Dec 10, 2009 at 6:48 PM, PICdude wrote: >> Today I spoke with an electrician, who confirmed that yes, this is the >> way 220V single-phase is in the U.S -- 3 wires (ground and two 110V >> legs). =A0So I took the chance and wired up a plug, then ran a test with >> a handful of resistors on a PCB and ... it works!!! =A0I can reflow a >> board with the fixed profiles, but now I need a code to configure the >> profiles, etc, so hopefully the seller has it. >> >> Much thanks, >> -Neil. >> >> >> >> >> Quoting Bob Ammerman : >> >>> In the US, many 220V loads (like baseboard heaters) are wired with a 3 >>> conductor cable: white and black are the two phase wires, green is a sa= fety >>> (frame) ground. No neutral. >>> >>> -- Bob Ammerman >>> RAm Systems >>> >>> ----- Original Message ----- >>> From: "Sean Breheny" >>> To: "Microcontroller discussion list - Public." >>> Sent: Wednesday, December 09, 2009 7:30 PM >>> Subject: Re: [EE] Oven wiring help >>> >>> >>> On Wed, Dec 9, 2009 at 6:41 PM, PICdude wrote: >>>> I did some basic testing... >>>> - Referencing this link again ( http://www.ezdiyelectricity.com/?p=3D2= 38 >>>> ), I get 120V between X and G, 120V between Y and G, and 209V between >>>> X and Y. Both outlets are the same. >>>> - On the oven, the green-wire to ground resistance is effectively zero. >>> >>> This suggests that your building has 208V three phase power and those >>> outlets are wired between two of the phases. The third pin is ground. >>> >>>> >>>> I'm confused by your last paragraph -- why would I not be able to use >>>> the 209V across the two terminals that supplies 209V? Are you saying >>>> that a neutral is required? >>> >>> Well, in principle, no neutral is required. However, the fact that the >>> wire colors are as they are, (i.e., black, white, and green) would >>> indicate that the white should be at the same voltage as ground (i.e., >>> neutral). In many countries (like the UK), 220V standard circuits are >>> wired that way (one hot line which is 220V with respect to ground, one >>> neutral which is nominally at ground potential, and then the safety >>> ground). There is no way for you to provide exactly that configuration >>> (which the colors suggest), since you have no source of 220V with >>> respect to ground, only 220V between two wires which are each only >>> 120V with respect to ground. >>> >>> Most likely, the neutral line is completely isolated from ground in >>> the device itself and it would be OK to connect it to one of the >>> phases and the device would never know the difference. However, there >>> is a chance that doing so could damage it or make it malfunction, >>> since it may expect the voltage between the white and green lines to >>> be small. >>> >>> Sean >>> >>> >>>> >>>> Cheers, >>>> -Neil. >>>> >>>> >>>> Quoting Sean Breheny : >>>> >>>>> Hi Neil, >>>>> >>>>>> From your description, it sounds like it is single phase. I would >>>>> check conductivity (with an ohmmeter) from the green wire to the >>>>> chassis. The green wire should be ground. If that is the case, then it >>>>> is certainly single phase. White is for neutral and black for hot >>>>> (line). >>>>> >>>>> HOWEVER, if you are in the US, I do not think that hot-neutral single >>>>> phase 220V is available. Is this oven meant for US electrical >>>>> standards? 220V outlets in houses in the US usually use two hot lines, >>>>> 180deg apart in phase, plus a ground wire. One hot wire is black and >>>>> the other red, typically. Such outlets will often have only the two >>>>> hots and ground, but there are types which have a neutral, too. >>>>> However, the voltage from each hot to neutral is 110V. >>>>> >>>>> In US industrial installations, the primary power source is usually >>>>> 480V three phase, which is then stepped down to 208V three phase. 120V >>>>> for lighting and outlets is derived by running circuits between one of >>>>> the 208V lines and a neutral which is connected to the wye center >>>>> point tap on the secondary of the 480V to 208V transformer. >>>>> >>>>> 220V devices are usually designed for residential use, but when they >>>>> must be installed in an industrial environment, they are typically >>>>> wired between TWO phases of a 208V three phase supply. If they require >>>>> a neutral, the wye point is once again typically used. This is a >>>>> little bit funky because (A) the total phase to phase voltage will be >>>>> 208 instead of 220, but that is usually within tolerances and (B) the >>>>> phase to ground voltage will not be 50% of the total but a little >>>>> higher (58%, that is 1/sqrt(3) instead of 1/(2)). >>>>> >>>>> So, it sounds to me like your oven, provided that it uses the standard >>>>> wire colors, and is designed for the US, is probably designed to use >>>>> 120V. Do you know what the total required wattage is? Isn't there an >>>>> electrical spec plate on the unit somewhere that would tell you about >>>>> how it should be wired? >>>>> >>>>> If your office receives 220V single phase service (two hot lines, each >>>>> 110V with respect to ground), similar to a US house, then I'd say your >>>>> L6-30 recepticle probably has connections to the two 110V hots and one >>>>> connection to ground. There should be no neutral on this plug. This >>>>> would NOT be able to supply your oven because the three wires coming >>>>> out, at least as indicated by color, have only one hot line and does >>>>> have a neutral. >>>>> >>>>> The Hubbell twist-lock plug could be any of several types. It should >>>>> also have an Lxx-xx number on it somewhere. That would allow us to ID >>>>> it. How many pins does it have? >>>>> >>>>> Sean >>>>> >>>>> >>>>> On Wed, Dec 9, 2009 at 4:22 PM, PICdude wrote: >>>>>> Hi all, >>>>>> >>>>>> Need some quick wiring assistance please... >>>>>> >>>>>> I recently picked up a used reflow oven (APS GF-12) and it does not >>>>>> have a plug -- just 3 bare wires (12ga white, green and black). The >>>>>> prev owner said it was hardwired and thinks it was 3-phase, but IIRC >>>>>> 3-phase requires 4 wires... or not??? >>>>>> >>>>>> I have 2 options for outlets here at the office... >>>>>> (1) a Nema L6-30 ( http://www.ezdiyelectricity.com/?p=3D238 ) >>>>>> (2) Another similar outlet, but the prongs are in a smaller circle. >>>>>> It says "Hubbell twist-lock 20A 250V plug". >>>>>> >>>>>> So I ask... >>>>>> - Is this oven a single-phase oven? (APS only made these as 220V >>>>>> single-phase or 220V 3-phase). >>>>>> - Is there a standard for the colors on the plug wires? >>>>>> - Is there any way to check the oven for the correct phase >>>>>> requirements (resistance tests, etc) before I damage the oven? >>>>>> - Are both of these outlets single phase? >>>>>> - Which wires should I connect to which prongs on the plug? Assuming >>>>>> these plugs are available quickly. >>>>>> >>>>>> Google hasn't yet given me any definitive answer. I have a few days >>>>>> left on my DOA warranty, so need to test fast, and APS won't speak to >>>>>> me unless I give them $2000 first. >>>>>> >>>>>> Much thanks, >>>>>> -Neil. >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> http://www.piclist.com PIC/SX FAQ & list archive >>>>>> View/change your membership options at >>>>>> http://mailman.mit.edu/mailman/listinfo/piclist >>>>>> >>>>> >>>>> -- >>>>> http://www.piclist.com PIC/SX FAQ & list archive >>>>> View/change your membership options at >>>>> http://mailman.mit.edu/mailman/listinfo/piclist >>>>> >>>> >>>> >>>> >>>> >>>> -- >>>> http://www.piclist.com PIC/SX FAQ & list archive >>>> View/change your membership options at >>>> http://mailman.mit.edu/mailman/listinfo/piclist >>>> >>> >>> -- >>> http://www.piclist.com PIC/SX FAQ & list archive >>> View/change your membership options at >>> http://mailman.mit.edu/mailman/listinfo/piclist >>> >>> -- >>> http://www.piclist.com PIC/SX FAQ & list archive >>> View/change your membership options at >>> http://mailman.mit.edu/mailman/listinfo/piclist >>> >> >> >> >> >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- = http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist