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Electronics Forum / Basics / September 2007Power supply w/o ground
A small open-frame line powered power supply (Cincom CFM05S033) doesn't have a ground connection. It will power a tiny device which only has +3.3V/0V DC connections. This will be used in a 6x6x4 plastic enclosure so there is no chassis ground. An electrician will be wiring it in. Is this inherently unsafe? Do I need to find another supply with a ground? >A small open-frame line powered power supply (Cincom CFM05S033) doesn't >have a ground connection. It will power a tiny device which only has >+3.3V/0V DC connections. This will be used in a 6x6x4 plastic enclosure so >there is no chassis ground. An electrician will be wiring it in. > > Is this inherently unsafe? Do I need to find another supply with a ground? I assume you are asking about Earth Grounds. Some devices operate safely with them. You should be go to go ... but it depends on worst cases and possible litigation. > >A small open-frame line powered power supply (Cincom CFM05S033) doesn't > >have a ground connection. It will power a tiny device which only has [quoted text clipped - 6 lines] > with them. You should be go to go ... but it depends on worst cases and > possible litigation. WTH is 'go to go'? It's time to up your meds, again. ;(  SignatureService to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida >> >A small open-frame line powered power supply (Cincom CFM05S033) doesn't >> >have a ground connection. It will power a tiny device which only has [quoted text clipped - 10 lines] > > WTH is 'go to go'? It's time to up your meds, again. ;( Surely the Great Terrell can figure that out? > A small open-frame line powered power supply (Cincom CFM05S033) doesn't have > a ground connection. It will power a tiny device which only has +3.3V/0V DC > connections. This will be used in a 6x6x4 plastic enclosure so there is no > chassis ground. An electrician will be wiring it in. > > Is this inherently unsafe? Do I need to find another supply with a ground? Where did you expect to see a GROUND and why ? Plenty of power supplies don't have them and don't need them. See Class II insulation. http://en.wikipedia.org/wiki/Appliance_classes Graham > A small open-frame line powered power supply (Cincom CFM05S033) doesn't have > a ground connection. It will power a tiny device which only has +3.3V/0V DC > connections. This will be used in a 6x6x4 plastic enclosure so there is no > chassis ground. An electrician will be wiring it in. > > Is this inherently unsafe? Do I need to find another supply with a ground? The AC-to-DC switching regulator power supply you're using has an isolated output, meaning it's constructed so there's no inherent connection between either the positive or negative end of the 3.3VDC supply and anything else. Actually, the data sheet suggests there's more than 4KV isolation between the line voltage input side and the output. I'd take that with a grain of salt, but it does tell you there's no inherent danger involved in either leaving the supply output floating, or grounding it. If you need a grounded supply (think twice before doing this unless you have to -- most times, in industrial applications grounding the supply causes more difficulty than it solves), you can just connect the earth ground wire to the negative terminal of the supply (or the positive terminal, for that matter). "Chris" >> Is this inherently unsafe? Do I need to find another supply with a >> ground? [quoted text clipped - 9 lines] > involved in either leaving the supply output floating, or grounding > it. ** Mere isolation voltage figures tell you ....... NO SUCH DAMN THING !! A given product is either made to meet "Class 2 " ( ie double insulation) safety requirements or it is NOT !! If it is NOT - then all user accessible wiring & exposed metal MUST be connected to safety ground via a solid wire link. If a product does not specifically state that it meets all Class 2 ules - NEVER assume. Someone's life may be on the line. ....... Phil > "Chris" >> [quoted text clipped - 28 lines] > > ....... Phil I am not building a double-insulated Class II device. It is a power supply in a IP65 plastic enclosure, it can potentially be LOCATED OUTSIDE. This "Cincon" (sorry Phil if I offended you.???) supply only has 2 tiny pads exposing the 120VAC to the user, I will cover these with epoxy potting compound. Class I says the chassis should be grounded but the chassis is plastic. There will be an Earth Ground line coming in, should I just connect it to the AC Neutral terminal? Or, is this supply specifically design for Class II and I need to find another? "JT" > "Phil Allison" >> [quoted text clipped - 16 lines] > > I am not building a double-insulated Class II device. ** Sure sounds the hell like you ARE to me !!! Got a clue what one is ?? > It is a power supply in a IP65 plastic enclosure, it can potentially be > LOCATED OUTSIDE. ** Nonsense. External PSU are nearly all required to be Class 2 devices - by LAW !!! Take a look at any wall wart or phone charger. > This "Cincon" (sorry Phil if I offended you.???) ** Your dumb spelling error wasted my time on Google. > Class I says the chassis should be grounded but the chassis is plastic. ** Class 1 requires any output connection to be safety EARTHED !!!!!!!!! > Or, is this supply specifically design for Class II and I need to find > another? ** Read my post. If there are no marking re Class 2 compliance - it damn well AIN'T !!!!!!!! ....... Phil >> "Phil Allison" >>> ** Mere isolation voltage figures tell you ....... NO SUCH DAMN [quoted text clipped - 19 lines] > - by LAW !!! > Take a look at any wall wart or phone charger. Please clarify "external PSU". You imply...external to the product, like a wall wart. My design will have the PSU internal to the product. The entire product and PSU is in the IP65 housing, there are no other connections or outputs. So I think I am still looking at a Class I device, correct? >> Class I says the chassis should be grounded but the chassis is plastic. > ** Class 1 requires any output connection to be safety EARTHED > !!!!!!!!! There are no "outputs". There will be an Earth Ground conductor coming in, should I just connect it to the AC Neutral terminal? > ....... Phil "JT" "Phil Allison" >>>> - NEVER assume. > [quoted text clipped - 12 lines] > > Please clarify "external PSU". ** Your " located outside " will do anytime - FUCKWIT !!!!!!!!!!!!!!!!!!!!!. >You imply...external to the product, like a wall wart. My design will have >the PSU internal to the product. ** Now * I KNOW * you are fuckwit * LIAR * . > The entire product and PSU is in the IP65 housing, there are no other > connections or outputs. ** Nothing at allllllll ??? No user accessible metal parts whateverrrrrrrrr ???? So it does nothing and connects to nothing ??????????? LIKE HELL !!!!!!!!!!!! > So I think I am still looking at a Class I device, correct? ** I reckon you are staring right up you hairy, fat arse. As usual. > There are no "outputs". > > There will be an Earth Ground conductor coming in, ** Why ????????????????????????????????????? > should I just connect it to the AC Neutral terminal? ** If you wanna trip every stinking single ELCB, Core Balance Relay, Safety Switch and RCD in the entire f.cking world. Yeah - go do that. IMBECILE !!!!!!!!!!! ...... Phil > "JT" > "Phil Allison" [quoted text clipped - 10 lines] > ** Your " located outside " will do anytime > - FUCKWIT !!!!!!!!!!!!!!!!!!!!!. Nice grammar, I haven't a clue what you just said. >>You imply...external to the product, like a wall wart. My design will >>have the PSU internal to the product. > ** Now * I KNOW * you are fuckwit * LIAR * . Huh? >> The entire product and PSU is in the IP65 housing, there are no other >> connections or outputs. > ** Nothing at allllllll ??? The entire product and PSU are in the IP65 housing, THERE ARE NO OTHER CONNECTIONS OR OUTPUTS. > No user accessible metal parts whateverrrrrrrrr ???? > So it does nothing and connects to nothing ??????????? > LIKE HELL !!!!!!!!!!!! You saw the picture. Sure, the power supply has "metal parts", if you're counting component leads and solder pads. Your point? >> There will be an Earth Ground conductor coming in, > ** Why ????????????????????????????????????? If I don't need an Earth Ground just say so. >> should I just connect it to the AC Neutral terminal? > ** If you wanna trip every stinking single ELCB, Core Balance Relay, > Safety Switch and RCD in the entire f.cking world. > Yeah - go do that. > IMBECILE !!!!!!!!!!! ...hence my questioning of this suggetion from "Chris". > ...... Phil > There will be an Earth Ground conductor coming in, should I just connect it > to the AC Neutral terminal? Frankly, if you think such an idea is even remotely acceptable you deserve to be shot. Graham <snippage> >There are no "outputs". >There will be an Earth Ground conductor coming in, should I just connect it >to >the AC Neutral terminal? DO NOT connect the earth ground (safety ground, green or green/yellow wire) to the neutral in your equipment. The safety ground should be connected to any exposed metal (or otherwise conductive) parts of your equipment. If your device has no exposed metal parts, do not connect the green (or green/yellow) safety ground to anything. SignaturePeter Bennett, VE7CEI peterbb4 (at) interchange.ubc.ca new newsgroup users info : http://vancouver-webpages.com/nnq GPS and NMEA info: http://vancouver-webpages.com/peter Vancouver Power Squadron: http://vancouver.powersquadron.ca > > "Chris" > >> [quoted text clipped - 30 lines] > > I am not building a double-insulated Class II device. If it's not Class II then it's presumably Class I which requires an earth. > It is a power supply > in a IP65 plastic enclosure, it can potentially be LOCATED OUTSIDE. [quoted text clipped - 9 lines] > Or, is this supply specifically design for Class II and I need to find > another? If you need to ask, quite frankly you shouldn't be building anything like this. I suggest you read up on safety standards. Graham "JT" >A small open-frame line powered power supply (Cincom CFM05S033) doesn't >have a ground connection. ** The brand name is " Cincon " - you PITA. ....... Phil >A small open-frame line powered power supply (Cincom CFM05S033) doesn't >have a ground connection. It will power a tiny device which only has >+3.3V/0V DC connections. This will be used in a 6x6x4 plastic enclosure so >there is no chassis ground. An electrician will be wiring it in. > > Is this inherently unsafe? Do I need to find another supply with a ground? Perhaps someone can suggest how to safely wire and enclose a small 3.3V device with 120VAC power supply for use outdoors. TIA "JT" > Perhaps someone can suggest how to safely wire and enclose a small 3.3V > device with 120VAC power supply for use outdoors. > TIA ** Totally " pot " the damn thing. Polyester resin is top stuff. ..... Phil >>A small open-frame line powered power supply (Cincom CFM05S033) doesn't >>have a ground connection. It will power a tiny device which only has [quoted text clipped - 6 lines] >device with 120VAC power supply for use outdoors. >TIA Why not buy a wall wart with the required output? It will be made to be ungrounded and all the energized parts will be enclosed by the maker so you won't need to worry. By the way, please don't pay attention to phil allison. He is probably in need of professional help but instead spends his time trying to rile up anybody he can online. Just like when CB radios were a big craze and all sorts of shy whackos would get their hands on a radio and broadcast all sorts of stuff pretending to be something or someone they were not. ERS >>>A small open-frame line powered power supply (Cincom CFM05S033) doesn't >>>have a ground connection. It will power a tiny device which only has [quoted text clipped - 16 lines] >pretending to be something or someone they were not. >ERS I've never noticed his technical advice to be incorrect. Of course, he doesn't give technical advice as often as he spews abuse. SignatureAl in St. Lou "Al in Dallas" < > I've never noticed his technical advice to be incorrect. ** Right you are. > Of course, he > doesn't give technical advice as often as he spews abuse. ** Posting specific criticisms and verbal self defence are not abuse. YOUR post IS 10% abuse as it is not specific t any matter and presents your erroneous conclusion as fact. ....... Phil >"Al in Dallas" < > [quoted text clipped - 9 lines] > YOUR post IS 10% abuse as it is not specific t any matter and presents >your erroneous conclusion as fact. Anyone can count how often you use abusive terms such as "fuckwit." They can also count how often you post technical information without being abusive. And I can count. SignatureAl in St. Lou "Al in Dallas" >>> I've never noticed his technical advice to be incorrect. >> [quoted text clipped - 9 lines] > > Anyone can count how often you use abusive terms such as "fuckwit." ** The use of colourful language is not proof of abuse. Posting specific criticisms and verbal self defence are NOT abuse. > They can also count how often you post technical information without > being abusive. And I can count. ** Shame you cannot think. You just see words on a screen but have no idea what it all means. ...... Phil > A small open-frame line powered power supply (Cincom CFM05S033) doesn't > have a ground connection. It will power a tiny device which only has > +3.3V/0V DC connections. This will be used in a 6x6x4 plastic enclosure > so there is no chassis ground. An electrician will be wiring it in. > > Is this inherently unsafe? Do I need to find another supply with a ground? It sounds like it's probably an isolated supply. The only Earth ground you should need should be the frame of the supply - i.e., any metal that a person could touch. If your device needs a real earth ground, then just tie them together at one common point. Otherwise, there should be no problem using it - imagine a 2-prong wall wart, for example. Good Luck! Rich |
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