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#41
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Suggestion for 24V/120V relay to control new outlet?
Twayne wrote:
In , bud-- typed: Twayne wrote: A "Class 2" xfmr is simply a double-insulated transformer without an earth ground on its plug, nor a polarized plug. A "Class 1" xfmr requires a third wire, the earth ground pin on its plug. The "Class of xfmr is a UL/CSA et al classification which approves the xfmr and nothing else as safety approved. The primary characteristic of class 1, 2, and 3 power sources is that they are power limited. There is a specified maximum voltage, current and power you can get from the source. For a class 2 24V transformer the max current is 8A - the maximum current you get if you short circuit the transformer. I think you're confused between class definitions for Safety and what the NEC defines; they are different. I think you're confused about nearly everything. Class 1, 2, and 3 CIRCUITS are classified as remote-control, signaling, and power-limited circuits in the National Electrical Code (NEC). Limiting the discussion to class 2, which many people are familiar with (thermostat, doorbell): Class 2 circuits are class 2 because they are _powered by a class 2 power supply_. Class 1 and 2 Power Supplies determines the insulation PROPERTIES of a power supply and there is no Class 3. To the layman, they either need the third ground wire or not (1 & 2 respectively). So if I buy a UL listed class 2 transformer, according to you, it is not power limited and can not be used to power a class 2 circuit. What a bizarre idea. Make that a stupid idea. No class 3? UL category XOKV - "TRANSFORMERS, CLASS 2 AND CLASS 3". The 8 Amp limitation IN NEC has nothing to do with UL/CSA et al classifications. A transformer can output any current it can be designed for as long as it meets the insulation and overvoltage/current test specifications and meet the safety requirements. That will surprise UL. Class 1, 2, 3 as used in the NEC as you can see above is quite different. While saftey is of course a concern, simply limiting an output to 8 amps would not deem it to be "safe". The NEC is concerned with wiring, and the Safety is concerned with safety. Two different worlds. A google for UL 1459 might be enlightening for you. It might be a lot more enlightening for you. UL 1459 is "Telephone power supplies" (and has probably been withdrawn). You are probably the only person that thinks we are talking about telephones. Class 2 transformers are listed under UL 1585, "Class 2 and Class 3 Transformers." (There is that pesky "class 3" again.) They are power limited "in accordance with ANSI/NFPA 70, ‘National Electrical Code’ (NEC)" Some other standards may be applicable such as UL 1310, "Class 2 Power Units" which also comply "with Class 2 voltage, current and volt-ampere limits as specified in ANSI/NFPA 70, 'National Electrical Code'." Note the reference to the power limits in the NEC. Information is from the UL White Book. Again you are posting nonsense. Four months ago, in a thread about utility PF correction caps, you told HeyBub "next time I'll be a lot more careful." Obviously not. Again. G -- bud-- |
#42
Posted to alt.home.repair
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Suggestion for 24V/120V relay to control new outlet?
You're right, I cited the wrong spec; it's probably actually something like
one of the 5085's. But I'm not tempted to refute anything you say because you are still getting things terribly mixed up. Perhaps you should brush up on how to read these specs too. Like, parts 1 & 2 apply unless excepted by 3 and so forth. Sorry; I don't have the time to mess with your refusal to get the proper information assembled for the project at hand. HTH, Twayne` n , bud-- typed: Twayne wrote: In , bud-- typed: Twayne wrote: A "Class 2" xfmr is simply a double-insulated transformer without an earth ground on its plug, nor a polarized plug. A "Class 1" xfmr requires a third wire, the earth ground pin on its plug. The "Class of xfmr is a UL/CSA et al classification which approves the xfmr and nothing else as safety approved. The primary characteristic of class 1, 2, and 3 power sources is that they are power limited. There is a specified maximum voltage, current and power you can get from the source. For a class 2 24V transformer the max current is 8A - the maximum current you get if you short circuit the transformer. I think you're confused between class definitions for Safety and what the NEC defines; they are different. I think you're confused about nearly everything. Class 1, 2, and 3 CIRCUITS are classified as remote-control, signaling, and power-limited circuits in the National Electrical Code (NEC). Limiting the discussion to class 2, which many people are familiar with (thermostat, doorbell): Class 2 circuits are class 2 because they are _powered by a class 2 power supply_. Class 1 and 2 Power Supplies determines the insulation PROPERTIES of a power supply and there is no Class 3. To the layman, they either need the third ground wire or not (1 & 2 respectively). So if I buy a UL listed class 2 transformer, according to you, it is not power limited and can not be used to power a class 2 circuit. What a bizarre idea. Make that a stupid idea. No class 3? UL category XOKV - "TRANSFORMERS, CLASS 2 AND CLASS 3". The 8 Amp limitation IN NEC has nothing to do with UL/CSA et al classifications. A transformer can output any current it can be designed for as long as it meets the insulation and overvoltage/current test specifications and meet the safety requirements. That will surprise UL. Class 1, 2, 3 as used in the NEC as you can see above is quite different. While saftey is of course a concern, simply limiting an output to 8 amps would not deem it to be "safe". The NEC is concerned with wiring, and the Safety is concerned with safety. Two different worlds. A google for UL 1459 might be enlightening for you. It might be a lot more enlightening for you. UL 1459 is "Telephone power supplies" (and has probably been withdrawn). You are probably the only person that thinks we are talking about telephones. Class 2 transformers are listed under UL 1585, "Class 2 and Class 3 Transformers." (There is that pesky "class 3" again.) They are power limited "in accordance with ANSI/NFPA 70, National Electrical Code (NEC)" Some other standards may be applicable such as UL 1310, "Class 2 Power Units" which also comply "with Class 2 voltage, current and volt-ampere limits as specified in ANSI/NFPA 70, 'National Electrical Code'." Note the reference to the power limits in the NEC. Information is from the UL White Book. Again you are posting nonsense. Four months ago, in a thread about utility PF correction caps, you told HeyBub "next time I'll be a lot more careful." Obviously not. Again. G |
#43
Posted to alt.home.repair
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Suggestion for 24V/120V relay to control new outlet?
Twayne wrote:
You're right, I cited the wrong spec; it's probably actually something like one of the 5085's. But I'm not tempted to refute anything you say because you are still getting things terribly mixed up. Translation: you are wrong but won't admit it. At least you admitted when you were wrong about utility PF correction caps. Perhaps you should brush up on how to read these specs too. Like, parts 1 & 2 apply unless excepted by 3 and so forth. I have no problem reading specs. Like - from UL: Class 2 transformers are listed under UL 1585, "Class 2 and Class 3 Transformers." They are power limited "in accordance with ANSI/NFPA 70, ‘National Electrical Code’ (NEC)" Repeating again - from UL: The transformers are power limited "in accordance with ANSI/NFPA 70, ‘National Electrical Code’ (NEC)" Perhaps you should brush up on the English language. Explain what makes a class 2 door bell circuit class 2. Sorry; I don't have the time to mess with your refusal to get the proper information assembled for the project at hand. Describe your "project at hand". I want to make sure I never get anywhere near it. bud-- n , bud-- typed: Twayne wrote: In , bud-- typed: Twayne wrote: A "Class 2" xfmr is simply a double-insulated transformer without an earth ground on its plug, nor a polarized plug. A "Class 1" xfmr requires a third wire, the earth ground pin on its plug. The "Class of xfmr is a UL/CSA et al classification which approves the xfmr and nothing else as safety approved. The primary characteristic of class 1, 2, and 3 power sources is that they are power limited. There is a specified maximum voltage, current and power you can get from the source. For a class 2 24V transformer the max current is 8A - the maximum current you get if you short circuit the transformer. I think you're confused between class definitions for Safety and what the NEC defines; they are different. I think you're confused about nearly everything. Class 1, 2, and 3 CIRCUITS are classified as remote-control, signaling, and power-limited circuits in the National Electrical Code (NEC). Limiting the discussion to class 2, which many people are familiar with (thermostat, doorbell): Class 2 circuits are class 2 because they are _powered by a class 2 power supply_. Class 1 and 2 Power Supplies determines the insulation PROPERTIES of a power supply and there is no Class 3. To the layman, they either need the third ground wire or not (1 & 2 respectively). So if I buy a UL listed class 2 transformer, according to you, it is not power limited and can not be used to power a class 2 circuit. What a bizarre idea. Make that a stupid idea. No class 3? UL category XOKV - "TRANSFORMERS, CLASS 2 AND CLASS 3". The 8 Amp limitation IN NEC has nothing to do with UL/CSA et al classifications. A transformer can output any current it can be designed for as long as it meets the insulation and overvoltage/current test specifications and meet the safety requirements. That will surprise UL. Class 1, 2, 3 as used in the NEC as you can see above is quite different. While saftey is of course a concern, simply limiting an output to 8 amps would not deem it to be "safe". The NEC is concerned with wiring, and the Safety is concerned with safety. Two different worlds. A google for UL 1459 might be enlightening for you. It might be a lot more enlightening for you. UL 1459 is "Telephone power supplies" (and has probably been withdrawn). You are probably the only person that thinks we are talking about telephones. Class 2 transformers are listed under UL 1585, "Class 2 and Class 3 Transformers." (There is that pesky "class 3" again.) They are power limited "in accordance with ANSI/NFPA 70, National Electrical Code (NEC)" Some other standards may be applicable such as UL 1310, "Class 2 Power Units" which also comply "with Class 2 voltage, current and volt-ampere limits as specified in ANSI/NFPA 70, 'National Electrical Code'." Note the reference to the power limits in the NEC. Information is from the UL White Book. Again you are posting nonsense. Four months ago, in a thread about utility PF correction caps, you told HeyBub "next time I'll be a lot more careful." Obviously not. Again. G |
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