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Most GFCI (Ground Fault Circuit Interrupter) outlets are being sold for 120v only. Can it also work for 240v source? Anyone among you has 240v source and yet successfully used any 120v GFCI?

Note in principle a GFCI detects only difference in current. A 240v outlet would have smaller current.. so can we say all 120v GFCI outlets can work for 240v source?

Does the power source of the GFCI circuit uses switching adapter technology or fixed voltage step down transformer?

  • Why don't you simply use a 240V (two pole) GFCI breaker? – ThreePhaseEel Oct 22 '18 at 23:02
  • For a life safety device such as this, I wouldn't play games. Look for a device designed to work with your country's electric wiring system. A quick search on Amazon finds plenty of 2-pole GFCI designed for USA 240V == 2 pole. But if you are in Europe or other areas using 240V in a different way then those devices will likely NOT be what you want - or can use according to your local electrical code. And using a 120V GFCI device is not necessarily going to give you the proper level of protection - or necessarily function at all. Check with a local electrician or supply house. – manassehkatz-Reinstate Monica Oct 22 '18 at 23:06
  • Yes. My country ac system is compatible with the USA since they initially created our power system, however we only use 240V and never the 120V so we don't use neutral. Can these amazon 240v (two pole) GFCI breaker work without neutral connected? I prefer GFCI outlets. But are GFCI breakers more advantageous? Or are GFCI outlets more sensitive? – Samzun Oct 22 '18 at 23:23
  • @Samzun What country are you in? – SomeoneSomewhereSupportsMonica Oct 23 '18 at 8:10
  • Philippines. We used similar ac system as USA but only using the line to line of 240v. We never use line to neutral because we never have gadgets made for 120v. Does the European RCD take split phase of 240v or pure 240v hot to neutral? My loads have no neutral.. only line to line of 240volts. But most important.. does the European RCD have automatic self test (say every 1 minute) to check if the circuit is working or don't they follow the 2015 UL revision? – Samzun Oct 23 '18 at 8:16
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You want to use Euro-style RCD equipment for this

The Filipino power system can be treated as a split-phase, no-neutral (hot-hot) system using TT earthing (Terra-Terra, where the source transformer is connected to an earth electrode and local metal parts are connected to a different earth electrode, but there is no conductor connecting the two earth electrodes). As a result of this, North American distribution equipment is only marginally suitable, as much of it assumes that an earthed neutral is distributed.

Instead, I would use two-pole (1P+N) Euro-style circuit breakers and RCDs (RCBOs, preferably, even, so that local socket-outlets can be used) -- however, instead of a single RCCB or RCBO incomer for the entire system, I would use a regular CB for the incomer and RCBOs with 10mA or 30mA residual (differential) trips for the individual circuits. If you really want to use socket-outlet style equipment, SRCDs can be obtained and used with 10mA trips, but they have the disadvantage that they may not come in a suitable socket style for your local plugs.

(Furthermore, this is forward compatible to what the power utility wants to do over there, which is get you converted over to the IEC/Eurostyle system, full stop.)

  • Problem with getting European RCDs is that these RCDs don't have the sophisticated automatic self-test circuits that US products have. see electronics.stackexchange.com/questions/402520/… If I don't need automatic self-test. I could easily acquire local 240v GFCI (which doesn't have the feature). I need the feature because after installation. I don't want to constantly test it each month. The GFCI with automatic self test would just buzzer you after 15 years when the sensing circuit is destroyed by surge. – Samzun Oct 24 '18 at 3:41
  • @Samzun -- aah. if it makes you feel better -- most USians are pretty bad about testing their GFCIs :P – ThreePhaseEel Oct 24 '18 at 4:12
  • Our locally produced 240v has this written "250V 209A 6mA Sensitivity Rating *UL Safety Level for women and children". Those 2-pole gfci breakers at amazon don't have the sensitivity rating stated.. any ideas what is the typical value? amazon.com/Siemens-MP230GFA-Murray-Circuit-Breaker/dp/… I need a 240v GFCI breaker with 6mA sensitivity and full automatic self-testing feature. – Samzun Oct 24 '18 at 4:41
  • Hi, ThreePhaseEel.. Please share what models are the two Siemens Panels that are not compatible as mentioned by Harper in the thread diy.stackexchange.com/questions/150196/… I'm waiting before I order a PL series pdf.lowes.com/useandcareguides/040892635836_use.pdf to use with my 6 Siemens QF230A 2-pole GFCI breakers... Thank you. – Samzun Nov 10 '18 at 4:44
  • Siemens PL, ES, and EQIII LCs (as well as Murray) all use precisely the same breaker/busbar contact design (and are all labeled for use with Siemens QP and Murray MP breakers, at least on current production units) – ThreePhaseEel Nov 10 '18 at 4:47
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No. A 120V GFCI is not insulated for 240V. Its internal electronics are not made to run 240V.

Worse still, you would be putting 240V on two NEMA 5 sockets, which is asking for a house fire when someone perfectly reasonably plugs in a 120V load, expecting 120V since it is NEMA 5. You can at least avoid this problem by using a deadfront (socketless) GFCI.

Why not just use European GFCIs (the term for them is RCDs)? They are made for 240V.

Or you could use American 240V GFCIs, they do not require neutral (just don't hook it up).

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    but for American 240v GFCI, you need to hook up neutral because it's internal circuitry is using 120v (by tapping hot to neutral)… amazon.com/Siemens-MP230GFA-Murray-Circuit-Breaker/dp/… i'll research about European RCDs.. I wonder they accept 120v line to line (producing 240v like in US) or they need 240v hot and neutral input.. what do you think? – Samzun Oct 23 '18 at 8:02
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    according to this poster jeroen3 "It looks like it can switch 240V, but need the tail connected to neutral for 120V power supply." It's reasonable that the GFCI circuit needs 120v power supply instead of 240v, isn't it? see this chat chat.stackexchange.com/rooms/84813/… – Samzun Oct 23 '18 at 8:48
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    @Harper Per NZ regulations, 30mA RCDs are considered to provide 'personal protection'. 10mA units are required for certain situations (primary schools and medical treatment areas) where people may be at elevated risk. Some RCBOs (RCDs with overcurrent protection) have a functional earth conductor to power the electronics in the event of a lost neutral. Some also only open one pole (but I think these aren't allowed here), so cannot be used with two active conductors. – SomeoneSomewhereSupportsMonica Oct 23 '18 at 21:48
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    Do you have a panel it will fit in? Which would be, specifically, a Siemens panel. Don't buy it unless you do. If you have some other manufacturer's panel, buy their breakers. North American style breakers do not interchange among panels. They seem to, and many will snap in, but they will burn the bus bars if you try. 10kA is the amount of current the breaker can interrupt, i.e. If you have a dead short and it's pulling thousands of amps. It's expressed in SI units. – Harper - Reinstate Monica Oct 25 '18 at 1:30
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    @Harper -- that actually could work OK (it'd be similar to the use of a "zigzag" grounding transformer in a 3ph system) – ThreePhaseEel Oct 25 '18 at 1:49

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