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I'm wondering why in my house I have a tied-together pair of breakers (one breaker for the hot line, the other for the neutral) for one geyser, while my other geyser only has its hot line with a breaker on it, while its neutral is simply connected to the terminal strip with all the neutrals.

I don't need to upload a picture: the two breakers are really next to to each other and tied together (sold as one single two-pole breaker unit), so that the operating handle is common to both. If only one trips, the other is forced to do so as well.

So what is the need to have a breaker on the neutral? Are there situations where the overload will be felt only on the neutral and not on the live, or is it simply a trick to accommodate possible wiring errors down the line, i.e. somebody swapping by error the live and the neutral? My setting is a home single-phase 240V line, 15 amps breaker (was ok for the geyser alone, but I added a washing-machine and it now trips when using the washing-machine heating element. So that I contemplate changing it to a 20amps or 25 amps).

EDIT: I am in South Africa, and here is an image (the two-pole breaker we're talking about is the last on the left)

enter image description here

  • What is a household "geyser"? I expect it is British for a fountain or water purifier or something like that. – wallyk Jul 8 '14 at 1:38
  • sorry for my long comment below. geyser = water heater. The other one I have in the house, more recently put, has its live line with a breaker on it but the neutral is just connected directly to the neutral bus in the one and only electric board I have in the house. To me, this is pretty much what I would expect for all appliances. I do fully agree with you I have to exercise caution if I dare replacing the 15A breaker for a 20A, but if I'm pretty sure I know the two wires run uninterrupted from one end to the other, should just check their diameter to be sure they can cope with 20A, right? – jaybee Jul 8 '14 at 7:52
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What you have is a 240V breaker and circuit. The white is NOT a neutral, but being used as another hot...which is perfectly fine and legal. Newer codes require such a white to be re-marked as a hot.

DO NOT replace ANY breaker with one that is larger. 99.9% of the time the wiring is appropriate for the breaker feeding it. Installing a larger breaker could create a fire hazard.

  • mmm - I suspect (language, mention of 240V single-phase line) jaybee is not in the US, so US-electrical assumptions will not apply. – Ecnerwal Jul 7 '14 at 20:55
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    @Ecnerwal I don't think anywhere in the world puts breakers on the neutral, so I think it's safe to say it's used as a hot conductor. It's also probably safe to say not to up size a breaker, without changing the wiring. – Tester101 Jul 7 '14 at 21:38
  • @Ecnerwal, I'm not sure of any other place that uses black and white for 240V. Most of the EU uses blue and brown, as well as many other countries. – Speedy Petey Jul 8 '14 at 1:24
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    OP's profile says Cape Town, South Africa. – DoxyLover Jul 8 '14 at 5:02
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    @jaybee In the US the black wire is the hot wire. Because of the many different wiring standards you should indicate your place of residence in your question. One or more pictures may be helpful as well. – Brad Gilbert Jul 8 '14 at 21:59
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I there,

So finally I swapped the old two-pole 15A circuit breaker with a new 20A circuit breaker. The old one was also breaking the neutral line (black cable here in South Africa) for no really valid reason (unless someone provides us with one here?). So my new one-pole 20A circuit breaker breaks the live line.

I checked that the cable truly powers only my 3kW water heater and the washing machine I added relatively recently (says that the max power of the washing-machine is 2250W, so 10A). And most importantly, I checked that the cables running to the bathroom from the main electrical panel are ok to bear a load of 20A: these are two rigid copper cables of 1.8mm diameter, so a section of 2.5 sq mm.

Thanks, JB

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I have no idea if you're still paying attention to this thread, but those who have provided "answers" missed something, so I'll post now.

Some 240V countries use, in the incoming mains, an "RCD" -- "residual current detector," which is the same thing as us USA folks would call a GFCI. Head on down to your local Home Depot and pick up a single-pole GFCI circuit breaker and you will see that it has connections for the neutral to pass through it as well.

The OP here may very well have a combined main + rcd there, thus explaining the need for neutral to pass through it.

... a 240V country does not have two 120V lines,

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    While there was some confusion in translation, the question was not referring to a neutral as much as it was about questions on wiring, why it is done the way it was, and if it was safe to upgrade the breaker. It appears the idea of neutral was sorted out, and GFCI (RCD) protection never came in to play. – noybman Sep 21 '17 at 4:59

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