On 08/07/2017 06:02 PM, John Andersen wrote:
There are a ton of differences in EU and North American power systems as far as physical structure. Its easy to be less familiar than you think you are. This stuff has become more than a little complex with the growth of grids.
Neutral is tied to Ground almost everywhere in the US, if not on your house then on the next nearest pole or power pedestal.
Ummm... Neutral is *ALWAYS* tied to ground at the power entrance. Other services are likewise bonded to the same ground point.
Ground rods are not universally used, because the rely on soil moisture content and can behave very inconsistently. During the dry season its common for some large networks to lose their ground because they relied too heavily on grounding rods which were no longer in good contact.
Actually, ground rods are used, as water mains are no longer a reliable ground. There should also be a ground wire running back to the power line.
Then there are differences between three wire systems (pos, neg, neut) and 4 wire systems (pos net neut ground) that occur in different parts of the world. Some parts of the US have individual houses all on one side (phase), and alternate every other house to the other leg to balance the phases. Then someone strings an extension cord. (Indications are that the US may slowly be moving toward a 4 wire infrastructure. https://en.wikipedia.org/wiki/Three-phase_electric_power
There's no positive or negative with AC power. It's constantly changing polarity. There are 1 or more hot wires and neutral, with ground completely isolated, except where it connects to the neutral at the power entrance. In normal house wiring there are 2 hot wires, 180° apart, with most circuits using only one hot. Heavy loads, such as stoves & dryers, use both. Three phase has been around since Tesla and is used in industrial or large commercial installations. I doubt we'll see 3 phase in homes any time soon, as it would require a lot of major changes, including replacing any 240V appliances. Incidentally, 3 phase only uses 4 wires with the wye configuration, where there is a common point that can be grounded. With the delta configuration, there is no common point that can be grounded and so no 4th wire. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org