what is 2 phase electricity?

horseman34

i walked in on the tail end of an interview last week with claire byrne so i missed the context of the conversation, so what is 2 phase in ireland?

10-10-20

You're looking for context when we don't know the context. :) Who said it and what was the general gist of the conversation?

It might refer to some jurisdictions where power is delivered over two hot wires which are 180 degrees apart.

cml387

I believe that in the UK the railways are fed off a single phase and industry gets the other two (or so I was told).

crusd

https://www.boards.ie/discussion/2058276553/what-is-2-phase-electricity

2 phase is not used anymore as far as I'm aware.

Single phase is what is used in the home. 3 phase is used for generation, distribution and high consumption.

horseman34

https://www.boards.ie/discussion/comment/120021182#Comment_120021182

it was some day last week or maybe the week before, i just totally forgot about it till now, i believe they were talking about rewiring for ev charging

crusd

https://www.boards.ie/discussion/comment/120021225#Comment_120021225

Current Home chargers are single phase, commercial 3 phase. If you wanted fast charging at home you would probably need 3 phase

cnocbui

I thought that would be the context. Ireland has single phase connections to houses, which limits the amount of power that can be delivered to a house, which is why power showers are pathetic. In Australia, houses get a 3 phase power supply which can deliver a lot more power. I had an instant electric hot water heater for the house. There was no storage tank, it just heated the incoming mains cold water in real time. Domestic EV charging rates are limited by single phase.

josip

https://www.boards.ie/discussion/2058276553/what-is-2-phase-electricity

That was Bob Flavin I think who was getting mixed up between here and the US where they use dual phase to deliver 240V.

https://gesrepair.com/guide-to-power-singe-split-and-3-phase/

Bob has a bit of a reputation for getting things wrong.

crusd

https://www.boards.ie/discussion/comment/120021300#Comment_120021300

Even then Dual phase is not 2 phase, just 2 wires delivering single phase

TheWonderLlama

https://www.boards.ie/discussion/2058276553/what-is-2-phase-electricity

I know exactly what this relates to. A "motoring journalist" called Bob flavin was being interviewed by Claire Byrne about Electric vehicles.

Bob said that you might need to rewire your house to install a charger for an EV. He said that using single-phase to charge an EV is dangerous, that ideally, you should use two-phase and three phase was only for industrial use.

1. using single-phase to charge an EV is not dangerous.
2. There is no such thing as two phase electricity. (there was, but it was discontinued in about 1920)
3. 3-phase is not just for industrial applications.

bob is a spoofer, don't listen to Bab.

10-10-20

He has an amusing dedicated thread on the EV forum:

https://www.boards.ie/discussion/2058058393/bob-flavin-motoring-journalist-his-views-on-evs

antoinolachtnai

There certainly are two phase connections in Ireland. A rarity but they do exist. As far as I know this is gotten by winding in opposite directions at the single phase transformer but I am no expert.

Manion

https://www.boards.ie/discussion/comment/120022018#Comment_120022018

You're not an expert but speak with such certainty. What makes you so sure?

horseman34

https://www.boards.ie/discussion/comment/120021700#Comment_120021700

Thanks, but now im even more curious how someone with that kind of reputation got that close to rte, did they not bother to check him out. sounds like he's that fella at the end of the bar that once fought big foot while arm wrestling nessie from the way the other sub is talking about him.

antoinolachtnai

https://www.boards.ie/discussion/comment/120022477#Comment_120022477

I have had sight of connection agreement paperwork for ESB Networks customers where 2-phase is specified.

kirk.

https://www.boards.ie/discussion/comment/120024308#Comment_120024308

I'd be surprised if esbn would do anything non- standard like that

There is 2-phase loads .I've wired for welders that are 230 or 400 .

You can wire them single phase 230v or 2-phase 400v .There's a link on the welder for the voltage setup.

TheWonderLlama

without getting into technicalities, i think its fair to say that two-phase does not exist in normal domestic settings, so Bob is full of it.

kirk.

Can't see it .

If the EV is single phase it'll be off -peak presumably .No need for 2 phases

Antenna

https://www.boards.ie/discussion/comment/120024666#Comment_120024666

It does in America which might have caused the confusion.

They would have two 120V lines in anti-phase (so 240V between them) as well as Neutral to supply high power fixed applicances.

Normal applicances are 120V so the two 120V lines would otherwise be roughly equally divided between sockets and lights in different parts of the house.

10-10-20

https://www.boards.ie/discussion/comment/120025349#Comment_120025349

That was my thinking also.

astrofool

https://www.boards.ie/discussion/comment/120025349#Comment_120025349

It also means that as well as technically being on metric (everything is converted to imperial after the fact) they are also technically on 240V :)

Bruthal.

https://www.boards.ie/discussion/comment/120025349#Comment_120025349

If it is 2 x 120v in opposition, then that is no more 2 phase than a site transformer with 110v and centre tapped to give 2x55v lines each side of the earthed centre tap.

More like a single phase winding split/centre tapped.

A connection between 2 AC points can only really be single phase, regardless of the origin of the 2 conductors.

kirk.

2-phases off a 3 phase board to a 400v welder .Would you call that a 2-phase supply going by the definition of a phase( conductor of an ac system other than a neutral) I dunno

Think i'm right in saying that a 2 phase supply(if it existed) in the op would in fact be a 460v split-phase supply as already said by others

Didn't know if i was talking about that or 2 phase and neutral off a 3 phase supply

I'm getting confused now

Bruthal.

2 phases off a 3 phase supply powering a 400v welder etc would be a single phase supply. There is only a single sine wave between the 2 phases. There would be no way of telling they originally were from a 3 phase supply if only testing at the 2 conductors apart from knowing 2 phases would likely be what's supplying the 400v.

Antenna

https://www.boards.ie/discussion/comment/120029170#Comment_120029170

The big difference (with American 240 V) is that there is Neutral between both. A 240 V heating appliance there may have one heating element between one 120 line and neutral, another heating element between the other 120V line and neutral. Things like fans (in a cooker) are likely 120V on one 'phase' or the other . So surely is is technical sense to refer to it as a 2 phase supply ?

The building site transformers, there is no neutral between both lines supplying what it powers, so yes in that case yes you wouldn't call it 2 phase, it is one phase to whatever is drawing power (even though relative to earth it is two 55VAC lines in antiphase)

kirk.

https://www.boards.ie/discussion/comment/120031397#Comment_120031397

The 110v site supply is called 'reduced low-voltage' here

I'd say bruthal has it right as the term Split- Phase 120-0-120 implies 1 phase so you wouldn't call it 2- phase

Maybe 2- phase and N off a 3P board you could call that a 2-phase supply I suppose?

Bruthal.

https://www.boards.ie/discussion/comment/120031397#Comment_120031397

The site transformer centre tap will work perfectly fine as a N if you put loads between it and the poles.

So we're all agreed that there's no such thing as 2 phase electricity here, and that Bob "2 phase" Flavin is a moron?

RetroEncabulator

Normal domestic American power is the old Edison or Westinghouse derived split single phase system. It's certainly not 2-phase. There's a centre tapped transformer on the pole outside delivering two lives and a neutral, which is only used with the split phases, for 240V no neural is present at all. Exactly the same as a site transformer here used on construction sites, except twice the voltage and they use a grounded neutral. It would be like taking 1 leg of the site transformer and a neutral giving you around 55V+0V for most of your sockets, and 55V+55V for the heavier ones.

A similar system, now obsolete existed in Europe with a centre tapped transformer delivering 127V / 220V 50Hz.

In some countries e.g. Italy, there originally was a "lighting" and "power" rate, with different sockets. So you're 127V power competed with gas lighting and was cheaper than 220V, even though the whole thing was coming from the same transformer!

2-phase exists on the continent, but it's mostly obsolete. There are two phase supplies in old buildings in France for example, but the standard is a high powered single phase connection, similar to here or full 3 phase. Some appliances however, at least as used on the continent, may be wired only for 2P+N (not that unusual on hobs).

It's not beyond the realms of possibility that some very old connections here may have been 2-phase back in the day. I know there were some oddities like a few places running 200-210V 50Hz ESB's network too, all of which were removed. Last ones were around the Phoenix Park.

In general in Europe 3-phase is more common than in Ireland and Britain, but it's not universally the case. In some justifications it's limited to pretty much 16 amps per phase, so if you've a single phase supply it's utterly pathetically small, and 3-phase is pretty much the only way of supplying a large home with circuits scattered across the phases.

You may also be getting confusing commentary from say Germany where 1-phase supplies are really only aimed at small single apartments, but they are VERY small compared to what ESB connects as 1-phase. So, you will get people reading stuff about single phase as inadequate when it may not necessarily be.

ESB (in common with the UK) supplies fairly hefty single phase connections.

As for the piece, I don't know what the guy was talking about.

3-phase power is better for EV charging possibilities and powerful heat pumps and so on, but it's just historically not supplied to domestic users here. In a lot of urban areas and anywhere with 4-wire distribution, 3 phase shouldn't be challenging at all, but there are some rural areas with long runs of single phase, where 3-phase might not be available at all without very significant rewiring.

As for single phase being dangerous to charge EVs. That's utter nonsense. It's perfectly safe as long as it's wired correctly and has the correct overcurrent devices installed. The downside is smaller 1-phase connections are just more limited in terms of what they can supply compared to a beefier 3-phase hook up, but Irish connections aren't all that small.