How to detect the phase wire in AC?

[J_Nichols]

I'm working with ac from 220 Volts to 30,000 volts and I want to know what tools can I use to detect the phase wire.

 

[crutschow]

What is the "phase wire"?

 

[MrAl]

Hi,

Maybe the "hot" wire?
Sometimes there are two or three phases.

 

[Nigel Goodwin]

What is the "phase wire"?

To be honest I thought 'phase' was an American term

We use 'live' in the UK, but presumably (from the proceeding posts) you use 'hot'.

 

[tvtech]

I'm working with ac from 220 Volts to 30,000 volts and I want to know what tools can I use to detect the phase wire.

Okay. 220VAC to 30KV......smacks of TV stuff??

Tell me/us all and we can help.

You lost me with the "phase wire" though. Because...their ain't one. Not in a TV application anyway

Explain..and tell us All.

Regards,
tvtech

 

[alec_t]

If by 'phase' you do mean 'live' or 'hot' and you don't already know the answer to your question you shouldn't be playing with 220VAC or above. It can KILL YOU !

 

[scubadog]

I am in the Uk and Phase is the term usally used for the live or hot wire.

Most likley used on three phase systems.

You need a prooving unit and need to now how to use one correctly.

This would have been taught on a city and guilds or NVQ qualification......asuming you have one??

If you do have a qualification then how come you are not aware of how to test this??

Seing as you do not know how to use theese tools or work safely with voltges then I would suggest you do not touch it. Those voltages will easily kill you.

 

[J_Nichols]

Sorry for the inconvenience, with the "phase wire" I mean the active wire. At home I've the phase and the neutral wire, in monophasic power. I don't know if I've explained it well.

 

[tracidfish]

Phase is a perfectly acceptable term in the UK and Europe.

It is used widley in industry and in engineering.

 

[Nigel Goodwin]

Phase is a perfectly acceptable term in the UK and Europe.

It is used widley in industry and in engineering.

But FAR more common in the UK is the 'live' wire, and as he's not an industrial user 'phase' wouldn't be used at all

But as with most of these vague threads, he needs to explain FAR more what he's asking, as it makes no sense.

But the 'answer' is quite simple, the live wire is the brown one that connects to the live pin in the mains plug.

 

[cowboybob]

I'm working with ac from 220 Volts to 30,000 volts and I want to know what tools can I use to detect the phase wire.

If I'm interpreting the OP's basic question correctly, he/she wishes to know what tool to use to detect the 220 "hot" wire in a home electrical system (I can't speak to the "30,000" volts issue - that strikes me as a nonsequitor).

I'm pretty sure that UK outlets have the normal Ground/hot/safety(or earth) 3 wire (or plug pin) arrangement. That being the case, the OP can use a simple DVM, or some other voltage detecting device in the following manner:

1. Check the voltages between ALL the possible combinations of what we'll call the 3 wires (or pins) A., B., and C.

2. For example: Upon testing, let's say that pins A-B = 220, pins A-C = 220 and pins B-C=0. Since Ground and Safety (earth) are equivalent for this test, A is "hot" or "phase".

Now, if we're dealing with only a 2 wire system, the OP will have to somehow arrange to to use a metal water pipe (or other grounding return) for the test, but the method would be the same.

And, of course. extreme CAUTION must be exercised whenever dealing with MAINS power.

 

[Nigel Goodwin]

I'm pretty sure that UK outlets have the normal Ground/hot/safety(or earth) 3 wire (or plug pin) arrangement.

The UK uses 3 pin fused plugs (rated at 13A), with live (brown wire), neutral (blue wire) and earth (green/yellow stripped wire) - so there's nothing to test, the colours of the wires tell you which is which, and the specific pins on the plugs tell you which is which as well.

 

[cowboybob]

The UK uses 3 pin fused plugs (rated at 13A), with live (brown wire), neutral (blue wire) and earth (green/yellow stripped wire) - so there's nothing to test, the colours of the wires tell you which is which, and the specific pins on the plugs tell you which is which as well.

Nigel,

Is that the arrangement in the appliance plug or the socket?

Reason I ask is that I can see being able to rely on the appliance plugs being predictable (for the most part), but, from experience here in the States, I have come to be very cautious assuming the socket wiring was done correctly by an electrician (or homeowner).

Generally the plugs (or lights, fan, whatever) are wired per code, but on the off chance of an error, for my part, I always check for the hot lead with a meter first, even if I've turned off the breaker for what I think is the appropriate circuit. Been bitten enough times to assume the worst.

And since you'all routinely deal with 220vac, that's twice as dangerous than what is normal for our single phase 110vac (I'm assuming your 220vac is single phase, given your description of the plug wiring)...

Just askin'.

 

[MrAl]

Hi,


The word "phase" comes from the fact that a single phase is one sine wave which can only have one phase, and three phase has three sine waves at different angles to each other (120 degrees).

Also, 'phase' is not the same *exactly* as 'hot'. Here in the US we have commonly three phase, which is 3 different sine waves 120 degrees apart, but we also have single phase three wire which actually has two hot wires and is sometimes incorrectly called "two phase". The correct nomenclature then is "split phase", or sometimes just "single phase 120/220" or similar. Split phase has two hot wires where the "phases" are 180 degrees apart, but it's still not called two phase.

Any "phase" wire (or "hot" wire or "live" wire) should show a significant voltage level from that wire to ground as well as from that wire to neutral. So in 120v systems you should see around 120vac from the 'phase' wire to ground as well as from the phase wire to neutral, and for 220vac systems you should see 220v from the phase wire to ground and to the neutral. When i say 'ground' here i mean an actual earth ground where sometimes a cold water pipe is used for the measurement. Here we have to be careful though these days, because plastic water pipe is now very common in the US in new construction so it may not provide a good earth ground for the measurement.

 

[Nigel Goodwin]

Nigel,

Is that the arrangement in the appliance plug or the socket?

Both.

Reason I ask is that I can see being able to rely on the appliance plugs being predictable (for the most part), but, from experience here in the States, I have come to be very cautious assuming the socket wiring was done correctly by an electrician (or homeowner).

Generally the plugs (or lights, fan, whatever) are wired per code, but on the off chance of an error, for my part, I always check for the hot lead with a meter first, even if I've turned off the breaker for what I think is the appropriate circuit. Been bitten enough times to assume the worst.

Electrical systems here seem to be a lot better than the states, both in homes, and the infrastructure - cascading failures for example are unknown here.

Makes sense though to ALWAYS double check, you can't usually see where the wires go, and you never know if that particular area you're working on might just have been wired in some weird and wonderful fashion

And since you'all routinely deal with 220vac, that's twice as dangerous than what is normal for our single phase 110vac (I'm assuming your 220vac is single phase, given your description of the plug wiring)...

It's actually 240V here (nominally 230V across the EU, but we're still 240 and the rest are still 220 ) - basically equipment has to be made for 230, and be happy at >240 and <220.

Single phase here with 3 phase distribution, and alternate houses connected to alternate phases to spread the load evenly.

I don't know as 240V is much more dangerous?, there seems no shortage of deaths in the USA from 110V

 

[MrAl]

Both.



Electrical systems here seem to be a lot better than the states, both in homes, and the infrastructure - cascading failures for example are unknown here.

Makes sense though to ALWAYS double check, you can't usually see where the wires go, and you never know if that particular area you're working on might just have been wired in some weird and wonderful fashion



It's actually 240V here (nominally 230V across the EU, but we're still 240 and the rest are still 220 ) - basically equipment has to be made for 230, and be happy at >240 and <220.

Single phase here with 3 phase distribution, and alternate houses connected to alternate phases to spread the load evenly.

I don't know as 240V is much more dangerous?, there seems no shortage of deaths in the USA from 110V

Hi there Nigel,


If i take two alligator clips connected to a power source and clamp one on your right ear and one on your left ear, which would you rather me apply: 120vac or 240vac ? (ha ha)

Really though the higher the voltage the more dangerous it is considered, but there's too many other factors to go into in order to figure out what one is more dangerous statistically. We could look at the number of people that died in each area, but that would not tell us why they died. I've wondered whether or not people living with 120vac are less safety minded than people that live with 240vac. I know one thing, if i was living with 240vac (and i wouldnt mind the benefits from that) i'd be more careful in general when around wiring and plugs and things. 240v has the ability to produce 4800 watts of cooking power with a 20 amp circuit, while 120v only has the ability to produce 2400 watts. So any tiny cell stimulation will be double which means it is twice as likely to get destroyed.

Hopefully the GFI's are helping this situation.

 

[WTP Pepper]

By Phase I assume you mean the live wire. Many DIY outlets sell detectors so you don't drill into a live wire.

 

[ericgibbs]

The correct terminology is LINE and NEUTRAL, not Live and Neutral.

Modern UK fused mains plug Wiring standard is Brown Wire to LINE [the plug connection with the internal fuse] and Blue wire to NEUTRAL, if an EARTH wire is used its a Green/Yellow wire.

https://www.bs1363.com/

 

[tracidfish]

But FAR more common in the UK is the 'live' wire, and as he's not an industrial user 'phase' wouldn't be used at all

But as with most of these vague threads, he needs to explain FAR more what he's asking, as it makes no sense.

But the 'answer' is quite simple, the live wire is the brown one that connects to the live pin in the mains plug.

30Kv sounds pretty industrial to me!

Only cowboys and house basher refer to "Live" Engineers and industrial sparks would use the term "Line" or "Phase".

Do not rely on this the neutral can still be live!

 

[Nigel Goodwin]

30Kv sounds pretty industrial to me!

As you don't have the slightest point of reference how would you know?. More likely it's referring to CRT TV, or a tesla coil

Only cowboys and house basher refer to "Live" Engineers and industrial sparks would use the term "Line" or "Phase".

The website Eric posted above clearly says LIVE as well

BS 1363-1 specifies requirements for 13 A fused plugs having insulating sleeves on line (or always quoted as live) and neutral pins, for household, commercial and light industrial purposes, with particular reference to safety in normal use.

Line might perhaps be used industrially?, but live is used domestically.