Phase Identifier

[Astra99]

Question for Westie or one of the other DNO people. I recall several years ago when an underground cable "blew" the DNO chap that came out had a inductive device which illuminated red, yellow or blue depending on which phase was inducing the current. Is it possible to buy these, or something similar? At work we are moving the office around, and the last thing I want is to have someone's PC on the red phase and their printer on the yellow! - er - make that brown and black. Thanks in advance.

 

[westie101]

Er yes and they are hugely expensive and consist of quite a bit of kit (or the one we have does)

 

[Lectrician]

Nothing wrong with a PC and Printer on different phases these days. Hell, most buildings are flood wired with network wiring these days, with all multitude of devices all over the place. Phasing is just not considered.

I would imagine anything that glows a different colour for different phases would require some signal to be injected, so would not work without something else being connected elsewhere. I may well be wrong here though.

 

[westie101]

I would imagine anything that glows a different colour for different phases would require some signal to be injected, so would not work without something else being connected elsewhere. I may well be wrong here though.

No, you're right. The one we have I think cost about £3000 a good few years ago. Consists of a signal injection unit (using CTs) a reader & a detector[/quote]

 

[ban-all-sheds]

Nothing wrong with a PC and Printer on different phases these days.

Other than that implies two sockets near to each other with 400V between them.

 

[ricicle]

Nothing wrong with a PC and Printer on different phases these days.

Other than that implies two sockets near to each other with 400V between them.

Still no issue.

 

[Iggifer]

if these circuits are fed from a TP+N board with SP+N MCBs/RCBO's you can just work it out for free with a little investigation and a Socket & See or similar

I had to do a 56 way TP+N board this way, it was interesting to say the least

 

[JohnW2]

Other than that implies two sockets near to each other with 400V between them.

Indeed, but as we've discused before in relation to (probably unhelpful) "400V" warning labels, ... "so what?". In that case, given that a pd of 230V is more than enough to kill, what precautions would one take if one was aware of a 400V pd that one wouldn't take if one knew that the highest pd was 'only' 230V?

The much more important thing (IMO) is to ensure that there is adequate labelling/documention to make people aware of the fact that, although physically close, two sockets are on different circuits and therefore have separate/different means of isolation - but that's as true if they are on the same phase as if they're on different phases.

Kind Regards, John

 

[sparkfish]

Other than that implies two sockets near to each other with 400V between them.

Indeed, but as we've discused before in relation to (probably unhelpful) "400V" warning labels, ... "so what?". In that case, given that a pd of 230V is more than enough to kill, what precautions would one take if one was aware of a 400V pd that one wouldn't take if one knew that the highest pd was 'only' 230V?

The much more important thing (IMO) is to ensure that there is adequate labelling/documention to make people aware of the fact that, although physically close, two sockets are on different circuits and therefore have separate/different means of isolation - but that's as true if they are on the same phase as if they're on different phases.

Kind Regards, John

My thoughts exactley.

 

[ricicle]

The much more important thing (IMO) is to ensure that there is adequate labelling/documention to make people aware of the fact that, although physically close, two sockets are on different circuits and therefore have separate/different means of isolation - but that's as true if they are on the same phase as if they're on different phases.

Kind Regards, John

And competance being a requirement by law in the workplace, and the fact that this is a wiring method that has been around since the dawn of time, any electrician working on the system will automatically be aware that it could be a possibility !

 

[JohnW2]

And competance being a requirement by law in the workplace, and the fact that this is a wiring method that has been around since the dawn of time, any electrician working on the system will automatically be aware that it could be a possibility !

Very true - but what is 'required by law' and what happens in the real world do not always correspond precisely - so some 'aides memoire' would never go amiss!

Kind Regards, John

 

[Astra99]

Thanks to everyone that answered. I will have to go in on a weekend and isolate each ring circuit (six of them) in turn and mark the sockets with the phase. Fortunately the servers and network switches are on dedicated circuits and UPSes.

 

[OwainDIYer]

I don't think you need to mark every socket with the phase it's on (which MCB is more useful, and highlights multiple isolation points), but appropriate labels of "400V between adjacent enclosures" sprinkled around the place where someone is likely to have multiphase connections open.

 

[333rocky333]

I don't think you need to mark every socket with the phase it's on

Although not essential, its quite often marked and convenient.
DB 1 cct 3/L1, DB 1 cct 3/L2, DB cct 3/L3 or R,Y,B on older installs, very handy for routine maintenance so you know exactly what goes off beforehand, quite often a yellow sticker on the DB saying " computer equipment" is also handy especially when not obvious.
I like many others have unknowingly turned off computers by mistake,

I was always led to beleive avoid linking two phases by the data leads also, but that was more when screeded coax type cable was in use back in the day, same with cctv

 

[333rocky333]

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