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Delboy247
Hi whilst inspecting a job I have come across two circuits supplied from two different phases how should I deal with this as its supplied from two different boards.
- Thread starter Delboy247
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roukel01
unless they are within arms reach then nothing need to be done, if they are within arms reach of each other, then a notice needs to be put in place saying something along the lines of "400 volts exisits between the two sockets" (the exact wording is in the regs somewhere!
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Sintra
Have a read at 514.10 page 93
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Delboy247
They are in arms reach and I will put a notice on cheers.
M
MFHEng
HI
You don't need to mark them the regulation is refering to fixed equipment and not socket outlets, at what point would you have two socket circuits dismantled at the same time? The sockets have the same nominal nominal voltage to earth of 230 volts. It is ambiguos and has been removed from AMD1. Just to clarify, you do not have to identify, with voltage labels ,sockets or note that they are fed from differing phases and therefore pose a 400 volt threat. You would label them normally stating there circuit and phase dsesignation but thats all.
You don't need to mark them the regulation is refering to fixed equipment and not socket outlets, at what point would you have two socket circuits dismantled at the same time? The sockets have the same nominal nominal voltage to earth of 230 volts. It is ambiguos and has been removed from AMD1. Just to clarify, you do not have to identify, with voltage labels ,sockets or note that they are fed from differing phases and therefore pose a 400 volt threat. You would label them normally stating there circuit and phase dsesignation but thats all.
The reg actually refers to equipment and enclosures, enclosures being a rather all-encompassing term!
Guidance Note 1 has this to say:
Warning notice – Voltage
The warning notices regarding voltage concern three different situations:
1 Inside an item of equipment or enclosure
Where the nominal voltage (U0) within an item of equipment or enclosure exceeds 230 volts (e.g. a non-standard voltage such as 650 V) and where the presence of such a voltage would not normally be expected, before access is gained to a live part, there must be a clearly visible warning of the maximum voltage present.
2 Between simultaneously accessible items of equipment or enclosures
Where simultaneously accessible terminals or other fixed live parts have a nominal voltage (U0) between them which exceeds 230 V (such as where the voltages are from different systems), then a warning notice must be fixed in such a position that anyone, before gaining access to such live parts, is warned of the maximum voltage which exists between those parts.
It would appear that you do not HAVE to apply a warning label but of course you can if you want to!
M
MFHEng
As I said, the reg should refer to fixed equipment, as was it's intent and how it was expected to be perceived , however the actual reg was ambiguous, which is why we may be removing it from the regs in AMD1 .GN1 will be updated accordingly.
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M
MFHEng
"We" would be the IET
Yes this is in the draft for public comment. the regulation will also be changed from 514.10.1 to 514.8.1 and is on page 52/53 of the DPC.
Yes this is in the draft for public comment. the regulation will also be changed from 514.10.1 to 514.8.1 and is on page 52/53 of the DPC.
In what capacity are you the IET?
Wow, senior engineer to the IET, which office do work from? I probably know you!
Hang on, your post has vanished!
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accordfire
So it did. Wonder what caused that....
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MFHEng
Nothing sinister ,just playing with the reply tools. I work out of both
It's good to have a Senior Engineer of the IET here, do you post much on the IET forums?
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MFHEng
don't have too much time to contribute, certainly not as much as we'd like, we may do some kind of faq based on popular posts in the future. Forums are difficult because of the short time you get to post and limited comunication to get your theory and point across.
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eskimo39
Would it not be possible to move them both onto the same phase thus eliminating the 400v across phases?
But is it not the underlying point to help people rather than 'getting YOUR point across' ?
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accordfire
"We"? Are you more than one of you then?
Surely, getting your point across is part of the art of writing in the first place??
Do you moderate the forums over on the IET at all?I know David doesn't get as much time on his own to do the moderating that seems to have been needed of late.
Perhaps, though - if the time was less spent in what amounts to personal attacks, and more on providing advice, guidance, and help that someone of your position should be able to provide, we would all benefit positively?
Just a thought, my £25 worth, you might say.
Yes, I am writing tongue in cheek to a degree.....
M
MFHEng
Point taken, My apologies, would you like a receipt for your £25. We all have off days
The moderating has been the subject of some debate, it is not moderated heavily to promote free will and speach, it is however noted that it gets out of hand from time to time and we don't have time to spend on it at present
As for the underlying help rather than getting your point across, is'nt the point the help. I think "most"(tongue in cheeck) of my postshave been helpfull and not been damning in the way that I have seen others on many forums behave
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accordfire
We do all have off days I guess. Apology accepted, and matter put to rest.
The point is to get the help across, and it's something I think is done rather well here - like you, better than most other forums I have been on or am on. In a short time I've found the guys on here to be the best of a lot of 'em out there, and the regular posters have big hearts and lots of help and care to offer.
And yes - your posts have been helpful too - the regs issues particularly are always good to have clarified, which I guess is really the point of the JELP/64/A committee?
The £25's better in your pocket, as I'm charging too much lol.
M
MFHEng
Thanks Bill, I'm in London today and need it for parking
weve just been snagged for this by the onsite EE,
scenario: potentially the monitor of a pc and the tower could be fed from seperate phases but on the same work station.
M
MFHEng
The scenario is a possibility, however would not cause a problem as the conection between the 2 items would be a signal/data conection and carries no dangerous voltages or currents.
The onsite EE may be getting confused with outside broadcast and entertainment scenarios where there have been fatalities from players of electric guitars where different items of their kit and amplifiers/ mixing decks have had mixed phases introduced, which has unfavourable consequencies .
More prevelent when there is more than 1 generated supply and they are not in parralel. This means that mixed or same phases could come from diferent generators and be not in paralel, which can have serious implications
Roadies are or should be carefull not to mix phases in this type of equipment.(especially with multiple generated supplies on site
For more info look on the forums for someone within this type of field to give a better description but from your point of view, I don't see it as an issue for IT equipment. Even if it where a distance appart and labled, IT and office types would still stretch ex leads arround and ignore any labled warnings.
If your on site EE is still not playing ball email the IET help line with your query and you'll receive an answer to pass to him that may help your cause
I think he's looking at the possibility of 2 items of equipment being in close proximity but being fed from different phases.
The danger would come from a live-earth fault on both items of class 1 equipment resulting in a line-line fault voltage of 400V.
What are the chances of both items of equipment developing such a fault without operating any protective devices?
It's another candidate for that 'myths' thread!
M
MFHEng
I agree, the likely hood would never make a realistic risk assesment, but his on site EE needs to be convinced , as he's the client and paying the invoices. I feel an article title coming on!! "myth busters" .
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darking
the issue I have with this scenario is that someone may isolate one ring at one point, enter the room in question and open a socket believing it to be dead, and become dead himself
If they arn't checking doing a proper safe isolation, then they shouldn't be anywhere near to the socket!
We can't go on with the what if situations forever, we'd never get owt done
Absolutely agree, where do you stop?
If someone opens up a socket then they should be able to confirm isolation.
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darking
We Still need to protect those who may switch off the breaker for one ring, test one socket in the room with a plug tester then treat all the sockets as dead. Remember you also might do a proper isolation on one board and not realise that some of the sockets are being fed by the installation next door. Nothing will show up on the board you have proven dead
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Thats why you would prove dead at the point you are working at. Not just one socket, but every one you work at. Thats why locking of is a good idea too
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