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Plugging into 400 Volt socket


Kevsy71
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Have just set up for tonight's gig, in a pub barn next to the carvery. The sockets there are all labelled 400 Volt, which IIRC is a 3-phase supply for industrial heaters. Throwing caution to the wind we plugged in to them with our 230 v equipment, and it all seems to work. I'm hoping that is because it does not deliver 400 volts all the time, rather it can just peak at that. Is that right?

Cheers!

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[quote name='Kevsy71' timestamp='1415459933' post='2600592']
Have just set up for tonight's gig, in a pub barn next to the carvery. The sockets there are all labelled 400 Volt, which IIRC is a 3-phase supply for industrial heaters. Throwing caution to the wind we plugged in to them with our 230 v equipment, and it all seems to work. I'm hoping that is because it does not deliver 400 volts all the time, rather it can just peak at that. Is that right?

Cheers!
[/quote]

It's not physically possible to plug a UK mains plug into a 3-phase socket, so it can't be that. I'd guess that, if it worked with no smoke, that, firstly, you were very lucky and extremely foolish to even think of doing such a thing (someone could get killed if you'd got it wrong..!), secondly, that the 400v refers to the maximum voltage reached by ordinary UK mains 220v at the peak of its 50Hz cycle. The rms value is 220, but the insulation (wires, cables etc...) must be able to withstand the full 400v. Nothing to do with industrial heaters, I wouldn't think, and can see no reason to label ordinary mains sockets in that way. Others may have an explanation for that.

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The sockets are coming off of a three phase distribution board.
The electrician has labelled the sockets as 400v because there [b]is[/b] a 400v potential there, not because there's 400v coming out of the socket. :).

If there [b]was[/b] 400v being delivered then you'd be asking 'can anyone lend me a PA for tonight?'. :D

EDIT: Not a 100% accurate way of judging things, but if the installer has gone to the trouble of labelling the sockets (as per regs if you follow them to the nth degree) then there's a good chance that it wasn't a DIY job.

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It could be the label is indicating that there is 400v between the sockets as they are on different phases.
They should not then be within arms reach (no less than 6 feet) of each other but long leads throws all that out of the window.
Just make sure your own equipment is up to scratch as any problems will have a greater effect.
You could lessen any problem by plugging everything in to one socket but then that will be down to the load you are drawing.

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Just be a little carefull maybe best to use only one socket for PA and the back line in case he has wired each socket from a different phase, this could then be dangerous if you have a fault to earth or a loose neutral if playing and singing with your bass rig on one phase and the PA on another, It won't be a tingle on the lips from the mic it will be bang and the smoke from your ears may be terminal. :(

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[quote name='goingdownslow' timestamp='1415465204' post='2600655']
It could be the label is indicating that there is 400v between the sockets as they are on different phases.[/quote]

Yep, that's the one. :)

It'd help if the labels were a little clearer about what they were trying to convey, but the most instructive 'off the shelf' one that I found when I needed some was just 'Danger 400v'.

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On a related safety note, I've had some real nasties over the years so before we plug [b]anything[/b] in we use a mains tester plug to ensure the socket is both earthed and wired correctly.

All of our extension leads are fitted with RCD plugs before they get anywhere near a gig.

Suspect leads are marked with red tape and not used again until I've both electrically and visually checked them, and I'll always make them unusable and bin them rather than rely on 'it's near enough'.

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Yep, wise precautions. I carry one of those plug-in mains testers in my gig bag and I try to ensure everything is connected to a single mains socket, albeit through loads of plug-blocks.

I can understand a large venue requiring sockets fed from different phases, but I'd be a bit surprised if different phase sockets were mixed very closely together. Better to confine different phases to different areas whenever possible.

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[quote name='flyfisher' timestamp='1415468865' post='2600713']
I can understand a large venue requiring sockets fed from different phases, but I'd be a bit surprised if different phase sockets were mixed very closely together. Better to confine different phases to different areas whenever possible.
[/quote]

It really depends on what you're trying to achieve, having different phase supplies near each other can be advantageous [b]if[/b] used sensibly.

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[quote name='Kevsy71' timestamp='1415459933' post='2600592']
The sockets there are all labelled 400 Volt, which IIRC is a 3-phase supply for industrial heaters. Throwing caution to the wind we plugged in to them with our 230 v equipment, and it all seems to work.
[/quote]

Honestly, that made me gasp.

It should have read 'taking our lives in our hands we plugged in and...'

For your own sakes, please be more cautious next time.

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[quote name='icastle' timestamp='1415470231' post='2600728']
It really depends on what you're trying to achieve, having different phase supplies near each other can be advantageous [b]if[/b] used sensibly.
[/quote]

IF indeed - which is unlikely in what is probably a public venue.

How many jobbing bands have qualified electricians setting up their gear for them? How many people would understand what precautions to take when using sockets labelled '400V'? How many people would just plug in anyway and hope?

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[quote name='flyfisher' timestamp='1415486647' post='2600916']
How many jobbing bands have qualified electricians setting up their gear for them? How many people would understand what precautions to take when using sockets labelled '400V'? How many people would just plug in anyway and hope?
[/quote]

It's a bit of a moot point really.

It is unusual to find adjacent feeds from a three phase distribution board in venues that most of us perform in.

They're generally only adjacent if there is a specific need for them to be so, and the areas where that would be the case are generally not areas you'd be performing in.

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[quote name='planer' timestamp='1415480761' post='2600853']
Honestly, that made me gasp.

It should have read 'taking our lives in our hands we plugged in and...'

For your own sakes, please be more cautious next time.
[/quote]

Yes - really stupid, and no excuse. The lesson I've learnt here is always check the venue beforehand where feasible (and this was, it's local) then I could have had this checked out beforehand and no worries on the night.

My electrician friend tested and confirmed they were regular, working 3-pin 13 amp sockets, but of course we should have done that before flicking the switch. Nobody at the venue knew why they were labelled with the warning. It's possible it was to make more visible the warning of the big heater socket which was next to them, but that's a guess.

[quote name='flyfisher' timestamp='1415486647' post='2600916']
IF indeed - which is unlikely in what is probably a public venue.

How many jobbing bands have qualified electricians setting up their gear for them? How many people would understand what precautions to take when using sockets labelled '400V'? How many people would just plug in anyway and hope?
[/quote]

Certainly I will from now on, regardless of peer pressure or time constraints or even if 'it's a fundraiser, we don't want to let them down' etc.

Anyways a big thank you to everyone for replying to this so quickly on a Saturday night, and for slapping some sense into me! Won't happen again :blink:

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I would say the stickers are there not because of potential between sockets in that area as any property with 3 phase has that potential especially once an extension lead is introduced but more likely that the wiring for another ring main on another phase is contained within the socket box. Most industrial installations are done that way rather than running three conduits all the wires run down one so when you remove a socket face you are exposed to all three phases.

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[quote name='goingdownslow' timestamp='1415465204' post='2600655']
It could be the label is indicating that there is 400v between the sockets as they are on different phases.
They should not then be within arms reach (no less than 6 feet) of each other but long leads throws all that out of the window.
Just make sure your own equipment is up to scratch as any problems will have a greater effect.
You could lessen any problem by plugging [u][i][size=5][b]everything in to one socket[/b][/size][/i][/u] but then that will be down to the load you are drawing.
[/quote]

This.

The tought of having a bands kit wired on different phases is just too scary.

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[quote name='icastle' timestamp='1415500513' post='2600994']
It's a bit of a moot point really.

It is unusual to find adjacent feeds from a three phase distribution board in venues that most of us perform in.

They're generally only adjacent if there is a specific need for them to be so, and the areas where that would be the case are generally not areas you'd be performing in.
[/quote]

Yes, but 'unusual' and 'generally' suggest that it's not really a moot point . . . . as the existence of this thread attests.

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[quote name='stingrayPete1977' timestamp='1415534034' post='2601180']
I would say the stickers are there not because of potential between sockets in that area as any property with 3 phase has that potential especially once an extension lead is introduced but more likely that the wiring for another ring main on another phase is contained within the socket box. Most industrial installations are done that way rather than running three conduits all the wires run down one so when you remove a socket face you are exposed to all three phases.
[/quote]

That makes sense, but do the regulations require that sockets/conduit containing three phases have such warning labels? After all, it's not exactly 'normal use' for someone to open up a socket so if the normal users of such sockets cannot be exposed to three phases by simply plugging in a standard plug why bother with warning labels at all. After all, by definition, it's only qualified electricians who can be expected to properly understand what such labels actually mean in practice.

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