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Author Topic: Just a reminder to check the power at your distro as well as the wall.  (Read 3386 times)

Steve M Smith

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #30 on: January 27, 2014, 04:59:27 pm »

The potential that I see -- especially in higher-amperage connections -- is that someone would connect or disconnect the multipin power connector while the facility connection is energized and there is a load on the distro. That could result in a significant arc flash explosion.

These are usually arranged so that the switch also locks the plug in place.  The last time I connected one up in a venue, this was the case.

The photo I linked to earlier was a panel mount type which would be part of your own distribution.  The venue's supply would have something like this:



With this, you can only plug it in or remove it if the switch is off.  You can't even open the cover unless the switch is off.


Steve.
« Last Edit: January 27, 2014, 05:04:10 pm by Steve M Smith »
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Ray Aberle

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #31 on: January 27, 2014, 05:42:20 pm »

These are usually arranged so that the switch also locks the plug in place.  The last time I connected one up in a venue, this was the case.

The photo I linked to earlier was a panel mount type which would be part of your own distribution.  The venue's supply would have something like this:



With this, you can only plug it in or remove it if the switch is off.  You can't even open the cover unless the switch is off.


Steve.
That's a good setup. Cams are not rated for interrupting current either, so same deal, you need to make sure the source is de-energized before connecting/removing the cables. And even still, ground (then neutral) connects first and removes last!

Ray
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Tom Bourke

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #32 on: January 27, 2014, 05:43:49 pm »

These are usually arranged so that the switch also locks the plug in place.  The last time I connected one up in a venue, this was the case.

The photo I linked to earlier was a panel mount type which would be part of your own distribution.  The venue's supply would have something like this:



With this, you can only plug it in or remove it if the switch is off.  You can't even open the cover unless the switch is off.


Steve.
Do you still check your power with all these safety features?  I would think a lose or miswire is still possible. 
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Jonathan Johnson

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #33 on: January 27, 2014, 06:31:27 pm »

Do you still check your power with all these safety features?
Always inspect your safety features, test them where applicable, but never trust them.
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Stephen Swaffer

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #34 on: January 27, 2014, 09:32:17 pm »

Might be worth noting that in the example posted by Mike under arc flash, one of the serious violations cited by OSHA was failure to ensure that it was safe to apply power BEFORE energizing the circuit.   Certainly a missing ground and/or neutral would make it unsafe.  Just one more entity to encourage testing!

When I install a high energy circuit-a judgement call, but usually 60 A or greater-in an industrial situation, I usually use a megger/insulation tester to check for shorts to ground.  It is a quick test to make sure you don't energize a dead short and tempt a breaker to explode in your hand.  Just make sure with A/V stuff you are only testing distro and not equipment!
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Steve Swaffer

Steve M Smith

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #35 on: January 28, 2014, 01:52:06 am »

Do you still check your power with all these safety features?  I would think a lose or miswire is still possible.

Yes, but obviously, a safety feature at the outlet doesn't prevent a problem further down the line.

A loose wire is possible whatever connectors you use but a hard wired plug isn't going to re-arrange itself in the way a set of single pole connectors could be miswired with just a colour code as a 'safety feature'.

And even still, ground (then neutral) connects first and removes last!

Every power connector in the UK, domestic or industrial, has the ground pin longer than the others so it always connects first and disconnects last.


Steve.
« Last Edit: January 28, 2014, 01:55:05 am by Steve M Smith »
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Tom Bourke

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #36 on: January 28, 2014, 02:24:10 am »

Yes, but obviously, a safety feature at the outlet doesn't prevent a problem further down the line.

A loose wire is possible whatever connectors you use but a hard wired plug isn't going to re-arrange itself in the way a set of single pole connectors could be miswired with just a colour code as a 'safety feature'.

Every power connector in the UK, domestic or industrial, has the ground pin longer than the others so it always connects first and disconnects last.


Steve.
The reason I ask is that these threads tend to turn into comparisons to how much better or simpler power distribution is in Europe.  Often times implying “We couldn't possible have that problem here.” While I admit I envy the simpler standards, I think the main problems are the same.  I see far more problems from abuse and poor maintenance than confusion over plug type.  I am pretty sure bad maintenance happens, or dose not happen, on both sides of the pond.  Do you also have venues using odd or misusing connectors in an attempt to force you to buy power from them?
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Steve M Smith

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #37 on: January 28, 2014, 02:46:05 am »

Do you also have venues using odd or misusing connectors in an attempt to force you to buy power from them?

Buy power?  No.  We just turn up and plug in.

In the US you seem to have a lot of connectors to choose from.  Over here, it is very standardised.  Domestically, you will only find one type of outlet, the 13A socket, unless it is in a house which hasn't been upgraded in the last sixty years.  And in commercial and entertainment venues, you will always find the outlet I showed above.  These come in 32A, 63A (why not 64?) and 125A versions.

So yes, I think the siuation is better here.  Not in a smug "we're better than you" way but because you are in a bigger country which has had a lot more standards with regards to power connections over the years and your country tends to work with rules issued state by state whereas ours affect the country as a whole.

Standards of maintenance and attitudes to its importance are more to do with human nature than anything else and I'm sure we have our fair share of people whose standards are not good enough.


Steve.
« Last Edit: January 28, 2014, 02:49:40 am by Steve M Smith »
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Ray Aberle

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #38 on: January 28, 2014, 11:28:13 am »

Buy power?  No.  We just turn up and plug in.

Steve.
Mostly hotels, but some venues, will utilize a specific wall outlet type (l5-15 or -20 are common), requiring renters to get the right adapter from the venue. By this method, the venue knows if you are using their power, and charges accordingly.

Even if there is no strange adapter, hotels will often charge for cam access. Another source of revenue, as it will make the general room charge seem smaller?

Ray
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Jonathan Johnson

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Re: Just a reminder to check the power at your distro as well as the wall.
« Reply #39 on: January 28, 2014, 06:40:37 pm »

A loose wire is possible whatever connectors you use but a hard wired plug isn't going to re-arrange itself in the way a set of single pole connectors could be miswired with just a colour code as a 'safety feature'.

Such as might occur in a low-light or colored-light situation. Under green lights, red and black will be difficult to distinguish, as will green and white. Under red light, it's green/black and red/white -- a potentially more dangerous mixup. Under other colors, it could be any kind of mixup. Bottom line:  only make connections under white light that is sufficient to do the job safely.
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