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Author Topic: Pulling power for ONE PA, from two different sources?  (Read 18025 times)

g'bye, Dick Rees

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Re: Pulling power for ONE PA, from two different sources?
« Reply #20 on: June 21, 2014, 04:26:07 pm »

Ok...

Looks like I am renting a Genset...

Thanks guys...(or gals)

Thomas...

You are to be commended for doing it right.  If all goes as it should, the association or some individuals might see their way to defraying your expenses.

Again, congratulations on taking responsibility and the high road.

DR

PS...

I carry liability insurance for my PA work, same amount as you...which is the minimum coverage required around here.  I would not expect it to cover jury rigging power as you proposed. 
« Last Edit: June 21, 2014, 04:43:14 pm by dick rees »
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Jonathan Johnson

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Re: Pulling power for ONE PA, from two different sources?
« Reply #21 on: June 21, 2014, 05:01:37 pm »

Looks like I am renting a Genset...

Just like the HOA is paying the actual costs of the purchase of the fireworks even though the pyros are donating their services (are they professional pyrotechnicians or just pyromaniacs?), so too they should pay your actual costs even though you are donating your services.

If they balk, explain that taking power from two different houses risks equipment damage and they WILL be liable for that. (For some reason, people are more likely to believe "equipment damage" than "electrocution" risk.)

But you DID say they were short on funds, do they plan on passing the hat to make up the difference?

P.S. -- a pyrotechnician is just a pyromaniac with a license. Most firefighters are also pyromaniacs. :)
« Last Edit: June 21, 2014, 05:04:19 pm by Jonathan Johnson »
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Ray Aberle

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Re: Pulling power for ONE PA, from two different sources?
« Reply #22 on: June 21, 2014, 05:52:58 pm »

Just like the HOA is paying the actual costs of the purchase of the fireworks even though the pyros are donating their services (are they professional pyrotechnicians or just pyromaniacs?), so too they should pay your actual costs even though you are donating your services.

Can you source it, spec what's needed, give them the quote and tell them they need to take care of the actual rental? So you're not out money from your pocket, "hoping" that you'll get reimbursed.

You CAN get by with a Honda-series inverter (EU series); don't accept a Home-Depot/Costco styled construction generator. WhisperWatt/trailer-mounted diesel is ideal. 25kW would be more then enough, two spider boxes and 50A twist cabling. Don't forget grounding! (And any local permits that might be required…)

-Ray
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Thomas Metz

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Re: Pulling power for ONE PA, from two different sources?
« Reply #23 on: June 21, 2014, 06:45:41 pm »

It is not the money... well, it is... but it's not....

Last year I spent about $1200 on equipment for my own collection so that I could do the gig W/O equipment from my employer...

I just don't want to start down the "hey Jim I took 4 amps, I will bring them back Monday" road... Just never ends well...

This year, I sold one amp, and purchased 3 more and some other random gear..... (used) down another $1200.

The gear I have purchased is an investment of sorts...

Where as renting a genset,... yep, that is me "throwing money away" OR... I guess now that my production rig has grown large enough... it is "extra insurance"

The pyros, yes, professional. At least the lead guy is. He has another guy or two from his work help out, the rest of his staff are his buddies.

I just called him, and told him the news, he was cool with it, said he would pay out of his pocket for half, and IF if they can not score enough donations between now and the event end to cover the fireworks "and more" he will cover the whole cost... But I doubt that will happen...  so... I only have to pay for half of it...



Ray, I am looking at the Honda EU, for like $100 for one night. I will throw it back in the trees and no one will ever know it is there. It will provide more power than the two 15 amp house circuits can...





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Lyle Williams

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Re: Pulling power for ONE PA, from two different sources?
« Reply #24 on: June 21, 2014, 07:31:12 pm »

Moving on from safety issues, where the cost of mitigation will probably outweigh the cost of a generator...

From an audio perspective, equipment powered from different sources should be expected to be at different ground and electrical potentials.  Audio cables running between different power zones should be transformer isolated and ground lifted.  Don't lift power ground on anything.
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Mike Sokol

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Re: Pulling power for ONE PA, from two different sources?
« Reply #25 on: June 21, 2014, 08:01:42 pm »

Ray, I am looking at the Honda EU, for like $100 for one night. I will throw it back in the trees and no one will ever know it is there. It will provide more power than the two 15 amp house circuits can...

I just saw this thread and agree with the consensus of the swarm. There's simply no upside for going cheap and running extension cords from multiple houses when YOU will be the one in the hotseat if something goes wrong. And the things that can go wrong are both expensive and potentially deadly. I guarantee that the HOA committee will scatter and leave you flapping in the wind if someone gets hurt or somethings blows up. A Honda EU3000 is quiet and makes very clean power.

Just make sure you add a Ground-Neutral bonding plug to the generator (these are floated neutral generators) and pound in a ground rod. But that's another thread...

See http://www.noshockzone.org/generator-ground-neutral-bonding/ for generator GN bonding for RVs. It's the same principal for sound systems except that you should also drive a ground rod and bond it to the generator's chassis/ground lug. 
« Last Edit: June 21, 2014, 08:39:43 pm by Mike Sokol »
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Stephen Swaffer

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Re: Pulling power for ONE PA, from two different sources?
« Reply #26 on: June 22, 2014, 12:15:41 am »

Considering this is an annual event, another option-especially at the $300 price point-depending on the home and panel location you might me able to get a dedicated 20, 30 or 50 A 220 V 4 pole GFCI protected receptacle installed.  An upgrade for the homeowner for letting you use power and a convenience for you next year, too.

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Steve Swaffer

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Re: Pulling power for ONE PA, from two different sources?
« Reply #27 on: June 22, 2014, 06:01:57 am »

From an audio perspective, equipment powered from different sources should be expected to be at different ground and electrical potentials.  Audio cables running between different power zones should be transformer isolated and ground lifted.  Don't lift power ground on anything.

Whilst I'm not suggesting anyone does this, theoretically, what would be the problem with bonding the two grounds together at the equipment end of the cables?  I mean joining the supply grounds, not a link via a signal cable.  Perhaps even with a ground stake at the equipment end too.


Steve.



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Cailen Waddell

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Re: Pulling power for ONE PA, from two different sources?
« Reply #28 on: June 22, 2014, 07:24:42 am »


Whilst I'm not suggesting anyone does this, theoretically, what would be the problem with bonding the two grounds together at the equipment end of the cables?  I mean joining the supply grounds, not a link via a signal cable.  Perhaps even with a ground stake at the equipment end too.


Steve.

I'll take a stab at this.....  And I could be wrong, so please correct me if any of this theory is wrong. 

In a perfect world, with perfect electrical service fed by a common poco transformer to both houses, nothing. It would work fine.

If the houses are fed off of different transformers, while each meters the same, they could be working at different ground/earth potentials with hot leg voltages relative to those.  Tying them together would result in a combined system with two ground neutral bonds, bring both the ground and the neutrals into one ground plane - but relative to which transformer? potentially bringing one house into a n over volt situation and one to an under situation. It could be small, like 110 and 125 or quite large I would suspect.   

Regardless of poco transformer, if a fault condition occurred in either house, and that house had a faulty ground, that fault current could flow up one extension cord and back down the other, at potentially unknown amperages....

Probably more domesday scenarios, but this is what I have thought of so far. 


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Mike Sokol

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Re: Pulling power for ONE PA, from two different sources?
« Reply #29 on: June 22, 2014, 12:49:42 pm »

I'll take a stab at this.....  And I could be wrong, so please correct me if any of this theory is wrong. 

In a perfect world, with perfect electrical service fed by a common poco transformer to both houses, nothing. It would work fine.

If the houses are fed off of different transformers, while each meters the same, they could be working at different ground/earth potentials with hot leg voltages relative to those.  Tying them together would result in a combined system with two ground neutral bonds, bring both the ground and the neutrals into one ground plane - but relative to which transformer? potentially bringing one house into a n over volt situation and one to an under situation. It could be small, like 110 and 125 or quite large I would suspect.   

Regardless of poco transformer, if a fault condition occurred in either house, and that house had a faulty ground, that fault current could flow up one extension cord and back down the other, at potentially unknown amperages....

Probably more domesday scenarios, but this is what I have thought of so far. 


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That's all correct. While there's unlikely to be a large voltage differential between the two houses, the current normalization can be staggering; into the hundreds of amperes. Connecting your extension cords between them will force anything in the middle to pass that amperage, and that's not good for the gear on a lot of levels.

If something really goes wrong at one of the houses (lost neutral to the pole, nearby lightning strike, etc) then your extension cords will be asked to normalize all that voltage as well, which in that case would be considerable and life threatening. And don't even consider bonding the neutrals together as that will cause any GFCI in the path to trip instantly.

A little genny is the way to go. I see those Honda EU3000 inverter generators at small portable stages all the time and they're great. Plus you can run them all weekend on a 5 gal container of gasoline (or petrol for those on the other side of the pond, I think). 
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Mike Sokol
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Re: Pulling power for ONE PA, from two different sources?
« Reply #29 on: June 22, 2014, 12:49:42 pm »


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