Another power distro thread

[Matthew Knischewsky]

Re: Another power distro thread

I have done lots of gigs with 3 phase distros when only single phase power was available. You use a T tap to join two legs and carry on.

This practice is specifically not allowed in Ontario as per document ESA SPEC-003.

4.16 Any single phase power supply shall have its load connectors connected:
a) bond to bond direct connection only; and, b) neutral to neutral direct connection only; and, c) phase to line (Phase A to Line 1, Phase B to Line 2), direct connection only; and, d) any remaining Phase “C” or third line from the load that cannot be supplied directly
from a dedicated power supply line without resort to a Tee fitting or similar device shall be capped off and remain unconnected and unenergized.
A warning label shall be provided as follows:
“WARNING” Phase “C” is not connected and not energized. Single phase source supplies only Phase “A” and “B” of three phase system.



This document is very handy.

http://eesco.ca/wp-content/uploads/2010/12/ESA-SPEC-003-R6.pdf

 

[Rob Timmerman]

Re: Another power distro thread

Wouldn't you overload the conductor that was T'd before you'd overload the neutral, as the neutral is (should be?) sized to take the full current of one leg?

Yes, you would have a neutral imbalance. But it shouldn't be overloaded.

On the feeder side, you will not be able to overload the neutral because you are limited by the overcurrent device protecting your feeders. But on the load side of your distro, you very likely have multiwire branch circuits where two line conductors are in phase with each other. In this case, you have the possibility of neutral current that is double the line current, and likely double the rating of the OCPD.

 

[BJ James]

Re: Another power distro thread

Still undecided here. I'd "like" both racks to be identical, but it's not absolutely necessary. Here's my problem- MOST places I frequent have a range receptacle or 2 for power. Some places have tie-in boxes, and some have boxes for cams. If I make both racks 30a/220v then I always need to carry a small panel with me that would be fed from the range recpt. and then split to 2x L14-30. So, at this point it probably makes most sense to keep the 50a distro, and get a 30A for the second rack. When using the second rack I'd still need the small breakout panel and I would need a 50a to 30a adaptor for the 50a rack. Clear as mud? Just kinda thinking out loud here.
BJ

 

[Tim Weaver]

Re: Another power distro thread

Maybe you need 3 products here. 2 distros that are range plug inlet and are identical. Then a third that is (possibly) 3 phase with cam inlet and 2 range plug outlets. Throw a couple of convenience outlets on it too.

This way when you run across places with 3 phase power you can tie in and still use your range plug connected sub panels. Actually the cool setup might be to have 3 range plug sub panels that are fed from the cam distro. That way you go 3 phase in and split that out to 3 range plugs that have G,N,X,Y / G,N,Y,Z / and G,N,X,Z. That way you are spreading the load over all 3 legs equally.

 

[Jordan Ochocki]

Actually the cool setup might be to have 3 range plug sub panels that are fed from the cam distro. That way you go 3 phase in and split that out to 3 range plugs that have G,N,X,Y / G,N,Y,Z / and G,N,X,Z. That way you are spreading the load over all 3 legs equally.

The only problem I see with this setup is that 3 phase power is 208v between legs, not 240v as range plugs are. Not much issue if you are only powering 120v gear, but it is something to consider.

 

[TJ Cornish]

Re: Another power distro thread

The only problem I see with this setup is that 3 phase power is 208v between legs, not 240v as range plugs are. Not much issue if you are only powering 120v gear, but it is something to consider.

What issue do you see here? Virtually all commercial buildings are 3-phase, and therefore virtually all "single phase" 14-series range plugs in commercial buildings actually provide 208 volts between the two hots. You might get 240 volts at your house, but rarely will you get it at a venue.

You can make an argument that this ~10% voltage difference equals slightly lower power rail voltages for a 240 volt capable amplifier, meaning potentially slightly less deliverable power, but most amps large enough to need voltages higher than 120 are internally regulated and are more dependant on a stiff current supply than the no-load input voltage. And since you can't change the building's supply voltage anyway, you just run with it.

 

[Tim McCulloch]

Re: Another power distro thread

The only problem I see with this setup is that 3 phase power is 208v between legs, not 240v as range plugs are. Not much issue if you are only powering 120v gear, but it is something to consider.

What items in the rig require 240v? If none, this doesn't matter. Since most sound equipment used in the USA is 120v, the 208/120v wye will power it suitably as there is 120v from hot to "neutral."

Some of the new products are happy with any supply voltage between 100v and 250v. While your observation is correct I think your concern is overstated.

Have fun, stay safe.

Tim Mc

 

[BJ James]

Re: Another power distro thread

What about on my existing distro if I changed out one of the 2 30amp 110v twistlocks to a 30a 220v twistlock? And then run a chunk of 8g across to the other rack?

 

[Silas Pradetto]

Re: Another power distro thread

What about on my existing distro if I changed out one of the 2 30amp 110v twistlocks to a 30a 220v twistlock? And then run a chunk of 8g across to the other rack?

You'd have to change them both, since the 240 volt circuit requires a 2-pole breaker, and I doubt that you have additional breaker space in your existing unit. I think the cutout for an L14-30 is larger than for an L5-30, so if you don't mind a little trimming, the rest sounds good!

 

[BJ James]

Re: Another power distro thread

At this point I think I've almost decided to get another pack made that has a 50a CS in with 30A 240V out to my existing rack. I'll simply make an adaptor at the existing rack so I can use the 30a or 50a connector.
Thanks,
BJ

 

[Dale Christenson]

Re: Another power distro thread

Does anyone know where to get a 3U box like this? I want to build one of these, but don't know where to get it.

 

[Jason Dermer]

Re: Another power distro thread

Does anyone know where to get a 3U box like this? I want to build one of these, but don't know where to get it.

Missing a ground? (though it could be tied to the chassis through the input/ output connectors)

Call Motion Labs, they will build you a legal version of this unit in the price range that you are looking for.

 

[Jonathan Betts]

Re: Another power distro thread

Missing a ground? (though it could be tied to the chassis through the input/ output connectors)

Call Motion Labs, they will build you a legal version of this unit in the price range that you are looking for.

This is the inside of the Peavey Distro. The ground wire is hidden under the red wire and is bolted to the frame. I have the same unit and it is a solid distro. Most of the places I work have the 50 amp NEMA 14- 50 receptacle on stage.

 

[Matt Vivlamore]

Re: Another power distro thread

Does anyone know where to get a 3U box like this? I want to build one of these, but don't know where to get it.

Check out Middle Alantic, they have a few blank boxes and you can cut your own holes.
http://www.middleatlantic.com/rackac/chassis/chassis.htm

 

[Josh Millward]

Re: Another power distro thread

Check out Middle Alantic, they have a few blank boxes and you can cut your own holes.http://www.middleatlantic.com/rackac/chassis/chassis.htm

...and by the time you buy a rack mount box, breakers, outlets, punch holes in the box, wire the devices up, and have it ready for use, you will have a perfectly operable distro that has no certification and was built by you.The Peavey Distro, the Amp Shop Distros, the Ramtech Distros, the Motion Labs Distros, and others are all inexpensive in comparison. The parts are not cheap and neither should be your time. Likewise, the liability is worth something also.

 

[BJ James]

Re: Another power distro thread

You'd have to change them both, since the 240 volt circuit requires a 2-pole breaker, and I doubt that you have additional breaker space in your existing unit. I think the cutout for an L14-30 is larger than for an L5-30, so if you don't mind a little trimming, the rest sounds good!

OK, I think I will ust go ahead and order the second pack with 30A I/O. So I will modify my esisting pack this way:
1)Replace 1 L5-30R with a L14-30R on a double pole 30a breaker (2 breaker spaces). This is to supply power to a second rack.
2) Keep 2nd L5-30R for the PL380 amp in that rack - it's on a single pole 30a breaker (1 space)
3) Keep duplex edison on 20a breaker (1 space)
4) Keep duplex edison on 20a breaker (1 space)
5) Keep duplex edison but wire in the orphaned edison that originally had a 20a breaker (1 space). That breaker space was needed for the L14-30R I added in step #1.
That probably sounds confusing the way I wrote it, but to clarify- the pack currently has 6 breakers (2x30 120v, 4x 20 120v), 2 L5-50R, and 4 edison duplex's.
I believe the L14-30R will fit in the existing L5-30R hole.
I may make a small sub panel to make use of the circuits when I'm not using the second rack.
Anyone see any issues here?
Happy Holidays,
BJ