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[Josh Evangelista]

Hi guys,

Im in California and mostly do small to medium EDM shows. I own:

2 Powersoft K20s
2 Powersoft X4s

with a possible third K20 added to this list.

I was wondering what kind of distro inlet and breakout config should I go to? Im thinking of a California 50A in to four L5-30s. However, I was browsing the Motion Labs RacPac page and I mostly saw L21-30 inlets with breakout L5-30s. There are also L14-30s. I plan to make adapters for 5-20R just in case for smaller shows.

Thanks.

Josh

[Mark Cadwallader]

The inlet is dependent on what you have available as the power supply. An L21 series plug is for three phase power - three hots, a neutral, and ground at 120 and 208. A CS63xx is 120/240 with two hots, a neutral, and a ground. An L14 is also 120/240 with two hots, a neutral, and a ground.  A 14-50P is a straight blade "stove plug", and is rated for 50 amps like a CS63xx series; a 14-30P is a straight blade "dryer plug".

A 14-30P to a CS63xx inlet adapter is OK, but not a CS63xx to 14-30R or L14-30R.

Figure out what your venues (mostly) have for recepticles, and go from there b

[Ben Mehlman]

There are several issues here.

The first being that a three phase distro can be harder to balance the load on (you want equal load on all phases.. as reasonably close as you can), and the consequences of unbalancing it are greater.. because any current that is not balanced out flows through the neutral.. and if your neutral is the same size as your hots, you could run out of neutral capacity and potentially overheat your cable.  There are cables with oversized neutrals tho, which helps smooth out lots of issues.

A single phase distro is a little easier because there's more neutral copper in relation to hot leg copper when they're all the same size, so you can handle more neutral current.  The down side is that when you are tying your two legs into a three phase source, you're already running neutral current even when your load is perfectly balanced on the two legs, because your legs are only 120 degrees apart, phase wise, not the 180 they would be if they were on a single phase source.

For me.. I decided a single phase made more sense.. less conductors, more copper per conductor.. more forgiving of various hookups.  I had chosen a CS tie-in in the past and liked it, in a system that I built but didn't own.. so when I built my system I looked to go the same way.. but due to cost I went for a 60 amp setup with L14/30.. I have a lower wattage system than you.. but  basically, I've had no problems going into three phase panels.  Usually the panels are no less than 100A (per leg) and usually more.. so don't mind my uneven loading.

In short, I'm more worried about my neutral's capacity than theirs, that's why I went single phase.  And a CS gives you 100A whereas an L21 gives you 90A (if everything is balanced perfectly).

But obviously a lot of people disagree with me, based on the popularity of L21/30 distros.

When I used to do stage lighting in the age of massive dimmer racks, I always went three phase, it would be crazy not to.  But those loads were big and easy to balance.  I'm not convinced that relatively small numbers of amp loads balance well enough unless you have got things in threes, eg three/six sub amps.. or if you have a lot of racks and things start to average out.

[Stephen Swaffer]

There are several issues here.

The first being that a three phase distro can be harder to balance the load on (you want equal load on all phases.. as reasonably close as you can), and the consequences of unbalancing it are greater.. because any current that is not balanced out flows through the neutral.. and if your neutral is the same size as your hots, you could run out of neutral capacity and potentially overheat your cable.  There are cables with oversized neutrals tho, which helps smooth out lots of issues.

A single phase distro is a little easier because there's more neutral copper in relation to hot leg copper when they're all the same size, so you can handle more neutral current.  The down side is that when you are tying your two legs into a three phase source, you're already running neutral current even when your load is perfectly balanced on the two legs, because your legs are only 120 degrees apart, phase wise, not the 180 they would be if they were on a single phase source.

From a distro standpoint, phase balancing is not make or break.  Yes, ideally you balance the loads- but unless you have high harmonic loads, it is impossible to overload a full size ( not oversized) neutral on a properly designed distro just by unbalancing.  The high harmonic loads can be a problem even if perfectly balanced.

Running a single phase off a 3 phase source, likewise will not overload a neutral. 

Most buildings are built with reduced size neutrals because the neutral only has to carry the unbalanced load.  Most distro's are designed with a full size neutral, so you already have a bit of a safety factor there.

As was suggested, match your distro to the venues you use. If a mix of 3 phase and single/split phase, IMO, its easier to run with a single phase distro all of the time.

If you are using a 30 amp distro on a 50 a receptacle, you have to have overcurrent protection- which is why you won't find commercial breakouts going from a 50 amp plug to a 30.  Likewise, adapters for 5-15s and 5-20s allowing them to be supplied by a 30 amp circuit need to provide overcurrent protection ( usually breakers).

[Josh Evangelista]

Thank you guys.

So if I configure four L5-30s, which inlet is best, an L14-30 or a CS/50a?

[Frank Koenig]

Hi guys,

Im in California and mostly do small to medium EDM shows. I own:

2 Powersoft K20s
2 Powersoft X4s

with a possible third K20 added to this list.

I was wondering what kind of distro inlet and breakout config should I go to? Im thinking of a California 50A in to four L5-30s. However, I was browsing the Motion Labs RacPac page and I mostly saw L21-30 inlets with breakout L5-30s. There are also L14-30s. I plan to make adapters for 5-20R just in case for smaller shows.

Thanks.

Josh

I can't tell you what size distro you need but one thing to keep in mind is that if 30 A is sufficient it will save lots of weight (and cost) in cables. L-14-30 is popular around here for feeding power amps and my system is all L-14-30. I do own a construction-style spider box with 50 A in and through that has two L-14-30 receptacles (on 30 A breakers), should I need to run from a generator or other 50 A source. I also have a 5-15 to L-14-30 adapter cord (legs tied together) that lets me use the same distro components on 120 V for low power gigs. All my loads are wired for 120 V operation to allow this.

--Frank

[Mike Sokol]

The first being that a three phase distro can be harder to balance the load on (you want equal load on all phases.. as reasonably close as you can), and the consequences of unbalancing it are greater.. because any current that is not balanced out flows through the neutral.. and if your neutral is the same size as your hots, you could run out of neutral capacity and potentially overheat your cable.  There are cables with oversized neutrals tho, which helps smooth out lots of issues.

That's not exactly correct. In a split-phase system the two legs are 180 degrees out of phase, and currents ending up on the neutral are 100% subtractive. In a 3-phase power system each of the legs are 120 degree offset, so the neutral currents aren't 100% subtractive. But you'll still never get more current on the neutral than any single leg.   

What you're probably referring to are triplen currents, which are the result of odd-harmonic currents from switching power supplies and Triac light dimmers. And you can't balance the loads to reduce triplen currents. In that case you can easily create more current on the neutral than any single leg, which can burn up neutrals and their connectors. And that's why double and oversize neutrals are often used in 3-phase systems.

[TJ (Tom) Cornish]

Hi guys,

Im in California and mostly do small to medium EDM shows. I own:

2 Powersoft K20s
2 Powersoft X4s

with a possible third K20 added to this list.

I was wondering what kind of distro inlet and breakout config should I go to? Im thinking of a California 50A in to four L5-30s. However, I was browsing the Motion Labs RacPac page and I mostly saw L21-30 inlets with breakout L5-30s. There are also L14-30s. I plan to make adapters for 5-20R just in case for smaller shows.

Thanks.

Josh

If you are considering any kind of distro, it makes sense to run as much stuff at 208v/240v as possible.  L5-30 connectors are IMO the wrong things to build your distro around.  Your Powersoft amps have universal power supplies and can handle 208/240v.  This has several advantages - your amp will be happier, you can get the same power on less wire, and for these devices you're not using the neutral conductor at all, so no issues with neutral wire overload.

I personally like distros based around L14-20 devices.  This is a very flexible size that requires no downstream branch circuit breakers, unlike the 30 amp systems which need further overcurrent protection to break them down to 20A circuits (and not evenly either - 30A isn't really enough to get 2 full 20A circuits out).  The L14-20 system provides with just wiring changes 2 20A 120v circuits or 1 20A 208/240v circuit.  This is wired using 12/4 SOOW cable (or even 12/3 SOOW if you're not using the neutral wire), whereas the 30A systems require #10 wire for the 14-30 system and #8 wire for the 21-30 system.

If it were me, I'd get a RackPack with a 50A California inlet and L14-20 receptacles for your amps.  Both MotionLabs and Whirlwind can build this for you.

I wrote an article about this a while ago that may be helpful to you.
http://tjcornish.com/articles/power-and-electricity-artic/power-distribution-part-3--.html

[Josh Evangelista]

I can't tell you what size distro you need but one thing to keep in mind is that if 30 A is sufficient it will save lots of weight (and cost) in cables. L-14-30 is popular around here for feeding power amps and my system is all L-14-30. I do own a construction-style spider box with 50 A in and through that has two L-14-30 receptacles (on 30 A breakers), should I need to run from a generator or other 50 A source. I also have a 5-15 to L-14-30 adapter cord (legs tied together) that lets me use the same distro components on 120 V for low power gigs. All my loads are wired for 120 V operation to allow this.

--Frank

Hi Frank. What I dont understand is why does Motion Labs makes more distros with default inlets of L21-30s rather than L14-30s. I also plan to make my own 5-15 to L-14-30s and 5-20 to L14-30s.

[Josh Evangelista]

If you are considering any kind of distro, it makes sense to run as much stuff at 208v/240v as possible.  L5-30 connectors are IMO the wrong things to build your distro around.  Your Powersoft amps have universal power supplies and can handle 208/240v.  This has several advantages - your amp will be happier, you can get the same power on less wire, and for these devices you're not using the neutral conductor at all, so no issues with neutral wire overload.

I personally like distros based around L14-20 devices.  This is a very flexible size that requires no downstream branch circuit breakers, unlike the 30 amp systems which need further overcurrent protection to break them down to 20A circuits (and not evenly either - 30A isn't really enough to get 2 full 20A circuits out).  The L14-20 system provides with just wiring changes 2 20A 120v circuits or 1 20A 208/240v circuit.  This is wired using 12/4 SOOW cable (or even 12/3 SOOW if you're not using the neutral wire), whereas the 30A systems require #10 wire for the 14-30 system and #8 wire for the 21-30 system.

If it were me, I'd get a RackPack with a 50A California inlet and L14-20 receptacles for your amps.  Both MotionLabs and Whirlwind can build this for you.

I wrote an article about this a while ago that may be helpful to you.
http://tjcornish.com/articles/power-and-electricity-artic/power-distribution-part-3--.html

Hi Tom. I have read your page several times in the past and have bookmarked it. Thank you for your articles as it explains everything in detail, kinda like a dummies book for me to be honest.

Anyway I like your suggestion to just stick to a 50A CS inlet in your page. However, the breakout L14-20s might be short for what I will be doing 6-%-70% of the time. I do EDM shows and most likely will use about 1/3 power amp ratings so looking at the amp's power draw specs, I might run into 25amps on 230v so I think I will keep the L14-30s just so I am ready. I carry Void Acoustics.

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