Edison to 3 Phase

[Lazerlight]

Recently on a job, the company I was working with had an adapter for when there was no 3 phase for their amp rack. It was 3 edison plugs one one end and a 3 phase twist lock on the other end. The plugs plugged into 3 separate circuits and the 3 phase adapter went to there amp rack. I was wondering if someone could give me a wiring diagram as to how this adapter is wired together as well as how the amps are connected in a 3 phase amp rack.

Thanks.

 

[JCarroll]

I personally believe that if this is something you have to ask about, you really shouldn't be making. This is a dangerous adapter in the wrong untrained hands, and really shouldn't be kept around...

 

[Lazerlight]

I don't plan on making one, I just want to know more about them.

 

[Footer]

Ya, no. There are so many things that are both illegal and unsafe about that type of adapter.

Sent from my Nexus 7 using Tapatalk HD

 

[cmckeeman]

Is this what you are talking about

 

[Les]

Yeah, I think this is along the lines of "here's how you make a bomb..."

 

[danTt]

cmckeeman: Except it goes the other way.

JCarroll: I personally believe that even if you don't have to ask about it, this is not something you should be making. It's illegal, dangerous, and just asking to cause an injury or worse.

Lazerlight: Sometimes in the industry, companies feel pressured to do dumb things. I strongly encourage you to avoid companies that make this a common practice. I know that sometimes it's difficult to do, especially given the area you are working it, but don't allow yourself to be in a position where your actions could result in the injury of others (or more importantly, yourself). I suggest reading about 3 phase WYE power on wikipedia, and on the google, and that should give you the theoretical background to understand not only why a 3 Edison to 21-30 (or similar) adaptor is possible, but also why it's a dangerous and entirely stupid idea (that could result in anywhere from 120volts, to 208 volts, to 240 volts based on where you plug it in...)

 

[cmckeeman]

cmckeeman: Except it goes the other way.

i wouldn't touch that with a 10 ft stick

 

[derekleffew]

I was wondering if someone could give me a wiring diagram as to how this adapter is wired together...

Sorry, no. You COULD buy one of these (except it seems to be no longer listed on Lex Products' site) and change all the genders.

Furthering what's been said, note that products exist to go from one 3Ø to three 1Ø outlets:
(one example)

PowerFLEX™ Cable Assemblies: 3Phase 3Fer | Lex Products

but NOT the reverse (not legally, at least).

If one were so inclined, one could likely find pictures at various "wall of shame" sites. Pictures depicting bad, illegal, or unsafe practices are frowned upon here at ControlBooth.

-----

... as well as how the amps are connected in a 3 phase amp rack.

The rack probably contains three 120V amplifiers. Each uses one full HOT leg alone, and shares 1/3 of the common NEUTRAL with the other two amps. The NEMA L21 series connectors are labeled 120/208Y (Wye) as they can provide both 120V or 208V, depending on which poles are connected.

In North America, very few amplifiers operate at anything other than 120V. But here's a notable exception: Vrack Complete Amplification System

Run 120VAC or 208VAC (US) or 220VAC to 240VAC (international) with the flip of a switch

 

[sk8rsdad]

i wouldn't touch that with a 10 ft stick

I would. Repeatedly. Preferably with a non-conductive stick. Until either it or the stick was broken.

 

[JD]

Summary adapters are out there in people's toolboxes, but they are a very bad idea!
Here are some of the reasons you should not use them:

1) On CGFI protected circuits, they will fail to work and will trip the protection often before you even connect a load.

2) They allow for dangerous neutral cross currents to occur in building wiring, which in the worst case may cause a fire. This is especially true if you happen to pick two outlets that are fed by separate load panels.

3) The common neutral in the three phase cable may end up running at 300% of rated capacity if all three hots end up on the same phase.

4) and maybe the most important- They are illegal with regard to any code and you will be shut down if inspected.

 

[markviml]

Instead, you could unplug the amps from the distro in the rack and plug them directly to individual wall outlet. They may need to be on individual breakers depending on what the amps are pulling.

 

[Footer]

Summary adapters are out there in people's toolboxes, but they are a very bad idea!
Here are some of the reasons you should not use them:

1) On CGFI protected circuits, they will fail to work and will trip the protection often before you even connect a load.

2) They allow for dangerous neutral cross currents to occur in building wiring, which in the worst case may cause a fire. This is especially true if you happen to pick two outlets that are fed by separate load panels.

3) The common neutral in the three phase cable may end up running at 300% of rated capacity if all three hots end up on the same phase.

4) and maybe the most important- They are illegal with regard to any code and you will be shut down if inspected.

Finally, because the breakers are not bonded, if one leg has a fault the other two legs will remain hot...

 

[n1ist]

Finally, because the breakers are not bonded, if one leg has a fault the other two legs will remain hot...

Worse, if you unplug one of the plugs while the load is still connected, you will end up with live prongs in your hand. A sure-fire way to kill someone.

The only safe way to make one includes multiple relays and phase-rotation sensors. It's NOT worth risking death or fire. Have a proper receptacle installed.
/mike