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[Eric_Muller]

Hello,

I always have trouble tripping GFCIs with a certain power distribution box supplied with a local mobile stage. This year I would like to bring my own. I can't seem to pinpoint the proper feeder connector they describe, even people I have asked say it does not exist. The box looks like a typical yellow box, a "Coleman Extreme" for example.

The feeder connection information I have received is...

"ok, below is from the stage guy ...just received....hope this helps!!
50 AMP, 3 PHASE WITH GROUND AND NEUTRAL TWIST LOCK"

and

"The connection at the end of the feeder is:
50 amp
4 wire
3 phase with neutral
It has neutral, phase 1,2,3 and ground"

Thanks,
Eric

[Kyle Van Sandt]

L21-50 does not exist.  It is listed but no one makes it.  The locking part is the real stumper there.  It could be a pin and sleeve.  A pictures are worth a thousand words here...

Odds are though it is a California connector: http://www.lockingpowercords.com/category/31-hubbell-50a-twist-lock.aspx

[Steve M Smith]

"The connection at the end of the feeder is:
50 amp
4 wire
3 phase with neutral
It has neutral, phase 1,2,3 and ground"

Wouldn't that be 5 wires?


Steve.

[Tom Bourke]

4 wire
3 phase with neutral
It has neutral, phase 1,2,3 and ground"

One of these is not like the others.

"It has neutral, phase 1,2,3 and ground" is 5 wires, not 4 as stated.

Here are the configurations available in 50A twist lock.  Notice some are high voltage.
http://www.lockingpowercords.com/category/31-hubbell-50a-twist-lock.aspx

[Kyle Van Sandt]

Wouldn't that be 5 wires?


Steve.

When describing 3 phase systems you never include the ground, a 3 wire system does not have a neutral, a 4 wire system includes a neutral.  Ground is assumed. 

Now, does the guy on the other end of the phone know this... I don't know... but there is no such thing as a 5 wire 3 phase system...

[Tom Bourke]

When describing 3 phase systems you never include the ground, a 3 wire system does not have a neutral, a 4 wire system includes a neutral.  Ground is assumed. 

Now, does the guy on the other end of the phone know this... I don't know... but there is no such thing as a 5 wire 3 phase system...

You can't assume anything.  Household wiring such as romex will be described such as 14-2 with ground or 12-3 with ground.  In that case the ground is not covered to the same extent as the rest and can't be considered for current carrying.  SOOW or similar will be called 12-4.  In that case there are only 4 wires INCLUDING ground. 

In this case the "feeder" should be SOOW or similar and the full conductor count includes ground.  4 wire cable would indicate 2 hot, a neutral and a ground.  If it is 4 wire 3 phase then the ground/neutral are bootleg and that may explain some of the OP GFI problems.

[Shawn Keck]

"The connection at the end of the feeder is:
50 amp
4 wire
3 phase with neutral
It has neutral, phase 1,2,3 and ground"

The 50A CS "California" style connectors are listed on the plug as "125/250v 3P/4W"...which stands for 3 POLE / 4 wire...NOT 3 PHASE!...now there is a 3 phase version of the 50A CS connector bit it will say "250V 3 Phase" and will not have a neutral.

Most likely he confused the 3 pole with 3 phase and what you have is a single phase 50A connector into a jobsite box that breaks out to 6 20A outlets (with a 50A max per leg)

[Eric_Muller]

The 50A CS "California" style connectors are listed on the plug as "125/250v 3P/4W"...which stands for 3 POLE / 4 wire...NOT 3 PHASE!...now there is a 3 phase version of the 50A CS connector bit it will say "250V 3 Phase" and will not have a neutral.

Most likely he confused the 3 pole with 3 phase and what you have is a single phase 50A connector into a jobsite box that breaks out to 6 20A outlets (with a 50A max per leg)

This is what I am ASSuming too. Looks like at this weekend's gig I will be using their distro as I still haven't heard any clarification.

Is there anything I can do to mitigate GFCI tripping?

Usually I take 2 circuits out of the supplied stage distro and plug them into my own 2 x 20 amp distro (foh, monitor, stage power).

Then I run each main speaker group off it's own circuit, fed directly from the supplied stage distro.

I use 4 circuits off their power distro, 2 of them are interconnected, but separately breakered within my own rack distro.

Is it interconnection of circuits via power distro or system interconnection that causes GFCI  tripping? Varying loads amongst the circuits? GFCI age and condition?

The age of the GFCIs is unkown. They do leave the power distro out overnight on the wet field, my recent investigation tells me that is not good for GFCIs. My gear works everywhere else (I can't believe I am the one saying that, lol).

When this distro started tripping last year I kept 1 circuit from my stage and ran 100 ft of 10 gauge cord to another power distro fed from a different feeder in a different location. All power comes from cement ground boxes, no generators. We limped through it fine on 2 circuits, but I wasn't happy.

I have another gig booked here, for that gig I HAVE to bring a bigger system so I will need more power. I will take pictures of the feeder and distro this weekend and post back here. Thanks for the replies.

Eric Muller

[TJ (Tom) Cornish]

This is what I am ASSuming too. Looks like at this weekend's gig I will be using their distro as I still haven't heard any clarification.

Is there anything I can do to mitigate GFCI tripping?

Usually I take 2 circuits out of the supplied stage distro and plug them into my own 2 x 20 amp distro (foh, monitor, stage power).

Then I run each main speaker group off it's own circuit, fed directly from the supplied stage distro.

I use 4 circuits off their power distro, 2 of them are interconnected, but separately breakered within my own rack distro.

Is it interconnection of circuits via power distro or system interconnection that causes GFCI  tripping? Varying loads amongst the circuits? GFCI age and condition?

The age of the GFCIs is unkown. They do leave the power distro out overnight on the wet field, my recent investigation tells me that is not good for GFCIs. My gear works everywhere else (I can't believe I am the one saying that, lol).

When this distro started tripping last year I kept 1 circuit from my stage and ran 100 ft of 10 gauge cord to another power distro fed from a different feeder in a different location. All power comes from cement ground boxes, no generators. We limped through it fine on 2 circuits, but I wasn't happy.

I have another gig booked here, for that gig I HAVE to bring a bigger system so I will need more power. I will take pictures of the feeder and distro this weekend and post back here. Thanks for the replies.

Eric Muller

I'm not exactly clear what you are doing, but if you are trying to combine two circuits to feed an L14-30 or something, that will definitely not work from GFCI circuits, and really isn't OK anyway.

GFCIs can potentially go bad, it is also possible that you have something leaky in your rig that you aren't aware of.  What happens when you measure continuity (devices unplugged of course) from ground to neutral of male plug end of each of your loads - i.e. unplug the cord from the distro and probe hot to ground on the male plug?  the resistance is less than 40K ohms, that means you have 3ma of leakage current.  If the number is somewhat higher but you plug several power strips into the same circuit, the leakage is cumulative.

[Stephen Swaffer]

It is not clear where the GFCIs are located?  If neutrals are shared/parallel/connected to each other or to ground anywhere after the GFCIs you will have trouble with tripping.  Basically, the hot wire from the GFCI and the neutral from that GFCI must be connected to the same loads and ONLY to those loads.  If that is the case, then as Tom said you may have leakage in equipment, but I would think that should show up at other locations (unless there is a possibility of getting moisture in your equipment overnight here and never anywhere else?)

FWIW, newer GFCIs are "supposed" to reset only if they are working right-not knowing the age it would be hard to tell if this is the case. 

[ProSoundWeb Community]