[RE-wrenches] 480 Wye or Delta for a SolarEdge 10K 3-phase; how can I determine what this panel is?

Tue Dec 16 08:25:47 PST 2014

Hi:

Grounding, (they use the term earthing in the IEC/Euro world), variations 
like this are not very common in North America as we overwhelmingly use a 
TT method which means there is a dedicated ground rod at the building.

In many other parts of the world power lines are underground and so the 
systems use different grounding/earthing methods.

These methods are classed as TT, TN, TN-C, TN-C-S, and so on.......

From your explanation, I think this new building uses a variation of 
TN-C-S, (T is GND, N is neutral, the C-S means single combined Neutral/GND 
wire to the building which separates at the service entrance).

You can find a lot of info on the net, but here is an explanation from the 
IEC rules regarding TN-C-S grounding/earthing.

480/277 are the right voltages for a 480WYE.

Since its been done, there must be some applicable North American codes 
somewhere.

JARMO

_____________________________________________________________________________________ 

Jarmo Venalainen  |   Schneider Electric   |  Solar Business  |   CANADA | 
  Training & Development Specialist - Senior 
Phone: +604-422-2528  |   Fax: +604-420-1591  |   Mobile: +604-505-0291 
Email: jarmo.venalainen at schneider-electric.com  |   Site: www.SEsolar.com 
|   Address: 3700 Gilmore Way, Burnaby, BC V5G4M1 

*** Please consider the environment before printing this e-mail 

From:
"Howard \"Scot\" Arey" <scot.arey at solarcentex.com>
To:
<re-wrenches at lists.re-wrenches.org>, 
Date:
12/15/2014 05:50 PM
Subject:
[RE-wrenches] 480 Wye or Delta for a SolarEdge 10K 3-phase;     how can I 
determine what this panel is?
Sent by:
"RE-wrenches" <re-wrenches-bounces at lists.re-wrenches.org>

My challenge is determining the correct 480V configuration so I can use a 
3-phase Solar Edge 10000 for a 12KW commercial system.  The SE10K requires 
a 480V Wye configuration.

The main 480 panel looks straightforward.  L1, L2, L3 come from below 
grade to three separate busbars in the panel.  A 4th wire, not taped 
white, goes to what appears to be a ground bar at the lower right of the 
panel.  Green and green-taped wires come from this bar. I do not see any 
physical connections between the L1, L2, L3 bus bars and the ground bar in 
the lower right, other than the box itself as the ground bar appears to be 
bonded to the main box itself.

Voltage measurements depicts 480V at line to line, and 277 Volts from each 
line to the ground (neutral?).

The overhead service at the road depicts 4 wires into the service head. 
The three from the three each transformers at the pole are taped 
traditional 3-phase colors.  The bare wire from the pole to the service 
head is bare wire, but is taped white as it goes into the service head 
with an insulated conductor (wire).  There is no apparent ground wire at 
the pole or inside the building that I can see but the service is 
underground and under concrete until it comes up inside the facility at 
the 480 panel board.

My master electrician is researching to determine the type but I wanted to 
post it here for comments, too.

My questions:
-          Is it possible to have an ungrounded Wye where the “4th wire” 
actually is a neutral to the lower right bus bar, and the wires leaving 
that bar are in fact ground wires?
-          The SE10K calls for a neutral wire in a Wye config.  If this 4
th wire is a neutral, and is bonded to ground, can I run a wire from this 
to the inverter neutral, then another wire from this same bar t0 other 
ground wire location in the SE10K (right beside the neutral).
-          Is the white taped wire (the bare wire from the pole, then 
insulated and taped white into the service head) a neutral or is that 
ground.
-          Can anything other than a 480 Wye give the 480/277 voltages 
indicated above?
-          If the 4th wire is a neutral (I certainly hope it is), where 
might I find the ground electrode conductor (the building is relatively 
new, less than 10 years I believe.).  FYI, the building is metal.

I look forward to your comments

Howard “Scot” Arey
254-300-1228
scot.arey at solarcentex.com

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