[RE-wrenches]

[Darryl Thayer]

HI 
Check your voltages again.  It sounds like you have an
open delta, centertap ground on one phase, and a high
leg. (look on the pole and see if you have 2
transformers)  (the voltages I expect are 120, 120,
240 on the heavy phase and about 190 on the high leg)
 The reason for this type of service was to provide
large 240 volt and 120 volt loads and a small three
phase loads.  Indeed it sounds as if the three phase
has an oversized fuse on the high leg..

some utilities will not allow you to connect inside
the CT can.  Depending yupon how you et your line tie,
such as from multi inverters, you can selectivly feed
the heavy phase, and put a lighter (less inverters) on
the high leg.  If you are going to use a single
inverter you have a lot more work and problems in the
service.  

--- Mark Frye <markf at berkeleysolar.com> wrote:

> 
> I am working with small commercial group that runs
> various manufacturing 
> equipment in a small building.
> 
> The aging service is a 3 phase, 240V delta, with a
> 208V leg opposite the 
> neutral (I am not sure if it is called a "stinger
> leg" if it isn't 
> 277V.) The service entrance conductors include 1 -
> 500 MCM grounded, 2 - 
> 500 ungrounded, and 1 - 1/0 ungrounded (for the
> "stinger leg".) I have 
> not yet determined what type wire they are.
> 
> My understanding is that the stinger leg wire in the
> service drop is 
> also "undersized".
> 
> The service entrance conductors pass through a CT
> can and terminate in a 
> 3 phase, 240V, 400A fused disconnect. The fuses are
> 2 - 400A, and a 300A 
> on the stinger leg (the 300A fuse is much newer than
> the other two.) I 
> have not yet tested or determined what loads are
> connected to the 
> stinger leg, what the demands actually are or why it
> was recently 
> replaced.
> 
> The utility has inspected this equipment and said
> they were not 
> interested in upgrading the service drop or
> requiring an improvement of 
> the service equipment.
> 
> One question I have is who “owns” the service
> entrance conductors?  My 
> understanding is that the they “belong” to the
> premise and in this case 
> the stinger leg with the 300A fuse should be
> upgraded by the owner, 
> regardless of what the utility does with the drop.
> Or else, they should 
> replace the 300A fuse with a 150A.
> 
> However, since there is no capacity in the fused
> disconnect to back feed 
> a 30kW PV system, I will be connecting on the line
> side, in the CT can. 
> In this case the existing 1/0 is capable of handling
> the back feed 
> current.
> 
> I guess I need to really find out what kind of
> current is running in the 
> stinger leg.
> 
> If the 300A fuse is needed to serve the loads, I am
> thinking I will 
> upgrade the service entrance stinger leg conductor
> and do a line side 
> tap in the CT can.
> 
> Any advise on how to proceed would be welcome.
> 
> Mark Frye
> Berkeley Solar Electric Systems
> 
> 
> - - - -
> To send a message: RE-wrenches at topica.com
> 
> Archive of previous messages:
> http://lists.topica.com/lists/RE-wrenches/read
> 
> List rules & how to change your email address:
> www.mrsharkey.com/wrenches/etiquette.php
> 
> Check out participant bios:
> www.mrsharkey.com/wrenches/
> 
> Hosted by Home Power magazine
> 
> Moderator: michael.welch at homepower.com
>
> 
> 


__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com 


- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://lists.topica.com/lists/RE-wrenches/read

List rules & how to change your email address: www.mrsharkey.com/wrenches/etiquette.php

Check out participant bios: www.mrsharkey.com/wrenches/

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com
--^----------------------------------------------------------------
This email was sent to: michael.welch at homepower.com

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?p=TEXFOOTER
--^----------------------------------------------------------------