The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!


2017 NEC and Related
2017 NEC
Now Available!

Recent Posts
Parking lot pole light swap....
by gfretwell
Yesterday at 08:46 PM
International Wire Colour Codes
by Tjia1981
10/23/16 12:08 PM
Son of Sparky
by HotLine1
10/20/16 07:43 PM
Speaking of Plugmold ...
by gfretwell
10/17/16 02:37 PM
Broken battery charger? Check for cobwebs!
by gfretwell
10/17/16 02:30 PM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 14
ghost307 7
HotLine1 7
renosteinke 6
Potseal 4
Who's Online
0 registered (), 265 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#189530 - 10/14/09 07:09 PM Transfer switch before metering?
ayrton Offline

Registered: 12/21/01
Posts: 205
Loc: Pa
We have a somewhat unique service set up at a bank/post office. 500kcmil fed from utility pole mount xfmrs to trough and two meters on exterior wall. 500's go through trough and feed a 400a 3p 4 wire meter, than into buiding to disconnecting means. 3/0 is tapped off of 500's in trough to feed a 200a 3P 4w meter than travels inside to disconnecting means.

I would like to pull 500's out of trough (line side of meters) repace trough with 24x20 nema3 box. splice onto the 500s and go to my new 400a disconnect, which will than feed transfer switch. Than from transfer switch, come back to nema 3 box and feed meters. Is this legal?

2014 / 2011 NEC & Related Books and Study Guides
#189531 - 10/14/09 08:37 PM Re: Transfer switch before metering? [Re: ayrton]
Yoopersup Offline

Registered: 03/04/03
Posts: 826
Loc: Michigan
Why not get a Service rated transfer switch , go from Tap to meter, Meter to Transfer switch, Transfer switch to service rated Disconnect Switch.
I think the Power Company won't be to happy about having a Transfer switch ahead of the metering.
You also can't mix Service conductors & Conductors after the Service disconnect(feeder) together.(230.7)2005 NEC in the same conduit or J box.

#189961 - 10/30/09 08:13 PM Re: Transfer switch before metering? [Re: ayrton]
Niko Offline

Registered: 08/17/06
Posts: 358
Loc: Campbell, CA
It does not sound like it is a good design.
Every time the genset kicks on and provides power it will go through the meter and the customers gets charged for it?

It may be best to consult with the local POCO.
Be kind to your neighbor, he knows where you live

#190000 - 11/02/09 10:46 AM Re: Transfer switch before metering? [Re: Niko]
SteveFehr Offline

Registered: 03/19/05
Posts: 1192
Loc: Chesapeake, VA
The service-rated transfer switch should only ever go downstream from the meter, not upstream of it.

If you want both services to be on generator, you would need to get two transfer switches. One generator can feed multiple transfer switches, you just have to be careful about what you do with the neutrals when you're dealing with multiple services like that.

#190003 - 11/02/09 11:39 AM Re: Transfer switch before metering? [Re: SteveFehr]
Yoopersup Offline

Registered: 03/04/03
Posts: 826
Loc: Michigan
You can also buy CT metering units. That meter it after utility meterting if you want to know power usuage, There used all the time in office building with several tendent but only one utility co. Main meter.


ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals