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#217470 - 08/12/16 12:53 AM Service Entry Switchgear/Switchboard design......
devereaux Offline
New Member

Registered: 07/30/16
Posts: 4
Loc: CA
What is the most appropriate switchgear/switchboard choice for a single utility CT metered 1200 Amp 480/277 Volt 3 phase outdoor located service entry install????

Source power will be bottom fed from a trenched set of four parallel 300A feeders in plastic conduits from the secondary of a 1000 kVA pad trafo located 8 ft away. There will be 6 200A disconnect breakers supplying 6 top fed outgoing conduits attached to external wall feeding 6 200A 3 phase panels on the inside of same wall.

A single CT utility meter is part of this package as are the 6 200A disco breakers. No 1200 A main disconnect is specified.

What is most cost effective smallest footprint way to go here. Any manf, Eaton, Square D, other considered. Alternate design approach welcomed.

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#217471 - 08/12/16 06:40 AM Re: Service Entry Switchgear/Switchboard design...... [Re: devereaux]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6785
Loc: Brick, NJ USA
A common install on my side of the country is as follows:
4x4" PVC, with 4x600KCMil Cu., from pad mount to gear, bottom entry.
CT Section and distribution in adjacent sections.
(NO Main OCP)

Sq D 3R equipment is nice; other brands are choices based on $$$, availability, and personal preferences.

However, a check with your local AHJ, and local POCO should be your first step, as local rules may apply.

On a personal note, the possibility/probability of the 'future' of the site should also be considered. I have seen quite a few of 'MLO' installs having to be replaced with 'MOCP' due to space/tenant changes.

Feeder breaker buss should allow the replacement of a 200 amp original CB with a larger frame IF needed down the road.

Comments are just thoughts from my experiences.
_________________________
John

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#217474 - 08/12/16 11:31 AM Re: Service Entry Switchgear/Switchboard design...... [Re: devereaux]
renosteinke Offline
Cat Servant
Member

Registered: 01/22/05
Posts: 5299
Loc: Blue Collar Country
You really, really, really need to have a chat with the power company. That's the first step to avoiding expensive issues later.

Then, you need to have a long chat with your customer. Examine not just his use for the property, but whether his real 'business' is selling it off in a year or two.

Let me describe four similar installations I have seen:

Location "A" served a 'strip mall.' The original design 'cheated' by having one of the units also power the common spaces - a ploy to exploit the 'six disconnect rule.' Naturally, this became an issue later, when the new owner sought to change things.

Location "B" was served by an underground feed from a pole-mounted transformer platform. The CT enclosure was part of the main switchgear cabinet.

Location "C" was served by a ground-mounted transformer. In this case, the CT cabinet was at the transformer, and the switchgear at the building was little more than a disconnect switch and a breaker.

Finally, location "D" was designed as a simple light industrial unit, with provision to divide the space later. Well, that happened ... then another unit was added ... then another ... before you knew it, meter #6 was going up. All cobbled on to the original service.

Had the owner of "D" been honest about his plans, and spent a few more dollars, equipment would have been installed that allowed for ready expansion. Plus, the issue of six disconnects would have been avoided. Instead, the guy paid more- for a final mish-mash of equipment. Pay now, or pay later.

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#217476 - 08/12/16 01:00 PM Re: Service Entry Switchgear/Switchboard design...... [Re: HotLine1]
devereaux Offline
New Member

Registered: 07/30/16
Posts: 4
Loc: CA
Originally Posted By: HotLine1
A common install on my side of the country is as follows:
4x4" PVC, with 4x600KCMil Cu., from pad mount to gear, bottom entry.
CT Section and distribution in adjacent sections.
(NO Main OCP)

Sq D 3R equipment is nice; other brands are choices based on $$$, availability, and personal preferences.

However, a check with your local AHJ, and local POCO should be your first step, as local rules may apply.

On a personal note, the possibility/probability of the 'future' of the site should also be considered. I have seen quite a few of 'MLO' installs having to be replaced with 'MOCP' due to space/tenant changes.

Feeder breaker buss should allow the replacement of a 200 amp original CB with a larger frame IF needed down the road.

Comments are just thoughts from my experiences.



Thank you for this info. Is it OK to install some of the outgoing feeders later while the panel is hot and in service??? Only 4 may of the 6 will be wired up initially. The remaining two will be left for expansion.

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#217477 - 08/12/16 01:20 PM Re: Service Entry Switchgear/Switchboard design...... [Re: renosteinke]
devereaux Offline
New Member

Registered: 07/30/16
Posts: 4
Loc: CA
Originally Posted By: renosteinke
You really, really, really need to have a chat with the power company. That's the first step to avoiding expensive issues later.

Then, you need to have a long chat with your customer. Examine not just his use for the property, but whether his real 'business' is selling it off in a year or two.

Let me describe four similar installations I have seen:

Location "A" served a 'strip mall.' The original design 'cheated' by having one of the units also power the common spaces - a ploy to exploit the 'six disconnect rule.' Naturally, this became an issue later, when the new owner sought to change things.

Location "B" was served by an underground feed from a pole-mounted transformer platform. The CT enclosure was part of the main switchgear cabinet.

Location "C" was served by a ground-mounted transformer. In this case, the CT cabinet was at the transformer, and the switchgear at the building was little more than a disconnect switch and a breaker.

Finally, location "D" was designed as a simple light industrial unit, with provision to divide the space later. Well, that happened ... then another unit was added ... then another ... before you knew it, meter #6 was going up. All cobbled on to the original service.

Had the owner of "D" been honest about his plans, and spent a few more dollars, equipment would have been installed that allowed for ready expansion. Plus, the issue of six disconnects would have been avoided. Instead, the guy paid more- for a final mish-mash of equipment. Pay now, or pay later.


The requirement for a single utility meter serving the 6 200A feeders is rock solid here. Are you suggesting a CT Panel with a 1200 main Disconnect Safety Switch outside would be more cost effective since that approach would work here also????

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#217479 - 08/13/16 02:05 AM Re: Service Entry Switchgear/Switchboard design...... [Re: devereaux]
renosteinke Offline
Cat Servant
Member

Registered: 01/22/05
Posts: 5299
Loc: Blue Collar Country
The answers to your questions are NO and NO.

Adding the outgoing feeders while the panel is hot would clearly violate OSHA's interpretation of 70E. It's unsafe.

I make no representation as to what approach is most economical / cheapest. My post should have made clear that there is no substitute for good design. It also should have been clear that -since the CT is power company equipment- it is THEIR choice how things will be done.

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#217481 - 08/13/16 03:37 PM Re: Service Entry Switchgear/Switchboard design...... [Re: devereaux]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6785
Loc: Brick, NJ USA
OK, time to backup a little here.

Installing 'some' of the tenant feeders from the load side of their respective main CB should not be an issue. You would be making connections on the load side of the CB within the gear. Think similar to installing a branch circuit into an existing panel.

Yes, caution must be paramount when working within an energized panel, even though you are connecting to the load side of a feeder CB.

My opinion, and I believe Reno is going the same direction is that the design MAY think about a 'MAIN' for the possibility of future needs or expansion.
_________________________
John

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#217484 - 08/13/16 06:01 PM Re: Service Entry Switchgear/Switchboard design...... [Re: HotLine1]
devereaux Offline
New Member

Registered: 07/30/16
Posts: 4
Loc: CA
Originally Posted By: HotLine1
OK, time to backup a little here.

Installing 'some' of the tenant feeders from the load side of their respective main CB should not be an issue. You would be making connections on the load side of the CB within the gear. Think similar to installing a branch circuit into an existing panel.

Yes, caution must be paramount when working within an energized panel, even though you are connecting to the load side of a feeder CB.

My opinion, and I believe Reno is going the same direction is that the design MAY think about a 'MAIN' for the possibility of future needs or expansion.


It is my belief that you may be correct re connecting to load side since I expect that an expensive and large Switchboard should have the real estate and provision for a trained pro doing so with caution of course. I would have all 6 breakers powered down for even more caution.

As you suggest I would like to install a main ahead of the 6 pack but it is a cost driver and is not mandated by NEC rules so customer will question. Again he (like so many) thinks the future will see no change to his current plan.

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#217485 - 08/13/16 06:19 PM Re: Service Entry Switchgear/Switchboard design...... [Re: devereaux]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6785
Loc: Brick, NJ USA
Just an FYI....The buss will still be 'hot'.

Also, you should be able to see the dimensions available on the cut-sheets from the mfg. if you request them
_________________________
John

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