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GIS Switchgear cable vault

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rockman7892

Electrical
Apr 7, 2008
1,156
I'm discussing a proposed project where customer wishes to place new 69kV GIS switchgear in a pre-fabricated building. Most buildings I've seen with GIS switchgear had a cable vault in basement of building for routing of cables below switchgear and then terminating through floor to switchgear.

Has anyone seen what is typical or standard with GIS in pre-fabricated elevated buildings? I've seen conceptually where some have GIS on elevated 2nd floor with first floor (ground level) being dedicated to cable management. If routed below building in this case should ground floor be enclosed or can it remain open with cable tray below the building?

Incoming/outgoing cable will be both UG ductbank as well as OH cable tray.

I'm also curious to hear from others who have done GIS in pre-fabricated buildings if its typically better to install GIS gear at the building manufacturer to ship with building or install once building has arrived on-site?
 
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In doing some research I don't see many GIS building that are pre-fabricated (pre engineered elevated buildings. Most of these appear to brick and mortar buildings or buildings with pre-fabricated concrete walls. Most of these buildings appear to have basement cable vault or enclosed first floor cable vault for cable tray and cable management.

In seeing this I'm wondering if an elevated pre-fabricated building is even a feasible approach? My experience is mostly limited to MetalClad MV gear in such buildings where cable is routed in cable tray in open area underneath building

Would be interested to hear from others (good or bad) any experience with prefabricated elevated GIS buildings.
 
I'm going to walk down a 138kV GIS project this afternoon. The OEM will also be there and I'll see if they have any experience with prefab. The 5 other GIS projects I've been involved in have been the brick and mortar type.
 
I asked the ABB GIS guy on site about your query. He had never seen a prefab building. My guess is that GIS is (at least in USA) typically used where space is a premium. In my case today, that was in the downtown area. All HV and MV cables came in from manholes into the basement. As you can imagine, there are all kinds of underground utilities in a downtown area.

My other thought was local building codes. Will the city allow a prefab building?
 
See if the illustration below can help.

GIS_SECTION_gyc17m.jpg
 
thermionic1 - I appreciate you GIS guy on-site at recent job walk. The particular project that I'm looking at is for an industrial site so city approval would not apply here. The few GIS buildings that I've seen on industrial sites have all been brick & mortar as well.

cuky2000 - Thanks for sharing drawing. That appears to be brick & mortar building with cable vault basement. Customer has a similar type of existing building on site however instead of basement the cable vault is actually located on first floor with GIS on 2nd.

Everything that I'm seeing seems to lean towards a brick and mortar build due to cost and less complexity with multiple shipping splits, etc.. for prefab building. From what I understand GIS should not be installed at building manufacturer and shipped to site similar to AIS due to risk of damage with seals, gaskets, etc.. during transport. Having to install GIS at site would somewhat defeat purpose of offsite prefab built and benefit of installation and commissioning prior to arrival at site.

I'm curious if it is standard to have HV (69kV etc..)cable vaults (cable management) enclosed such as with brick and mortar or if it can be left open with tray similar to what I've seen with LV cables under pre-fab buildings?
 
Rockman - I'll be back on site today and take a few pics. We have Oil filled and XLPE lines on this project.
 
I do not see a problem designing a cable vault on the first floor with GIS on 2nd. (See Ex. picture below). The superstructure usually is a steel frame supported in a concrete foundation with anchor bolts. The GIS building deck may be covered with insulated siding panels. No necessary the building has to be brick and mortar. The building shall be in compliance with the State Building Code.

In all the GIS that I see, the components are shipped loos and assembled on-site using the overhead crane included in the design. installation and commissioning prior to arrival at the site is not the standard practice.

Two_Story_Pre-Eng_Bldg_m0andg.jpg
 
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