Temporary power for 6 live suites

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DansProfElec

Member
Location
Huntington beach, CA
I have a commercial project upgrading the existing 1200 Amp 120/208 switchgear with new equipment, but need to keep the 6 existing tenants up and running while we remove the existing equipment and install the new switchgear. The problem comes with providing a temporary power solution that doesn't cost as much as the whole upgrade. All the upgrades we have done to date were on projects were no tenants were present, so temp power was simple.

SDG&E (San Diego Gas & Electric) will give us (max) 400 amps out of their transformer. All the subpanels in the 6 suites are flush mounted, bottom fed through conduit under the fondation. Half of the panels are burried in rooms that are hard to get to. Subpanels are rated (1 - 200 Amp, 2 150 Amp, 3 - 100 Amp subpanels). The total building measured load for any one phase is under 250 Amps.

I had the city head Electrical inspector and the SDG&E Sr. Planner on site and they were scraching their heads on how to go about it. The SDG&E Planner wanted us to install a 400 Amp main disconnect with meter socket and with 6 main breakers (at a cost of about $8,000.00) I'm trying to get him to agree to use 2 200 amp meter panels and find a over the roof connection method (the trans fomer is within 60 feet of the building.

If anyone has some experienc with the same kind of problem of hooking up the 6 subpanels (by top feed) in the suites to temporary power I would love to hear.

Dan
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Dan considering we are not there it is tough to come up with ideas. :)

My first thought is why can't this be scheduled as a shut down and then just change the service as quick as you can?

How long are we talking? 12 hours, 18 hours, 24 hours?

Other then that it seems you would have to run a temp cable into each tenants panel, lift the feeders and land the temps. A generator rental might be cheaper then the temp service they are suggesting.
 
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DansProfElec

Member
Location
Huntington beach, CA
Temp power for 6 live suites

Temp power for 6 live suites

Unfortunately the location of the existing transformer and the switchgear make it difficult to do things quickly. THe main feeders from the Utility Transformer are bottom fed to a surface mount 50 year old pull box with buss bars to Test block meter panels (no main cut-off). We have to remove the existing hardware, shorten the 4" main feeder conduits, pour a concrete slab and then we can put the new switchgear in. The gas utilities are right next to our main service conduit so there is no place to put the switchgear but right on top of where the existing hardwae is. It would have been easier to have a new location for the switchgear and change all the bottom feeds to top feed and make the connectiona after the new switchgear service was energized.
 
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wireguru

Senior Member
was the $8,000 because you have to buy a piece of gear? There are places you can rent from. Rosens is one, they are off the 5 fwy in pico rivera not too far from you.

The feeds to the subpanels, are they underground or do the come out the top of the old gear? Is the old gear inside or outside?
 
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DansProfElec

Member
Location
Huntington beach, CA
Temporary power for 6 suites

Temporary power for 6 suites

Thank you all for your suggestions.

I am looking into the rental company "Rosens" for some gear. The SC cable, is it similar to SO cable? I have access to SO cable, but the suppliers only carry up to 6/4. 6/4 gives me 75 Amps which is ok for 4 of the suites, but 2 of the suites draw 75 amps on 2 of their phases. I need to have at least 2 80amp wire runs and 2 80 amp breakers for those two suites.

The building is all underground feed to all the sub panels. 2" PVC underground and Rigid from the panels to concrete floor. All the sub panels are flush mounted. One of the Suies is occupied by US Bank and they refuse to go on a generator. There are homes right behind this shopping center and they have noise rules so generators are out. Gas meters and pipe prevent us from building the new switchgear at a parallel location and leaving the existing switchgear live, so it all has to be removed first and power disconnected.

I'm looking for 2 used nema 3 outdoor Sunbpanels to put on the roof each fed with a 3/0 cables from the temp power poles. Each 200 Amp sub panel will have 3 breakers (one for each suite). I wanted to do a pull box with 3 suites per pull box, but the timing on connect disconnect is going to make too much downtimes and the teneants are already complaining about us being in there and shutting them down. The bank has to have it's shut down durring the day as their people have to be there to watch us.
 
W

wireguru

Senior Member
DansProfElec said:
Thank you all for your suggestions.

I am looking into the rental company "Rosens" for some gear. The SC cable, is it similar to SO cable? I have access to SO cable, but the suppliers only carry up to 6/4. 6/4 gives me 75 Amps which is ok for 4 of the suites, but 2 of the suites draw 75 amps on 2 of their phases. I need to have at least 2 80amp wire runs and 2 80 amp breakers for those two suites.

The building is all underground feed to all the sub panels. 2" PVC underground and Rigid from the panels to concrete floor. All the sub panels are flush mounted. One of the Suies is occupied by US Bank and they refuse to go on a generator. There are homes right behind this shopping center and they have noise rules so generators are out. Gas meters and pipe prevent us from building the new switchgear at a parallel location and leaving the existing switchgear live, so it all has to be removed first and power disconnected.

I'm looking for 2 used nema 3 outdoor Sunbpanels to put on the roof each fed with a 3/0 cables from the temp power poles. Each 200 Amp sub panel will have 3 breakers (one for each suite). I wanted to do a pull box with 3 suites per pull box, but the timing on connect disconnect is going to make too much downtimes and the teneants are already complaining about us being in there and shutting them down. The bank has to have it's shut down durring the day as their people have to be there to watch us.
Click to expand...

type SC is a portable single conductor cable. Its basically the legalized version of welding cable.
 
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