Confusing Panels

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curt swartz

Electrical Contractor - San Jose, CA
Location
San Jose, CA
Occupation
Electrical Contractor
Yesterday I was sent the engineered drawings for a project that the owner and general contractor wants priced ASAP. There are may details missing but the panels really have me confused.

What size is the breaker in the meter main? Is this project 3 phase or single phase? Many of the breaker numbers don't match the phase (A,B,C) they should be. Some breakers next to each other are supposed to be on the same phase.

I'm not sure where the meter main is supposed to get located but Panel A and Panel B are in separate buildings so they should have main breakers and their own GES.

Most of the lighting is shown TBD and there isn't any CA T24 lighting calc's or controls shown.

I don't get how an engineer can release drawing like this.
Meter Main.jpg
Panel A.jpg
Panel B.jpg
 
You have a bum set of drawings, that's for sure. I would not want to bid that. But I would suggest pricing it as if it were a three-phase system, with a 400 amp main breaker, a 400 amp panel A, and a 200 amp panel B. I don't have time to check the wire sizes, but I know that the feeder from A to B needs another wire.
 
charlie b said:
... but I know that the feeder from A to B needs another wire.
Click to expand...
Nah. It even says so right in the table header: 120/240V, 1 phase, 3 wire... and you get that by dropping one wire (the neutral) from Panel A, which is 120/240V, 1 phase, 4 wire.

:lol::lol::lol:
 
I only see one typo.
Panel A is shown as 1phase 4 wire, but based on its feed, it is likely a (240/120V) 3-phase 4-wire wild leg. Panel B is a 1-phase 3-wire 120/240V.

Only you can decide if you want to bid it this way or to ask for an RFI.
 
jim dungar said:
I only see one typo.
Panel A is shown as 1phase 4 wire, but based on its feed, it is likely a (240/120V) 3-phase 4-wire wild leg. Panel B is a 1-phase 3-wire 120/240V.

Only you can decide if you want to bid it this way or to ask for an RFI.
Click to expand...
If panel A is supposed to be 3-phase wild leg delta then there are several single phase breakers on the wild leg.

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curt swartz said:
Yesterday I was sent the engineered drawings for a project that the owner and general contractor wants priced ASAP. There are may details missing but the panels really have me confused.

What size is the breaker in the meter main? Is this project 3 phase or single phase? Many of the breaker numbers don't match the phase (A,B,C) they should be. Some breakers next to each other are supposed to be on the same phase.

I'm not sure where the meter main is supposed to get located but Panel A and Panel B are in separate buildings so they should have main breakers and their own GES.

Most of the lighting is shown TBD and there isn't any CA T24 lighting calc's or controls shown.

I don't get how an engineer can release drawing like this.
Click to expand...

I m thinking the garage is attached, since the branch circuits for the garage originate in panel A.

Since this is a mixed occupancy building church/dwelling if it was a 3ph system you would expect to see a 120/208 volt system. I do not see dwellings supplied by a delta 120/240 3ph system

Since the line diagram has new designations on this equipment I automatically ask myself where is the existing.

I would look at these drawings to be preliminary and would suspect these drawings will end up with a lot of changes after they are submitted to a building department for plan review.

Issues like is a second or additional service even going to be approved for this building. I would suspect the issue of arc fault protection to come up, they may even get kicked back to the design professional for a complete redo.
 
david said:
I m thinking the garage is attached, since the branch circuits for the garage originate in panel A.

Since this is a mixed occupancy building church/dwelling if it was a 3ph system you would expect to see a 120/208 volt system. I do not see dwellings supplied by a delta 120/240 3ph system

Since the line diagram has new designations on this equipment I automatically ask myself where is the existing.

I would look at these drawings to be preliminary and would suspect these drawings will end up with a lot of changes after they are submitted to a building department for plan review.

Issues like is a second or additional service even going to be approved for this building. I would suspect the issue of arc fault protection to come up, they may even get kicked back to the design professional for a complete redo.
Click to expand...

This may even be a mixed occupancy church /dwelling/ daycare

Other issues of emergency lighting, tamper receptacle extended in the daycare area.

Walk away or be very careful that you qualify your bid proposal with a very thoughtful statement protecting yourself.
 
Smart $ said:
While it may state 120/240V 1 phase 3 wire in header, the schedule shows loads on phase A, B, and C...???
Click to expand...

Where do you see specific bus connections for each load?
I have ordered many 3P 4W panels with custom bussing that effectively had a single phase portion with only A and C connections.
I would normally not try to rationalize any of the load calcs as part of my bid process.

Of course the typo could have been for a 208Y/120V 3-phase Panel A and a 120/208V 1-phase Panel B.

In either case an RFI is eventually needed before construction, but I see no reason to have a wholesale slam of the drawings.
 
When we get plans like that, it's usually right around the end of the year, before a code change, since the effective date is the submittal date.

With no T-24 you can't even start to bid this set as lights can't be listed as TBD.

If a plan checker couldn't check it, how are you supposed to bid it. I always thought that it was very daring to send out non approved plans for bids. I really like when they pick up their plans and call for rough the next day and I really really like the look on the contractors face when you start throwing stuff at him that he didn't bid.
 
jim dungar said:
Where do you see specific bus connections for each load?
I have ordered many 3P 4W panels with custom bussing that effectively had a single phase portion with only A and C connections....
Click to expand...
Schedule shows three ungrounded buses labeled ØA, ØB, ØC with loads connected under each... and no indication of custom busing.
 
There are no 3ph loads anywhere, except for the 3ph sub-feed to panel B....which has no 3ph loads.
That being said... since the main feed to panel A is 120/208 (more than likely)....the panel schedules are 3ph....then I would make the assumption it's 120/208.
The only error would be the sub-feed to panel B, which needs another hot

I would definitely try to get a clarification, but if they are dead-set on a price asap........It's all 3ph
 
Smart $ said:
Schedule shows three ungrounded buses labeled ØA, ØB, ØC with loads connected under each... and no indication of custom busing.
Click to expand...
During my years with a manufacturer and as a distributor, I was probably presented with contractor 'design and build' bid drawings like this, roughly 3 or 4 times per month. Someone just cuts and pastes a panel schedule, but they put some thought into the riser diagram.
 
jim dungar said:
During my years with a manufacturer and as a distributor, I was probably presented with contractor 'design and build' bid drawings like this, roughly 3 or 4 times per month. Someone just cuts and pastes a panel schedule, but they put some thought into the riser diagram.
Click to expand...
I think they forgot to put the "thought" process into the riser diagram, also in this case. :lol:
 
The GC was supposed to submit his bid including all trades this morning. I told him there is no way to give an accurate price with all the wrong and missing info on the current plans.

The power is pretty easy so if the engineer is not going to do a better job at the designer I would just do it myself. The lighting and control pricing could be anywhere on the map as far as price. I gave the GC a rough guesstimate and told him once the developer provides better plans we can provide a more accurate price.

I realize that the plans are a work in progress but I don't feel that the engineer should have ever let them leave their office in the current state. Ignoring the messed up panel schedules they have a single set of 4/0's for a 400 amp feeder. The calculated load for panel A is 284 amps so even if the meter main was 300 amps the feeder conductors are still too small. The feeder breaker for panel B is show to be 100 amps but the calculated load is 106 amps.

There are actually 3 separate buildings as part of this project. There is an existing building that the side where the service is currently located is being demolished. The plan discussed was to install a new service for the existing building at a new location and feed the other 2 new building from that service. Somehow the engineer is on a different path or was given bad info from the developer. Each building will need a service disconnect and GES.
 
Exactly -- a 3 phase 400a Meter/main combo -- feeder wire to panel A is 3 phase using the conduit a an EG but is undersized for load & OCPD, Feeder to panel be has a 3 phase 100A OCPD protecting a wire rated @ 115 amp but the max load on phase A is 106. Musta been a hot day on the ole porch as the cold ones were flowing :slaphead:
 
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