DaveBowden
Senior Member
- Location
- St Petersburg FL
A wholesale fish operation is moving to a new location and needs to have the service upgraded from the existing 100Amp single phase to a 400Amp 3 phase.
The load calculations come up to about 360 Amps with everything figured at 100% (no derating).
The customer naturally wants to keep costs to a minimum since he is just leasing the property,
The engineer he hired to draw the electric for permitting (riser diagram, load calcs, and panelschedule) wants to parallel two 4 inch conduits with 4 250MCM Cu in each conduit. When I asked him why he wanted to oversize the wire so much he said its because he doesn't know what they may "plug in" in the future.
I think paralleled 3/0 THHN CU in 3" conduit, since it would be protected with a 400 Amp main breaker, is adequate and is all that needs to be installed.
How do you convince a customer that the civil engineer (not electrical engineer) that they paid to draw this print is costing them unnecessary money? How do you convince the engineer that you don't need to ignore all the testing laboratories findings as far as protecting wires are concerned by oversizing everything by more than 25% ?
I tried to explain to him that there is no danger in running 400 Amp wire for a service that is rated for 400 Amps and protected at 400 Amps, but got the "That's how I do it" response.
The load calculations come up to about 360 Amps with everything figured at 100% (no derating).
The customer naturally wants to keep costs to a minimum since he is just leasing the property,
The engineer he hired to draw the electric for permitting (riser diagram, load calcs, and panelschedule) wants to parallel two 4 inch conduits with 4 250MCM Cu in each conduit. When I asked him why he wanted to oversize the wire so much he said its because he doesn't know what they may "plug in" in the future.
I think paralleled 3/0 THHN CU in 3" conduit, since it would be protected with a 400 Amp main breaker, is adequate and is all that needs to be installed.
How do you convince a customer that the civil engineer (not electrical engineer) that they paid to draw this print is costing them unnecessary money? How do you convince the engineer that you don't need to ignore all the testing laboratories findings as far as protecting wires are concerned by oversizing everything by more than 25% ?
I tried to explain to him that there is no danger in running 400 Amp wire for a service that is rated for 400 Amps and protected at 400 Amps, but got the "That's how I do it" response.