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#86576 - 11/12/03 02:01 PM 3 Phase Branch Circuits
RDominey Offline
Junior Member
Registered: 11/12/03
Posts: 1
Loc: Jacksonville, Fl, USA
My company builds rides for amusement parks. The ride vehicles and control system is built in Italy. The system is powered by 3phase 208V distributed to the ride vehicles through the control panel along 390 ft of insulated bus rails and picked up by contactors that deliver power to a variable speed motor controller to a 2hp delta ac motor.

My Question deals with distribution, branch circuits and circuit protection.

The 3Phase comes into the panel at 100A, goes through a panel door disconnect, a 125A 3Phase GFI unit, a 3 pole contactor and then is distributed to 4 connection points in the 390ft track using 8AWG stranded THHN cable. The four connection points are at equal distances apart. The power is picked up from the bus rails at each vehicle with contactor brushes and sent trough a 12A circuit breaker to the AB PowerFlex-4, 8A motor controller.

Would not the NEC requirement to protect branch circuits apply to each of the four distribution branches ran to the bus rail?

How would you calculate the protection necessary at each branch with 10 vehicles on the bus rail at any given time and not always evenly distributed?

Would 8AWG cable be enough for the branch circuits?

Any help here would be greatly appreciated. I can send a drawing and photos if necessary.
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#86577 - 11/12/03 02:13 PM Re: 3 Phase Branch Circuits
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
First off any chance this is a Zamprella made ride?

Second, the NEC is not concerned with the factory wiring of equipment.

The Feeder to this ride must be NEC compliant, but beyond that it is up to the factory to provide the correct wiring and get the unit approved by testing labs.
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Bob Badger
Construction & Maintenance Electrician
Massachusetts
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