If you're hooking multiple Leslies (or other ToneCabinets to your organ, you probably don't want all of the AC power for those cabinets going through your run switch.
The best solution to this problem is to install a relay to handle the switching of power to the ToneCabinets.
Here's one I've used (ordered from AlliedElectronics):
Mfr.'s Part #: 258-62T200 Allied Stock #: 789-0109 Manufacturer: C.I.I. MIDTEX Description: Miniature PCB Relay, DPDT 15A, 120VAC, 3400 Ohms, QC/Solder Lug Term, Flanged Cover Cost: ~US$5.50
Distinguishing features:
I'm sure many other relays would work fine too.
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