I often get asked on what components to use in VFD cabinets how to wire 240VAC voltage. The attached files give some general recommendations, one should always follow local electrical code requirements and the VFD manuals recommendations as to wiring and fusing. The attached information is based on non-industrial settings, i.e. home shop installations. Since I am not an electrician, use this information at your own risk and check with your local electrician if you need specifics on your local code. Since this information has been asked on several PM lathes/mills I am parking it in the Precision Mathews section. In the basic wiring schematic I usually recommend a main power disconnect at the VFD enclosure and some form of overload protection if you are not using a dedicated circuit with an appropriate sized breaker at the electrical panel. The disconnect switches are usually 3 poles, you would use 2 poles for single phase. Enclosures, I usually recommend a minimum of 14" tall, 12" wide and 8" deep for VFDs up to 3 Hp, up to 5 Hp you may want a 16" by 14" cabinet. The VFDs are very tall, and with a backing plate you loose height. A 6" deep cabinet will not fit most VFDs unless you cut the front panel and extended it through. You may be able to pick up a cabinet on eBay at under $100, but you need to do a lot of looking and you might get lucky. Otherwise for a little more I recommend getting one from Automation Direct, usually a fiberglass reinforced plastic type. I recommend snap clasps, a clear window is nice but not necessary. Once the VFD is running, you do not need to look at it unless there is a fault. Overload protection: fuses work quicker than breakers, and have a much lower fault current, they are usually used to protect the device. Breakers usually are used to protect the wiring. Even with a electrical panel breaker, machines/equipment are usually fused locally. The usual arrangement with VFDs 3Hp and under is to use the larger J class type fuses, I prefer the finger safe fuse holders as opposed to the open type. Note that fuse holders are both specific to the class of fuse and they have specific ranges, so on J class you will see holders up to 30A, then over 30A to 60A, etc. With VFDs you must use high speed fuses, not standard or dual element delayed type. These fuses are not inexpensive, but if you do not use the correct type size fuse it does you little good. Fusses are not interchangeable between class types, because they have different thermal characteristics and overload properties. If space is limited, then one can use CC class fuse holder and high speed fuses, CC class fuse are NOT midget fuses. Some manufactures recommend a larger size fuse when going from something like a J class to a CC class, so check your manuals or call technical support. Supplemental breakers/fuses. You may want to add supplemental breakers to protect other components and wiring in the system. I often recommend a 3A supplemental breaker to protect the power going to the lathe cabinet, and to power a coolant pump contactor/relay if used. A breaker will not protect a coolant pump from overload, only a direct short. If you want to protect the coolant pump from thermal overload (such as if the impeller gets locked), then you must use an appropriate sized thermal overload relay on the coolant contactor. I often add a single gang 120VAC socket at the machine or a dual gang sockets. I use a 15A supplemental breaker to protect the wiring going to the socket(s), this also requires that a neutral wire is pulled to your VFD cabinet and then on to the 120VAC socket. On cooling the VFD cabinet, with two vents, you can often get away with no auxiliary cabinet fan, but in this case I recommend that the VFD fan is set to run whenever the VFD is running the motor, there is usually a setting where it will run X minutes after the motor is stopped. If you add an auxiliary cabinet fan, I usually recommend mounting it on the bottom inlet with a filter so the fan blows into the cabinet (positive pressure). The fan is under the VFD, blows air over it and either out the top or side of the cabinet. With an auxiliary fan it turns on with the VFD cabinet power and runs continuously, the VFD fan is set to come on only if the heat sink goes beyond a fixed temperature. The advantage to an auxiliary fan is that the VFD fan will probably not turn on, the VFD fan (and components) will last longer, and an auxiliary fan is much cheaper to replace. Braking resistor is sized to your VFD. I have never seen one get past luke warm. They do have very high voltage on the wiring when braking is engaged, something like 380VDC. They can be mounted on the side of the cabinet or on the back panel. If others have comments or recommendations, please add to this post.