5 HP motor on off switch

[kevin nee]

Hello, I purchased a 20 inch RBI 20 inch planer that was 3 phase. I purchased a 5 HP Leeson motor
I installed an in-line 220 switch and it seems to work fine. 1 man shop with very little use. Do I need a magnetic starting switch?
Thanks in advance, Kevin

[David Kumm]

Is the switch rated for motor starting and are there internal overloads on the motor? Dave

[Terry Kelly]

I would say yes to the starter.....the switch more than likely isn’t rated for the amp draw of the 5hp motor which looks to be around 28 amps.....

[Dan Friedrichs]

A "starter" has two functions:

1) Switch motor on/off. If the switch you have is rated for the current the motor draws and is rated for motor loads, then it's fine. When a motor is switched off, energy stored in the magnetic fields can produce a big arc, which can damage the contacts of a switch not appropriately rated to handle it (the contacts need to be big and "snap" open quickly).

2) Overload protection. It monitors the motor current and keeps you from drawing an amount that would damage it. This function may be built into the motor (if so, it will have a "reset" button somewhere).


Neither of these is "required" - you could use a "regular" switch to turn a motor on/off, but you'll eventually wear it out. Likewise, overcurrent protection isn't required, but it's cheap insurance against damaging an expensive motor.

Finally, a magnetic starter is nice because it will turn off and stay off if power blinks. Don't want a tool to come back to life while you're standing in the dark wondering where your hands are.

[Doug Garson]

I think the question the OP is asking is whether he needs a magnetic starter not just a starter switch. If so I believe the purpose of a magnetic starter is to prevent the machine from restarting after a power interruption if the switch is left on and the power comes back on.

I see Dan beat me to the purpose of the magnetic starter.

[Bill Dufour]

commercial shop or school shop yes.
Bill D.

[John K Jordan]

Hello, I purchased a 20 inch RBI 20 inch planer that was 3 phase. I purchased a 5 HP Leeson motor
I installed an in-line 220 switch and it seems to work fine. 1 man shop with very little use. Do I need a magnetic starting switch?
Thanks in advance, Kevin

I use this switch with two 5 HP motors. It is rated as an industrial grade AC manual Motor Starter / motor ontroller or motor disconnect. This model will handle 30 amps. My use is for a 5hp air compressor and a 5hp cyclone dust collector with a Leeson motor.

Oops, forgot to include the latest link:
https://www.amazon.com/Leviton-MS302-DS-Disconnect-Industrial-Non-Grounding/dp/B002MPQ51O


JKJ

[Charles Lent]

A properly sized motor starter will last longer and will provide overload protection for the motor too. With push button control of the motor starter it will also give you the added safety of not starting up on it's own if you should experience a power failure during a cut, when the power comes back on.

Charley

[David Kumm]

There are two types of motor starters with overloads. A manual starter has maintained contacts and is basically a switch rated for motors. It will start the machine anytime the on button is in the contact position. A magnetic starter uses a coil and momentary buttons. When the power is cut, the machine stops and needs to be restarted. It is an additional safety device. Dave