Home>Discussions>ELECTRICAL & LIGHTING>Installing A Thermal Overload
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A. Spruce
Installing A Thermal Overload

Quick question.

The motor on my Delta bandsaw burned out. I had it repaired and am in the process of reinstalling it in the machine. The repair shop gave me a thermal overload to install as well, but it did not come with instructions and I can't remember where they said to put it.

Where should the thermal overload be installed, before or after the on/off switch?

dj1
Re: Installing A Thermal Overload

Isn't it a safety issue, like a fuse? then it should go between the power and the motor. Do I make sense to you?

dj1
Re: Installing A Thermal Overload

Or, give the repair shop a call.

A. Spruce
Re: Installing A Thermal Overload

Looking ****** for a wiring diagram I've not found one for a 120v O/L protector. The one I was give only has two contacts.

You're saying that the O/L should be placed before the motor on the incoming power cord, correct?

It's Saturday, the shop is closed.

dj1
Re: Installing A Thermal Overload

logically, yes: between the power supply and the motor.

A. Spruce
Re: Installing A Thermal Overload

Ok, if it's wrong, it's YOUR fault! :p

dj1
Re: Installing A Thermal Overload

Worst case scenario: you'll have to call the fire dept. They're open on Saturday.

A. Spruce
Re: Installing A Thermal Overload

A friend just pointed out some silliness, which got me to thinking and to revise the question. I was thinking about the junction box mounted to the side of the motor and all connections being made there, which isn't how things work. What I needed to do was be thinking of the flow of power, which is "line-switch-load", which consequently made me revise the question to:

Where should the thermal overload be installed, before or after the on/off switch?

Which now that I've had all this time to think and type about it makes the question pretty darned silly! :rolleyes::D Now all I have to do is find my wire clamps so that the power cord can't be yanked and damage the O/L.

And DJ, if the fire department comes a calling, I'll be sure to send them your way. :p

motoguy128
Re: Installing A Thermal Overload

IF you think about it, it doesn't matter. IT's a complete circuit regardless. But I've always seen overload after the contacts on a contractor. In this case, there's just a on/of switch not contacts.

For some clarification. A breaker protects the wire, primarily in the branch circuit against peak currents. A overload, is a device that protects the motor against sustained high currents to protect the motor insulation from thermal failure.

Large motors with straight line starters usually have a contractor (which is just a big relay) along with a manually or remotely resetable circuit breaker and thermal overloads.

dj1
Re: Installing A Thermal Overload

Spruce, a good place will be between the motor and the switch.

Re: Installing A Thermal Overload
dj1 wrote:

Spruce, a good place will be between the motor and the switch.

I agree, they're usually located in the equipment or the JB mounted on the equipment i.e. garbage disposer, saw, grinder etc.

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