Adding a ground to a vintage 2 plug jointer?

[remagenman]

I acquired a 1953 Rockwell Delta jointer that only has 2 plugs for the power cord. It works fine but wondering if this requires a ground plug to be installed for safety?

Thanks.

 

[The Cobbler]

yes , add a new cord with ground , attached to the motor and switch box

 

[wyliesdiesels]

I acquired a 1953 Rockwell Delta jointer that only has 2 plugs for the power cord. It works fine but wondering if this requires a ground plug to be installed for safety?

Thanks.

do you mean prongs?

yes i would change the cord and plug to 3-wire. Is it 120v or 240v?

 

[BreeStephany]

I acquired a 1953 Rockwell Delta jointer that only has 2 plugs for the power cord. It works fine but wondering if this requires a ground plug to be installed for safety?

Thanks.

Replace the cord with a quality SOOW insulated / grounded cable and cord cap. Drill & tap the metal enclosure where the cord enters the first junction point with a 10-32 tap and use a 10-32 screw and a ring terminal on the ground to bond the ground to the case.

If the cord for the jointer goes to a switch junction first and then to the motor, you should also replace the cord between the switch and motor with cord with a grounding conductor and bond the motor to the junction box via the grounding conductor and not just the case of the equipment, especially if the motor has rubber vibration dampeners on the mounting bolts.

For most shop equipment, I just buy SOOW cable and a cord cap. If its a power tool being used on a job site, I prefer to use a manufactured cord whip with a molded cord cap, as some OSHA inspectors won't pass cord caps on hand power tools.

Just my two cents.

 

[nadogail]

Replace the cord with a quality SOOW insulated / grounded cable and cord cap. Drill & tap the metal enclosure where the cord enters the first junction point with a 10-32 tap and use a 10-32 screw and a ring terminal on the ground to bond the ground to the case.

If the cord for the jointer goes to a switch junction first and then to the motor, you should also replace the cord between the switch and motor with cord with a grounding conductor and bond the motor to the junction box via the grounding conductor and not just the case of the equipment, especially if the motor has rubber vibration dampeners on the mounting bolts.

For most shop equipment, I just buy SOOW cable and a cord cap. If its a power tool being used on a job site, I prefer to use a manufactured cord whip with a molded cord cap, as some OSHA inspectors won't pass cord caps on hand power tools.

Just my two cents.

The above was very well written.

 

[pattenp]

I don't suggest SOOW because it is 600V and is bulky. The SJOOW is 300V and is commonly used on corded wood working equipment.

 

[remagenman]

Replace the cord with a quality SOOW insulated / grounded cable and cord cap. Drill & tap the metal enclosure where the cord enters the first junction point with a 10-32 tap and use a 10-32 screw and a ring terminal on the ground to bond the ground to the case.

If the cord for the jointer goes to a switch junction first and then to the motor, you should also replace the cord between the switch and motor with cord with a grounding conductor and bond the motor to the junction box via the grounding conductor and not just the case of the equipment, especially if the motor has rubber vibration dampeners on the mounting bolts.

For most shop equipment, I just buy SOOW cable and a cord cap. If its a power tool being used on a job site, I prefer to use a manufactured cord whip with a molded cord cap, as some OSHA inspectors won't pass cord caps on hand power tools.

Just my two cents.

Thanks and I'll have to google what a lot of you mentioned means but wouldn't a 12AWG power cord from Lowes work just as well?

Also, how did these old cord plug connections exist as a standard without a grounding plug? Less electrical harm back then? And how has it lasted this long with just a 2 prong plug?

Also, were the jointer is located I have a 220v outlet available and the motor can be wired for 220v also, is there an advantage? Here is a pic of the motor emblem:

 

[wyliesdiesels]

Thanks and I'll have to google what a lot of you mentioned means but wouldn't a 12AWG power cord from Lowes work just as well?

what kind of power cord?

Also, how did these old cord plug connections exist as a standard without a grounding plug? Less electrical harm back then? And how has it lasted this long with just a 2 prong plug?

Also, were the jointer is located I have a 220v outlet available and the motor can be wired for 220v also, is there an advantage? Here is a pic of the motor emblem:

back when that was made, there was no grounding or grounded receptacles so.... less electrical harm back then? no actually there was more harm.... thats why the grounding system was adopted. to prevent harm from electrical systems....

If you switch it to 240v operation, it will run cooler and may start easier...

 

[PoorUB]

If you switch it to 240v operation, it will run cooler and may start easier...

I have to ask, why would it run cooler? On 120 volt is sees 7 amps run through two windings in parallel. On 240 volt is sees 3.5 amps run through two windings run in series. Each winding sees the same watts no matter how they are wired.

 

[Stuart in MN]

For a 1/2hp motor there's no advantage to running it on 240vac. Leave it 120vac, and then you can plug it in anywhere.

 

[Norcal]

For a 1/2hp motor there's no advantage to running it on 240vac. Leave it 120vac, and then you can plug it in anywhere.

At 1 1/2 HP it can go either way but smaller motors it's better off 120V for the versatility.

 

[rlitman]

I have to ask, why would it run cooler? On 120 volt is sees 7 amps run through two windings in parallel. On 240 volt is sees 3.5 amps run through two windings run in series. Each winding sees the same watts no matter how they are wired.

Well, 7A will see twice the voltage drop when running than 3.5A. As the voltage drops motor current rises and power factor drops, which increases resistance (heat) losses. Does this matter? It depends. As the current goes up and extension cord resistance increases (with length or smaller gauge), it may start to become an issue. But at 1/2HP on a decent sized cord in a 20A circuit, I doubt it will make any difference).

 

[FredWanaker]

Before you add your ground, use a voltmeter to measure the voltage between ground and the frame. Then flip the plug over and check it again. If it is lower one way, use that one to make sure you get the neutral wire right. I have seen many old appliances, radios, tools etc, that leak more in one plug configuration than the other. It all depends on how the original device was wired back in the 1950's, and if the system was properly isolated. I can remember in the 70's having to make sure they were plugged in one way or the other to prevent that tingle when touching them. Not all devices will show a difference in leakage, but some will.

 

[PoorUB]

Well, 7A will see twice the voltage drop when running than 3.5A. As the voltage drops motor current rises and power factor drops, which increases resistance (heat) losses. Does this matter? It depends. As the current goes up and extension cord resistance increases (with length or smaller gauge), it may start to become an issue. But at 1/2HP on a decent sized cord in a 20A circuit, I doubt it will make any difference).

Well, I would assume the wiring to the motor is adequate so that doesn't play into the mix. You could try run it on 240 volt and a 22 gauge wire and it wouldn't work either so lets just assume the wiring is correct. Either way you are running the same watts through the motor so I don't see the difference.

I hear people make that comment to wire the motor for 240 volt instead of 120 volt and truly would like to know what I would make a difference, because I don't see that it does.

 

[mike93lx]

I would leave it 120v.

For a cord, I'd probably grab an extension cord or the right length and gauge and cut the end off. I like molded on plugs.

 

[nadogail]

I would leave it 120v.

For a cord, I'd probably grab an extension cord or the right length and gauge and cut the end off. I like molded on plugs.

You could also use the cord set sold for garbage disposals. They will be heavy enough but might be a little short. For tools and equipment mounted on wheels I prefer longer power cords.

 

[Jim greengo]

Or just plug it into a gfi protected circuit.

 

[Meursault74]

I would leave it 120v.

For a cord, I'd probably grab an extension cord or the right length and gauge and cut the end off. I like molded on plugs.

You could also use the cord set sold for garbage disposals. They will be heavy enough but might be a little short. For tools and equipment mounted on wheels I prefer longer power cords.

I've used those grounded power cords that come with computers, monitors and various electronics and cut the end off that plugs into the device. I know they're good only up to 10 amps though. I have numerous spares. I've never actually bought one. They come with nearly everything.

I have one of those cords on my vintage 1940's table saw. I grounded the motor with it as well. I measured my current draw. It runs about 4 amps.

 

[PoorUB]

There are hundreds of choices for cords and at 7 amps 14 gauge is more than enough.
I would buy a 25 foot all weather extension cord and lopp of the female end and use it.

 

[nadogail]

It’s the Female end of the extension cord that I would cut off to make a power cord for a tool with the remainder using the molded plug on the Male end.

 

[Norcal]

There are hundreds of choices for cords and at 7 amps 14 gauge is more than enough.
I would buy a 25 foot all weather extension cord and lopp of the female end and use it.

With a 7A load a 16 gauge cord would do just fine.