How do I replace power cord on vintage power tools

[Simple Sam]

As noted in my recent thread, I picked up a Cman grinder and drill press. Both of them need their power cord replaced due to the insulation cracking and exposing the wiring. Both are non-polarized, two prong plugs.

I checked Lowes and see they have two options; a polarized two wire cord and a three prong cord http://www.lowes.com/ProductDisplay...elshp=req&rel=nofollow&cId=PDIO1#BVRRWidgetID or http://www.lowes.com/ProductDisplay...gId=10051&cmRelshp=req&rel=nofollow&cId=PDIO1 . Which one would be better and how do I install it?

I pulled off the cover of my grinder and saw how the cord was originally attached. The black wire goes to the on/off switch and the yellow wire goes to a doohicky (see photo). Photo shows bad plug, bad cord, and doohicky that yellow wire is plugged into.

If I use a polarized, two wire plug, do I hook it up the same way; black to the switch and other color to the doohicky?

If I use a three wire cord, where do the three wires go?

I'm not an electrician and have never had even the most basic training in electricity so I don't really understand the concepts that others may find pretty basic so if you have any basic info, I would appreciate it. Thanks,

 

[dittle fart around]

Get a 3 wire grounded plug. Drill and tap for a 8-32 brass screw and land the green ground wire directly to the case. Black goes to the switch and the white wire replaces the yellow.

 

[Outlawmws]

And get the right crimp connectors and a crimper and do the job right. DON'T splice the wires.

The plastic insulator may be able to be re-used, or you can buy a new one. DON'T skip it; it is there for a reason.

 

[dankicksass]

Your yellow wire is probably hooked a thermal overload cutout, for what it's worth. As long as you put it back together like you found it, should be no problem. That bushing should transfer to the new cord, but if you can't get it on there are more in the electrical aisle. There's also a Skil branded replacement cord you'll find in Lowes or Home Depot with a bushing and stretch guard that fits most tools, but it costs twice as much as the generic cords.

 

[BrokewrenchLS1]

Two-prong cord would be fine; power tools are designed for double-insulated cords without a ground for a reason, as they're safer than a case-grounded design. A case-grounded tool should be fine, but a double-insulated cord is going to be safer, as the tool was designed so that no single fault condition could cause an unsafe condition, and the tool was designed to meet that requirement without a grounded case.

I'd personally go with something a little heavier than 16-AWG, but that's just me. And definitely get the strain relief - it's essential for a safe tool.

 

[Outlawmws]

Brokewrench, Not in this case. His grinder is not double insulated; this is an older grinder, if you looked at his DP/Grinder threads. Made before grounded cords and double insulated cases. Metal case, little plastic in the design.

Cord design has little to do with a tool being double insulated, other than choice of 2 or three wire. A Double insulated tools became practical when plastic cases overtook metal, which is not the case here. Adding a grounded cord will bring the grinder up to current code/UL specs for the grinder, but does not make it double insulated.

http://en.wikipedia.org/wiki/Double_insulated#Class_II

 

[larry_g]

Two-prong cord would be fine; power tools are designed for double-insulated cords without a ground for a reason, as they're safer than a case-grounded design. A case-grounded tool should be fine, but a double-insulated cord is going to be safer, as the tool was designed so that no single fault condition could cause an unsafe condition, and the tool was designed to meet that requirement without a grounded case.

I'd personally go with something a little heavier than 16-AWG, but that's just me. And definitely get the strain relief - it's essential for a safe tool.

The above is totally wrong. If you look at the equipment that the OP is talking about it is old stuff made long before insulated cases were thought about. I would also suggest that the cordset be replaced with a three wire and ground as suggested above.

lg
no neat sig line

 

[BrokewrenchLS1]

Didn't realise it was such an old grinder...double-insulated doesn't apply here then, but grounding to the case could still cause some issues with some single-fault situations.

It's not going in for compliance though, so whatever works.

 

[Simple Sam]

Thanks for the answers. This is what is so great about the internet; a wealth of knowledgeable people with expertise to share.

I guess I'm off to the hardware store tonight. I need a power cord, crimp connectors (have crimper but will probably solder as well), tap (never used one before), and 8-32 screw.

 

[Simple Sam]

Well that was easy. I ended up getting a three prong plug and it was easy to replace. I didn't end up tapping and installing a bolt; instead, I used the bolt that attaches the trim plate to the base. I was able to hide the wire behind the trim plate so you can't see it. I'm not sure I will be able to skip the drill and tap on my drillpress but that is a longer term project; the grinder I wanted to get into service ASAP.

 

[Outlawmws]

Well that was easy. I ended up getting a three prong plug and it was easy to replace. I didn't end up tapping and installing a bolt; instead, I used the bolt that attaches the trim plate to the base. I was able to hide the wire behind the trim plate so you can't see it. I'm not sure I will be able to skip the drill and tap on my drillpress but that is a longer term project; the grinder I wanted to get into service ASAP.

Technically, I believe the ground is supposed to have a dedicated ground screw. I think to insure metal to metal contact, and not paint to metal and insulated...

 

[Simple Sam]

"Technically"? Or only a fool would do it that way? I could pretty easily remove the paint; it wouldn't be visible and then there would be direct contact between the wire and the base. I'm hesitant to try tapping and installing a bolt as it would require me to acquire new tools and new skills; I can see it turning into a $20 hole in my $15 grinder.

 

[larry_g]

Technically, I believe the ground is supposed to have a dedicated ground screw. I think to insure metal to metal contact, and not paint to metal and insulated...

Technically it is supposed to have its own screw, but I was always taught that it was because the next person to take the cover or attachment off may reinstall the attachment and not the wire. Functionally it will work if it has good contact.

lg
no neat sig line

 

[osborn.ozzy]

and to think I have about 50lbs of cords that I have cut off broken stuff ive thrown away or got from stuff in the garbage. Ill mail you a few just for S&H

 

[barnale]

I also have some power tools which do not work any more because the power cord is broken. I did not replace it because I am not sure if I can do this. So I decided a while ago to use a power rental and simply rent the power tools I need. So I do not have to repair the old ones and I do not need to buy them when I need them. Maybe I should prospectively ask a friend if he can help me to repair the power cord.

 

[sometoyotaguy]

Old computer power cords work pretty well. Just cut off the power supply connector.

 

[Underdog]

Old computer power cords work pretty well. Just cut off the power supply connector.

Just be sure the wire size is appropriate for the tool. Some appliance cords are on the small size.

What I do is if the tool will be used a lot is to get a cord from a appliance/tool repair store and pick up a heavy 16 -14 awg tool cord, much better quality than HD/Lowes, usually Made USA also.

 

[Davefr]

Old computer power cords work pretty well. Just cut off the power supply connector.

Yes, but they're almost always 18 AWG. That's pretty wimpy for all but the smallest amperage power tools.

 

[toolmiser]

Some of the older "computer" cords are heavier gauge wire. The thing I've noticed is that the coating is rubber, but more vinyl so if it gets cold where you are, they aren't very flexable.