Thread Number: 41868
/ Tag: 50s/60s/70s Vacuum Cleaners
Hoover Model 51 - AC current through metal body? |
[Down to Last] |
Post# 442271 , Reply# 1   5/26/2021 at 22:45 (1,058 days old) by huskyvacs (Gnaw Bone, Indiana)   |   | |
Checkrate/Likes
 
1    
It looks like it has a new cord put on. Check there first. Mr. Jerry Rigg himself might have missed something, connected a wire wrong, or pinched a wire when replacing the cord. That leads into the next check, inspect any and all original wiring for cracks, breaks, worn spots, or if a wire is being cut into by the body. Also if it has one of those old style screw-down replacement plug ends with the cardboard or plastic insulator disc, make sure those are snug and correctly wired too.
Non polarized appliances and electrical items will be grounded to the chassis on the neutral leg of the wire, and when there is an issue with the hot side being wired into the wrong spot or shorting to the frame, it will send stray voltage through the chassis and anything metal (also happens if some part of the device in question has a damp spot on it) A similar situation on a larger scale for me being that my garage has the wiring miswired backwards at the subpanel, so hot and neutral are reversed. Every outlet is wired correctly, but outlet testers all report back a miswire. Anything with a metal frame and especially vintage power tools will get a bit painful when wearing anything other than rubber shoes. With modern electrically protected appliances and tools, this is no sweat as they are designed to be safe from that happening and divert the stray current to something other than the chassis. But using any older appliances or tools that are non polarized will give you a tingly feeling more or less equal to if you slept on your hand. Nothing too drastic. No need to change the design of the vacuum or add anything to it, as many people have vacuums here this old and older with no electrocution hazard, it's just there is somewhere inside it that is bleeding current that needs to be traced out. Another theory that it could be the armature windings are shorting to the motor housing and motor mount in some way, which is then shorting to the vacuum chassis. If you do have to add anything it would likely be just little rubber grommets under some of the screws. |
Post# 442273 , Reply# 3   5/26/2021 at 23:20 (1,058 days old) by BetaM64 (Avonmore, Pennsylvania, USA)   |   | |
Checkrate/Likes
 
     
Slight correction: When I mentioned the motor has 80v AC going through it, I meant through the frame, not what's being delivered to the brushes and then commutator. The brushes are getting 120v AC. |
Post# 442276 , Reply# 4   5/27/2021 at 01:14 (1,058 days old) by Lesinutah (Utah)   |   | |
Checkrate/Likes
 
     
|
Post# 442277 , Reply# 5   5/27/2021 at 01:27 (1,058 days old) by MadMan (Chicago, IL, USA)   |   | |
Checkrate/Likes
 
     
A megohmmeter would really be the thing for this. You could just test the motor and all the different bits for leakage.
Here's an idea. Bring the machine into your bathroom. Plug it into the GFCI outlet (that you should have to prevent bathroom users from making toast while taking a bath). See if it trips the GFCI just by running. If not, short the metal body to a good ground (use the outlet, plumbing can be unreliable). That'll tell you for sure if, and under what conditions, you are having ground leakage. Remember it's entirely possible the motor windings are shorting to the core. If you're getting 12v, get a car light bulb and try to light it up with the ground leakage. If it lights, you really have a problem - like a partial short. If it doesn't light, it might simply be excessive capacitive leakage. |
Post# 442278 , Reply# 6   5/27/2021 at 01:31 (1,058 days old) by MadMan (Chicago, IL, USA)   |   | |
Checkrate/Likes
 
     
Adding to Les' comment - *does* this unit have a radio noise suppression capacitor? (That's what you meant, Les.) If so, snip that old cap out. IIRC, some vac motors had the cap as almost part of the motor, as opposed to being a separate piece. Like permanently mounted to the motor frame. Worth investigating.
|
Post# 442310 , Reply# 9   5/28/2021 at 01:14 (1,057 days old) by MadMan (Chicago, IL, USA)   |   | |
Checkrate/Likes
 
     
That's what I was trying to tell you. I guess I didn't explain the technical side of it. It's probably all either capacitive leakage or induction, either way, as you put it, current is what matters. And there being no real connection to power, and only minimal capacitance and inductance, the power source (the chassis) has no juice behind it to move current.
Electricity's a funny thing. Anyway, that's why I recommended the GFCI, they trip based on current. The light bulb, too, an incandescent bulb would only light with a considerable current. |