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to discharge or not to discharge capacitors

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marlboro

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Discussion starter · #1 ·
is ok not to discharge a dual capacitor before replacing it? it was mentioned (i forgot were)that since main power to outside unit was turned off already, capacitor will discharge by itself.
 
#2 ·
A charged capacitor can stay charged for quite a while. Best to discharge it properly (use a resistor of around 100 ohms, not the tip of a screwdriver) and play safe. No-one needs to get a shock.
 
#3 ·
You have to discharge it to test it. Unless it's exploded and then a fairly good chance it's discharged. I use an insulated screwdriver or insulated needlenose to discharge.
 
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#4 ·
It will disharge by itself provided it is still properly connected to the motor.

If a wire happened to come off one of the terminals while the unit was in operation the cap will still be holding a charge even if all power is disconnected.

It has happened!

Best to attempt to discharge just to be safe.
 
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#5 ·
Fabrk8r said:
It will disharge by itself provided it is still properly connected to the motor.
Click to expand...
This is the truth

I replace hundreds of capacitors a year and I have never discharged a single one, I also have never been shocked by one.
Also, you don't need to discharge it to test it as long as all the wires have been removed and there is no power feeding to it.
 
#6 ·
Fabrk8r said:
It will disharge by itself provided it is still properly connected to the motor.

If a wire happened to come off one of the terminals while the unit was in operation the cap will still be holding a charge even if all power is disconnected.

It has happened!

Best to attempt to discharge just to be safe.
Click to expand...
This has been my experience.
 
#9 ·
I always discharge with my nut driver or screw driver before disconnecting a cap. Got bit once when I first started this business and never want to repeat the experience. Always err on the side of safety when dealing with something that has the potential to hurt/kill you. It's just good practice.
 
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#10 ·
Start capacitors with high microfarads normally have a bleed resistor across the top of them to discharge themselves. I have never been zapped by a run capacitor and I dont think that its possible to get hit by one because it would have happened to me by now.
 
#11 · (Edited by Moderator)
This guy has some interesting videos. Does anyone know if he's a member of this forum?

Here's a video he posted on youtube about discharging capacitors on RTUs.
 
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#12 ·
CoolingTower36 said:
Start capacitors with high microfarads normally have a bleed resistor across the top of them to discharge themselves. I have never been zapped by a run capacitor and I dont think that its possible to get hit by one because it would have happened to me by now.
Click to expand...
I've seen it happen. I like your thinking though, I've never seen anybody get hit running a 4-way stop sign either.
 
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#13 ·
CoolingTower36 said:
Start capacitors with high microfarads normally have a bleed resistor across the top of them to discharge themselves. I have never been zapped by a run capacitor and I dont think that its possible to get hit by one because it would have happened to me by now.
Click to expand...
Then you just been lucky.
 
#14 ·
CoolingTower36 said:
Start capacitors with high microfarads normally have a bleed resistor across the top of them to discharge themselves. I have never been zapped by a run capacitor and I dont think that its possible to get hit by one because it would have happened to me by now.
Click to expand...
LOL....It hasn't happened to me so it cant happen. Good thinkin. How hard is it to stick a screw driver across the terminals to make sure.I have had plenty of them discharge when doing this. You keep thinking that and I guarantee you will get hit.
 
#15 ·
Fabrk8r said:
This guy has some interesting videos. Does anyone know if he's a member of this forum?

.
Click to expand...

He's member, but under a different name here.

His video, doesn't show everything, and can be misleading to those that don't know what he is omitting.


Since he has DIY videos, I removed the link from your post.
 
#19 ·
A 2 watt 20,000 ohm resistor is the proper way to discharge a capacitor. Protects you and the capacitor.
 
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#20 ·
I do quite a bit of work with VFD's and larger single phase motors, I have been bitten one time by a 30X370 cap from 1 HP condenser fan motor that had open windings...No factory resistor across the terminals....:gah:

I will tell you that if you don't at least ground one side of the cap when doing repair work, it is only a matter of time before you have the crap shocked out of you. The shock may not permanently hurt or kill you, but if you have the knee jerk reaction that most people have, you could really cut the living crap out of yourself on some nice jagged or rusty sheet metal, seen it happen...:yes:

Don't be a lazy schmuck, discharge the damn caps...:deadhorse:

GT Jets
 
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