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In Reply to: RE: Not Safe posted by Tweaker456 on August 09, 2016 at 09:34:57
In theory, it is slightly better if the caps are not at the component, but at the breaker box.
However, the bottom line is that it is still dangerous.
Jon Risch
Follow Ups:
Guys, let me tell you cautionary tale about amateurs and electricity.
Push pull system, friends advise him to place a 50uF motor run capacitor across the line and neutral (240 volts, 50 hertz.
Does so and is highly impressed with the new sound.
He then fits a second one - even better. As always, more is better so in goes third one.
Here we use a Ring Mains system where each half of the ring can support 3 kilowatts. The ring main wiring burns out right back to the main board.
Where two units are plugged into the same socket, that burns out completely.
The fuss over it being dangerous to self, is a bit overplayed.
Regards to all.
JohnR
I don't think the type of capacitor the OP is talking about are run capacitors.
An AC run capacitor is designed to be hooked up across the mains, at the motor, continuously. Don't try that with a start capacitor though.https://en.wikipedia.org/wiki/Motor_capacitor
Edits: 08/12/16
I have edited my OP on this issue. I shouldn't have been able to since it is so old and there have been responses. Don't know what's up with that. I did not edit the language in the original post. Aerovox dry type (and oil type) lighting caps are continuous use caps. The tutorials say that shock risk is not a concern with across the line caps and there is a fire danger upon failure in short mode. You can read the exact language in a number of spots. Don't understand the leakage thing in relation to across line caps in failure as a short. Self healing would reduce that risk along with being fused. There are other types of caps that have increased protection from internal shorts. Even Type X safety caps can catch fire and are or can be described as self extinguishing. Maybe they should not be used either? Zero risk with the use of capacitors across the AC does not exist. Tweaker
Edits: 08/12/16
I have edited my OP on this issue. I shouldn't have been able to since it is so old and there have been responses. Don't know what's up with that.
//
Posted by Tweaker456 (A) on August 13, 2016 at 08:29:04
Up until recently there has always been a time limit and once someone replied you could not edit the post. The edit and delete go away. I'm not quite sure what you are talking about. If it were not the case anyone could just change anything they said and it would be unworkable. No discussion would have any merit.
Again,The AA program does not have a time limit or a limit after a response has been posted. I think after a thread has been archived the post can not be edited.
As for the specific caps you are using it would have helped if you would have provided a Link to a site showing the specs for the caps you have.
There are some lighting caps that are made to be connected across the line. There are others that are made to be placed in series with the winding of the ballast. (LC, Inductor/capacitor, circuit.)
http://www.lampholder.net/lampholders/wp-content/uploads/2016/02/high-pressure-sodium-ballasts-wire-diagram.gif
I believe in all cases the cap is there mainly to correct PF, Power factor.Some AC capacitors not only are used to correct PF but also will raise the line voltage. You might want to check the line voltage at the equipment you are using the caps on without the caps connected and then with the caps connected.
Edits: 08/13/16 08/13/16
Up until recently there has always been a time limit and once someone replied you could not edit the post. The edit and delete go away. I'm not quite sure what you are talking about. If it were not the case anyone could just change anything they said and it would be unworkable. No discussion would have any merit.
When I saw I had made a mistake. It's the Subject line you can't edit.
I just edited my previous post.
Check the edit date below the page on my previous post.
Of course you must login, upper right hand corner of the page, before you can edit a post.
You can not delete a post after someone has posted to your post. You can not delete a post after 24 hours.
Signing is is a good idea. Why didn't I think of that. Now my OP in this thread can be edited but no longer deleted. Looks like you can't edit after a certain amount of time.
So I signed in and at first it looked like I couldn't edit post. Now everything seems to come up with edit delete. Many times before when this has happened and I tried to edit a post it would say nice try and wouldn't let me do it because it was already answered or to old?? Why should you be able to completely change a post after it's been out for awhile or was already responded to??
"Where two units are plugged into the same socket, that burns out completely.
The fuss over it being dangerous to self, is a bit overplayed."
Even potentially starting a fire in your house as you posted? Amateurs and electricity are a bad combination and your statement at the end of your post I perceive as irresponsible.
FYI... I am a qualified electrician and have over 25 years experience in industrial electric systems and instrumentation. I understand the theory behind using shunting caps to reduce noise. I have been required on several occasions to install them to put a band aid on a problem. I certainly would not attempt what was advocated by the OP. I would even be hesitant to install Al Sekala's device as mentioned by another poster.
Safety concerns aside, the filtering approach achieved by putting massive shunt caps by themselves is not going to be that much compared with using a much smaller cap in a more optimal filter topology. An RC or CLC topology could allow reduction of the sizes of these multi hundred u farrad caps to only a few mics each at most and probably achieve even better noise filtering. I wouldn't necessarily recommend CLC's for less experienced amateurs due to the inrush current/ back emf over voltage problem that could break downstream semiconductors. RC's seem like they could be a very effective approach a careful amateur might safely have good success killing noise with, however.
Besides, best case scenario this type of filtering can only address differential mode noise. I'm not entirely convinced some common mode filtering along with all this diff mode filtering wouldn't go a long way for a lot of folks looking to quiet down the ac.
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