Can a bad breaker affect voltage?

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Wow this reminds me of an old short story about a woman who accidentally put salt in her tea. Everyone came up with ways to remove the salt until a kid cam along and asked why she didn't just pour a new cup.

Take a multimeter, do a voltage reading to ground on the line side of the breaker, and do voltage test on the load side of the breaker. If there is a difference there is a voltage drop.

Regarding old breaker, new breaker, like most contacts, breaker contacts are designed to swipe across each other when they open and close. This wiping action cleans the contact and creates a better connection. New contacts actually need to be cycled under load a few times to get optimum contact. It takes a lot of cycles to damage the surface of contacts to the point of making them bad. Sometimes though it doesn't hurt to cycle a breaker a few times to see if the natural cleaning axpect will correct the situation.


PS, I used to overhaul large fram circuit breakers for a living, so I am not speaking out my butt on this one. (for once):lol:
 
Strathead said:
PS, I used to overhaul large fram circuit breakers for a living, so I am not speaking out my butt on this one. (for once):lol:
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Most are not aware of what you stated, that exercising breakers causes the moving and stationery contacts to rub together. It is not that unusual for the contact resistance to change each time that you open and close a breaker giving you slightly different voltage readings.
 
templdl said:
Most are not aware of what you stated, that exercising breakers causes the moving and stationery contacts to rub together. It is not that unusual for the contact resistance to change each time that you open and close a breaker giving you slightly different voltage readings.
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And under proper load (not overload), the electrical arcing actually creates more surface area of contact, hence lower resistnace under load.
 
Strathead said:
Wow this reminds me of an old short story about a woman who accidentally put salt in her tea. Everyone came up with ways to remove the salt until a kid cam along and asked why she didn't just pour a new cup.

Take a multimeter, do a voltage reading to ground on the line side of the breaker, and do voltage test on the load side of the breaker. If there is a difference there is a voltage drop.
Click to expand...

And throw out that otherwise good tea?


Instead of making two measurements and calculating difference just measure directly from line to load terrminals, if there is any drop it will be exactly the voltage displayed.
 
Just a possibly obvious adjunct to what has already been said: if there is a voltage drop across the breaker, it will be proportional to the current passing through it. If the breaker is on but there are no loads on the circuit drawing current, there will be no voltage drop across the breaker whether it is resistive or not.
 
ggunn said:
Just a possibly obvious adjunct to what has already been said: if there is a voltage drop across the breaker, it will be proportional to the current passing through it. If the breaker is on but there are no loads on the circuit drawing current, there will be no voltage drop across the breaker whether it is resistive or not.
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Yep, the correct way is to measure contact resistance using a micro-ohmeter and compare to industry specs.
 
Thank you for all the responses.

As mentioned, I was thinking about any voltage drop at a breaker, along with circuit length and load from a discussion at another forum.

When I last checked, that op (I think) has decided to install a new circuit. As I may have mentioned, there was no clear indication of the type of building he was in.
He did mention that an additional circuit would be in a 1200 dollar range (so I'm thinking some type of commercial facility).

In that post I mentioned about maybe adding a buck/boost x-former and boost the voltage to his gear, but also mentioned if conditions changed (in the building with possible other tenants or the utility co,)he could potentially boost too much.

As mentioned, I think he is going to install a proper circuit. But check out this self regulating unit. (thank you, Rod Gervais)


http://www.tripplite.com/en/products/model.cfm?txtModelID=3264
 
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