Circuit Breaker selection????

I am always a little disturbed when people ask these sort of questions. The answer is a simple one and if you don't know it you are not qualified to perform the electrical work (especially given your previous posts).

I am hardly going to offer advice that I believe will put either the poster of the question or others that may come into contact with the posters work in potential danger. That would be very unprofessional of me (and others). I advise you to get an electrician or other suitably qualified professional to perform the work for you.

To clarify that a bit better for the Original Poster, selection of protection devices is a key component of any electrical installation and should only be done by professionals. But it is also something that is very specific to the location you are in, meaning there are codes and governances that vary in each country, state even municipality. So you need a professional IN YOUR AREA who knows how to do this safely, correctly and legally.

I am sorry to say sir, your comment is not good either. This is a forum where we learn. We are all people in the practical field. May be this is the debue for the person. We cannot imply our own predictions about somebody's qualification. If the person is ignorant then its your duty to expound the matter more than what He needs.

I think you misinterpreted my comment. The point I was making is that the
"proper selection" is NOT just a purely engineering endeavor, it also involves adherence to local codes and laws in a given country. It would be irresponsible for me to explain how we do it here, because that might be illegal where he is!

Point noted but this is not the cross-stitching or painting forum. The answer to the original post is actually simple and the original poster should know it or at the very least, know where to find it. Remember, as a professional our job is also to protect others. I have answered other questions like this, generally with comments suggesting that they refer to the motor or circuit breaker manufacturer documentation (the answer is in there and should be the first place to look).

Here is a question for you, would you answer this hypothetical question posted on CR4.....

" Hi all, need plans for mercury dispersion and vaporisation system. Also diagram of electric detonator."

The answer is clearly no in this extreme case. The key point is that in the end it comes down to a personal judgement call - what do I think the poster would do with this information if I give it to him/her and will it be used responsibly and not cause harm.

Hopefully this short post clears up a few things for you and gives the original poster a better idea on where they should look for this information if they have not found it already.

I agree with the last two comments....Motor protection should be sized by a professional.....Given this some information for you to know.....Typicall start-up in-rush current can be up to 5 to 6 times the normal running current of the motor...and depending on the ineteria of the load being started the duration of this start-up current varies.....Hence a need to evaluate the I2T requirements to implement proper motor protection....

Please consult a competent person on this issue before proceeding with ann installation.

Vow, Vow. So many comments. It's quite true that such sort of things have to be done by a professional. But how does the professional come into being? Nobody is born professional. He acquires professionalism from various sources. Look , I am also new in the field, so I need help from the experienced guys. I may not do things myself. I just watch the others do that. But the more I go into it, I look for more sources to acquire practical knowledge. This forum happens to be one of those sources.

u r right

May i ask how did u guys become professional? Ofcourse u ASKED! If someone doesnt know how to select a circuit breaker, what do they do? they consult ofcourse from you people.

Regarding this query, i would like to know how to chose a circuit breaker for this purpose just for my knowledge.

May i ask how did u guys become professional?

By obtaining the suitable Electrical qualifications from a University, trade School, distance learning centre, etc and obtaining suitable hands-on training in such areas as electrical safety, first aid, local electrical wiring codes and regulations, legal requirements, etc.

If someone doesnt know how to select a circuit breaker, what do they do?

Call an electrician normally. The average person, home owner etc can change a fuse themselves legaly and safely (depending on local electrical codes and regulations for more information) but should generally NOT perform such work as three phase wiring and circuit protection as was implied in the original post. My answers to current questions (generally) include more information to help make this distinction clearer and to also request more information from the poster to determine if the question is a general interest question.

Regarding this query, i would like to know how to chose a circuit breaker for this purpose just for my knowledge.

An internet search of "circuit breaker selection" and "sizing a circuit breaker" produced numerous answers, alternatively this question has been answered numerous times on CR4 since this thread from 2008. You could try the search function on CR4 on the right-hand side of the screen.