Which Circuit Breaker to use 3KA or 6KA?

[Justloadit]

I have noticed that quite a few contractors seem to be cheaper in their quotes on installations.

What I have noted is that they quote using 3KA circuit breakers, which are much cheaper than the 6KA breakers.

So the question is, what breakers do you use in your installation, and why?

[Isetech]

You need to know what the fault level is in the DB at that point of installation.

In our part of town the fault level is generally around 450 amps so a 3 KA breakers for domestic installations is fine.

When you start working in commercial and industrial DB's, then you need to know the fault level at that point in the DB, by measuring the fault level or doing the calcualtions.

Just because an 800 amp DB has a 10 KA rating on the label doesnt mean the entire DB is 10 KA, there are ways of reducing the fault in the DB, but that should be left for the people who know what they doing or are qualifired to type test the DB.