Not quite sure what is meant about "Power Limit."  So, I'm going to take a poke at it to see if I can help.

My house has 200 AMPS.  How do I know this?  The meter on the outside of my house is a 200 AMP meter and the Main Breaker panel in the house has a 200 AMP main breaker with cut on/off switch.  Each AMP [AC] can push 120 watts of power.  So, a 200 AMP Main Breaker Panel can push 120 x 200 = 24,000 watts.  By the way, the unit of measurement for Power is watts.

24,000 watts is my "Power Limit" for my house.  However, I have other appliances in the house that REQUIRE power to maintain a comfortable living.  I looked up my HVAC (Heating, Ventilation, Air Conditioning) unit to find that it requires 30 AMPS to start and then settles down to 20 AMPS after approximately 5 to 10 seconds.  I also have lights in the house [all with LED bulbs], clothes drier, washing machine, refrigerator, microwave,  modem, router, switch, stereo receiver and 2 televisions.  All of these other appliances require approximately 60 AMPS of constant power if they were all on at the same time.  

80 AMPS is what is required to run my house for the most part.  Some of you might say it is 90 AMPS because of the 30 amps instead of 20 amps needed to start up my AC unit.  However, I have a heavy duty capacitor installed [approximately 10 feet between the unit and the main panel] to store electricity to reduce the surge on my other appliances.  That leaves 120 AMPS left over for mining.  120 AMPS x 120 WATTS per AMP = 14,400 WATTS of power allowed for mining.

If I had 16 S3's [which I do] at 355 watts each, I'm already using 5,680 watts of my allowed 14,400 watts.  This leaves 8,720 watts for S4's.  That means I can get six (6) S4's and be fine with my "power limit."

So, when someone asked you, "What is your power limit?" I think that is what they were referring to.  I could be wrong about this but thought I would give it a shot.

Someone also said, "Why limit yourself?"  The reasoning behind that question is because you can always convert your Bitcoin to USD to pay for your power used and still have USD left over [at least at present price of BTC and difficulty].  You may only want to convert what bitcoin is needed just to pay off your power bill and leave the rest of your bitcoin alone to wait to purchase more rigs when bitcoin is worth more USD.  I believe bitcoin will be worth much more before too much longer.

Not sure if you live in an apartment, single family home, etc...?  You need to go to your power meter that the power company reads to determine how many amps it is.  It may not actually say how many amps.  You may have to write down the model number of the meter and look it up on the web.  Then you need to find your main breaker panel and find out how many amp main breaker panel switch you have.  I can answer any other questions you may have after you have found out the answers to those two things.

I hope this may have clarified some things for you.

EDIT:


I suppose we could use "how much we can pay for" but it actually has limits.  If you have a 200 AMP meter on the side of your house [Like I do], you are presently limited to 200 AMPS or 24,000 WATTS of power minus wattage needed to run HVAC, washer, drier, etc.  You might can get another meter installed on the side of your house to gain more watts.  However, this will come at a cost you may not be willing to pay.  This may include the power company burying [As in my case] another cable from the transformer to the side of my house and install another 200 AMP meter.  I'm not sure if they will charge me for the cable and to bury that cable or not.  More than likely they will charge me.

As far as your statement, "...for which I don't want to do;" my question would also be, Why Not?  You can always convert the BTC that is needed to pay your power costs into USD on Coinbase.  That is why someone asked earlier, "Why not?"