Home Generator 101

Pete Stiles of Sir Sparks (Electrical) Inc. (10/10/2008)

We have written home generator guidelines before but have been requested to write a basic guideline for those of you with limited knowledge on the subject.

We are concerning ourselves here primarily, with Florida where the high loads of air conditioning affect the generator requirements. You might consider that to correctly choose a generator size, would be the simple matter of matching it to the amount of electricity used by your home. Unfortunately few things in life are ever that simple and this is one of them.

First off, the maximum requirement (Peak Demand) for electricity, measured in watts, will need to be allowed for, and secondly the type of connected load will need to be considered, as this directly affects the size of generator required. Finally the quality of the generated electricity will need to be adequate to supply delicate equipment such as computers and televisions.

Many smaller Florida homes might be able to make do with an 11KW generator provided it is of good quality, and as a very rough rule of thumb you could consider 1 KW per 100 square feet to be a good approximation. However to be confident that all factors have been taken into consideration it is best to get a professional electrical contractor experienced in generator installations to calculate the size you will require.

For example if you have one air conditioning unit for your home this will require a larger generator than if you have 2 units totaling the same size as the one larger one. No matter what the amount of electricity these units require when running, 3 times more will typically need to be allowed for in order to ensure they start and do not burn out.

Also unless you have a quality generator which carefully monitors and stabilizes the output to a very high degree, you will have serious problems with sensitive electronic equipment.

Should you over-estimate and choose a generator too large then you will experience the following problems.

Excessive initial cost.
Reduced life span of the generator
Excessive fuel costs.

Conversely if you under-estimate, the following problems will arise.

Burned out Air conditioning units
Burned out fridge/freezers.
Brown outs and black outs from the generator.

The type of generator you choose will also greatly affect the final size required, low cost generators of the same KW rating may not actually be the most suitable for your needs. You can read more about these choices at our webpage.

All in all the best way is to roughly estimate the load yourself then call a generator expert for a free in home survey.