Barbara J. Porterfield says my column about fire safety codes and fire alarms recalled to her mind a question that has been raised with the building manager where she works.

The question is, "Why can't we have emergency lighting on the stairs?"

Barbara is also concerned that the building's interior fire alarm will be inoperable if a fire cuts off the normalsupply of power from Pepco. She would be reassured by the presence of an emergency power source.

In some buildings, emergency power is suppled by generators that can operate until their supply of fuel runs out. Other installations depend on batteries -- especially for such limited purposes as burglar alarms, fire alarms and emergency exit lighting.

When the normal supply of power fails, the emergency supply is supposed to cut in automatically. Modern detection systems can use emergency power to trigger burglar alarms and fire alarms, and some send a warning when normal power has been cut.

Barbara says the only answer she's been given to her question is that an emergency power supply would cost money and the landlord will not install one until the law requires it of him (and therefore of all his competitors). A landlord who incurs expenses he is not required to incur puts himself at a disadvantage. If he does not raise his rents he will make less profit; if he does raise rents it will be more difficult for him to find tenants.

So the fair solution appears to be a fire code that puts the same burden on all owners of comparable premises.

Barbara notes: "The Metro fire last spring put us in the dark and many people had difficulty finding their way down the stairs, a frigthening experience. Visitors in the building did not know where the stairs were located. The 'Exit' signs were not lighted.The District of Columbia is behind other localities in enacting adequate safety regulations for public buildings."

Barbara, I have not compared our fire safety code with those in effect in other cities, so I am not in a position to judge whether we are ahead, behind, or on a par with other jurisdictions. But I do know this: The fellow who pays for insurance and never suffers a loss may think the insurance is an unnecessary expense. He may ask, "What good is it if I have never had occasion to use it?"

However, the first time he is injured or his property damaged he'll know what good his insurance was. And I'm afraid the expense of installing emergency power as "insurance" is in the same category.

You might have it on standby for years and never need it. Then one day it saves your life, and suddenly there is no need for anybody to explain to you why emergency power was worth its cost during all the years you didn't depend on it.

Ah, if only there was a way to foresee the future and know in which year it will pay to buy insurance.