Does the sprinkler pump in my DC rowhouse cellar need a generator or a battery backup?

The code does not require it, and whether you want it depends on which of three pumps you own. A booster pump on a street supply keeps the heads flowing at plain street pressure when Pepco goes dark, so the backup is insurance on the top floor. A stored tank and pump system has no pressure at all without its pump, so the backup is the whole system. A condo fire pump already has its power arrangement set by the building code and is the board’s job to test. The do fire sprinklers work during power outages article sorts every house; this one is for the houses that landed in a pump row.

Which pump do I have, and what does an outage do to it?

Read the riser tag, or the design sheet in the closing binder, and find the supply line. It says one of four things, and each one behaves differently when the power drops.

The first row is most of the District, and the reason we push for a DC Water service upgrade before anyone talks about a pump. A bigger pipe needs no electricity and no yearly pump test, and the water service sizing article walks through what that upgrade involves. The pump rows exist for the houses where the upgrade is not possible or not enough.

Does DC require the pump to be on backup power?

No. The District adopts NFPA 13D for one and two family houses through the DC Construction Codes, and the standard’s pump section asks for four things: a test connection, a motor rated for 240 volts and wired to the National Electrical Code, an approved disconnect, and a pump kept at least an inch and a half off the floor. Standby power, a generator, and a transfer switch appear nowhere in it, which you can check in the NFPA 13D first draft report that reprints the 2019 edition. The Department of Buildings electrical inspector checks the circuit and the disconnect at the final, and a pump on a plain breaker passes. A 13R condo building is the opposite case: its fire pump falls under NFPA 20, which does require a reliable power source, and that is why the condo row in the table needs nothing from a unit owner except a copy of the last test report.

How often the question comes up is a small number in the District. The DC Public Service Commission tracks Pepco’s average outage time per customer in its annual statistical reports, and the recent figures run around one to two hours a year. Those hours arrive in a summer storm or a winter ice event, which is also when candles, space heaters, and generators running in cellars start fires. The outage and the fire risk show up on the same night.

Battery or generator?

Battery for a booster pump, generator for a tank pump, and the reason is run time. A 13D booster pump only has to run while one or two heads flow, and the standard sizes the supply for a short duration, so a listed battery backup on the pump circuit covers that window and recharges on house power. A stored tank pump is the only thing pushing water, it is usually a bigger motor because it has to lift from zero pressure, and it may have to run while the fire department arrives. That wants a generator with the pump circuit on the transfer switch. Either way the pump itself is a small load, on the order of a sump pump, and the electrician sizes the real number from the plate on the motor.

What to tell the electrician

1. Which breaker feeds the sprinkler pump. It is a dedicated 240 volt circuit, labeled at the panel because the DOB inspector asked for the label. That circuit moves to the transfer switch or gets the battery unit inline.
2. Leave the disconnect at the pump alone. 13D requires it, and the backup sits upstream of it.
3. Keep the heavy up and the riser apart. If the panel is being upgraded at the same time, the heavy up article covers the clear space in front of the panel that the riser may not enter.
4. Test it on backup power. Kill the main, open the test connection, and watch the riser gauge come up with the pump on the battery or the generator. That ten minute test is the proof, and it is what we run at the annual visit if the backup exists.

What it costs, and whose line it is

Two trades, two lines. The pump or the tank is sprinkler work, priced after the flow test rather than guessed in the first estimate, as the pump or tank article explains. The battery unit or the generator circuit is electrical work on a DOB electrical permit, and its price depends entirely on the panel, the distance to the pump, and whether a generator is already in the picture. Ask the electrician for it as its own line so you can see it. Every cellar is different, so the firm number for your house comes from that quote and the flow test, and we will hand you the pump’s plate numbers to give the electrician.

After the power comes back on a pump system

Look at the riser gauge and compare it to the pressure it normally holds. On a tank system, listen for the pump to cycle once and check the tank level. If the house dropped near freezing during a winter outage, walk the rear addition and the cellar pipe before you trust the system, and the freeze protection article says what to look for. Call if the gauge reads low or you hear water anywhere it should not be.