My customer for this job watched in awe as friends and others on the Jersey Shore suffered weeks without power. This wouldn’t happen to them; a well-maintained backup generator provides reliable protection against occasional outages. They wanted generator protection, and I provided a solution to meet the basic needs as affordably as possible.
Although West Philly power outages rarely last more than a few hours, flooding near a transformer, for example, has recently caused multi-day power outages for a block of customers on the Baltimore Ave. business corridor. For an older person living alone, power outage without a generator or other source of backup power can mean major inconvenience, health threats from excessive heat or cold when heaters or AC do not operate, loss of security when alarm systems’ 4-hour batteries fail in a longer power outage, or general loss of independence when any or all of the above happens. Where solar PV is too expensive or otherwise unworkable (requires battery systems and maintenance to provide long-term backup power), a small, critical loads backup generator system can work for many Philadelphia properties (although difficult noise and setback regulations do apply), providing backup power to critical loads like alarm system, refrigeration, heating system, and a few basic lighting fixtures and convenience receptacles.
- Electrical and natural gas connections attach at the rear of the 6kW generator from underground runs
Backup generator systems for homes qualify as ‘optional standby systems’, subjecting them to the minimum requirements of any generator system. Still, the installation must coordinate the load requirements of connected appliances, lighting, and general use receptacles circuits with the capacity of the generator. Connecting too little is inefficient and under-utilizes the generator resource, while connecting too much could dramatically shorten the life of both the generator and of motor loads operated with the compromised electrical power produced when the generator is overloaded.
When considering your critical loads backup needs, start with a list of loads you’d like to run during a power outage. Consider that any appliance using electricity to heat or cool will likely be a heavy load. Motors, especially vacuums and pumps, will also add significant load, and the startup surges they present can be especially problematic for a generator operating near capacity. An electric oven (or even toaster or coffee maker) may be a poor choice of backed-up load in a small generator system, as could be a window air conditioner or pool heater or steam unit in a shower. However, electric for the blower of a gas-fired heating appliance may be a relatively small contribution to total load.
Following are a typical load calculation for verifying generator capacity and critical-loads match-up, and a panel schedule of the resulting system as-built (the combination of some targeted critical loads on multi-wire branch circuits with non-targeted loads necessitated some adjustments to the original plan).
- Spreadsheet load calculation showing typical critical appliance loads and convenience circuits backed up by a 6kW automtatic standby generator
Licensed Electrician Robert Monk Backup generator provides security, independence for West Philly twin Copyright Robert Monk, 2012
electrical testing commercial electrical electrical commercial
No comments:
Post a Comment