Shared neutrals used anymore?

[winnie]

I got a marked reduction in harmonic current when we switched Fluorescent lighting to LEDs. Was I measuring that wrong. I didn't know that LEDs produced a lot of harmonics.

--
Tom Horne

Like fluorescent lights, LEDs require a driver circuit to function on an AC voltage source supply.

The harmonics of an LED lamp depend on the design of that driver circuit and can be quite bad. However regulations generally require low harmonic current draw.

Jon

 

[hornetd]

Like fluorescent lights, LEDs require a driver circuit to function on an AC voltage source supply.

The harmonics of an LED lamp depend on the design of that driver circuit and can be quite bad. However regulations generally require low harmonic current draw.

Jon

Jon

What may explain why I never saw an increase in harmonic current was that the replacement program was being sponsored by the Electric Utility. It would be in their best interest to be sure that the materials they would except for their program would not include poorly designed driver modules.

 

[hornetd]

No system is perfect, and I am sure there have been sprinkler system discharges without fires. With that said, they are very rare, and sprinklers are very effective with very good 'bang for the buck's, much more so IMHO than AFCI devices.

Jon

Jon

I didn't mean to imply that there have not been accidental discharges from fire sprinkler systems. I was just saying that it takes a lot more to damage or open a head on a sprinkler system than it does to cause a "Nuisance Trip" in electrical system protective devices.

As it happens Australia keeps the best records on the performance of fire sprinkler systems and they go back over a hundred years. In the entire period that they have been keeping such records they have never had a multiple loss of life in spaces protected by a working system. The individual lives lost were from flash fires such as those in flammable liquids or were the victim was too intimately involved in the ignition for the sprinklers to operate in time to save them. One example is people smoking in bed or while asleep on other combustible furniture. Autopsies showed that they died before any open flaming occurred as evidenced by the absence of antemortem burns on the body. No I don't know how that determination is made and I'm fairly sure that I don't want to know.

Fire Sprinklers would have to be nigh on worthless to be of less value than AFCIs. I very strongly suspect that it would do just as much good to install breakers that included Ground Fault Protection of Equipment with a trip point of 30 milliamperes. The United Kingdom uses a device called a Residual Current Detector. That single device protects all of the service, i think, from any ground fault. I'd like to learn more about those.