Interlock Switch?

[dalola]

Anyone have any experience with these, opinions, comments, etc...

I want to redo my current portable generator back-up system for my house. I'll be getting rid of a my 6 gang 15A transfer switch, so I can get more capacity. Thinking of going the interlock switch route vs. buying a bigger transfer switch. Seems like a better set-up, being able to select anything already in your panel.

I'm not an electrician, just know enough to be dangerous! Any thoughts welcome.

 

[RNeumann]

I guess the interlock has its place. It would be something an electrician would sell to a homeowner on a budget.
If I was said homeowner and doing the change myself for my own place I wouldn’t spend too much for an interlock. I’d write a note about what to do in what order inside the panel and just make it happen.
Of course the automatic transfer switch is the nice and safe setup. It works when you aren’t there but family is.

 

[tc429]

they built a new gas station and dairy queen downtown this year, and in the drivethru lane, cant help but notice a pair of huge manual transfer switches and outlets(inlets i guess) for generator to plug in... so guess even big 400 amp services can do this too, guessing for extended outages, short term, they'll just suffer with everyone else

 

[ruffdog]

I think I read something about balancing the electrical draw on both sides of the panel???

 

[Tractor Seabee]

Cannot help you w/o pictures of your panel and genset with complete info on both. There are many options for the interlock switch mechanisms. Every manufacturer makes them for their line of residential panels. Load shedding can be your headache if your genset is less amps than your panel. I use a secondary emergency load panel with the interlock in the main panel that feeds the secondary panel. Probably the best solution and overall the cheapest and easiest. You may well need to separate the wheat from the chaff as you get responses on this thread.

Ron

 

[ddbackhoe]

Cannot help you w/o pictures of your panel and genset with complete info on both. There are many options for the interlock switch mechanisms. Every manufacturer makes them for their line of residential panels. Load shedding can be your headache if your genset is less amps than your panel. I use a secondary emergency load panel with the interlock in the main panel that feeds the secondary panel. Probably the best solution and overall the cheapest and easiest. You may well need to separate the wheat from the chaff as you get responses on this thread.

Ron

with an interlock, load shedding is the headache because there isn't anyway to do it except conservation through willing participation of the household members. Without a large generator you can't run the electric clothes dryer, electric deep well pump, electric stove/oven, electric HW heater and heat pump/AC at the same time.

Someone I know just had a 22KW propane standby installed. The installers hooked it to a 100lb. tank. I had to walk away from the conversation before I started laughing.

 

[LouNY]

with an interlock, load shedding is the headache because there isn't anyway to do it except conservation through willing participation of the household members. Without a large generator you can't run the electric clothes dryer, electric deep well pump, electric stove/oven, electric HW heater and heat pump/AC at the same time.

Someone I know just had a 22KW propane standby installed. The installers hooked it to a 100lb. tank. I had to walk away from the conversation before I started laughing.

With an interlock you are at your breaker panel switching and connecting your generator, simply flip off the breakers you don't want on or whos load you can't handle. You are the load shedder.

 

[ddbackhoe]

With an interlock you are at your breaker panel switching and connecting your generator, simply flip off the breakers you don't want on or whos load you can't handle. You are the load shedder.

All well and fine if YOU are the only one that does it.

 

[LouNY]

So write up a procedure, use a marker to color breakers or use the labels,
if that's to complicated for someone else to do, they can sit in the dark.
Or spend a bunch of money on an auto transfer and auto start and whole house capable unit
with its associated high fuel cost.

 

[CobyRupert]

Separate issues are getting blended here.

Transferring the source from utility to generator using either a transfer switch, or manually using main and generator breakers (with an interlock or not) is a totally separate issue from a need for load shedding.
(Granted, there are load transfer panels that transfer one branch circuit at a time)

When it comes to load shedding, or a generators ability to power connected loads, there's 2 issues. People sometimes only consider the first:
1. Running load cannot exceed generator's output.
2. Starting load, or surge, usually from motors, must be considered. Motors typically draw 6 times their (full load) running current for a second or so when starting. Whether a generator can "ride through" this depends on a lot of factors:
Example: A generator may be able to easily power (say) 3 motors (say their 10 hp, 5hp, 1 hp), and can start them easily if the 10hp is started first, 7.5 hp second and 1 hp third, but the same genny will fail to start all at once, or even in reverse order because the "surge" from a given motor is adding to a different running "base" load of the other motors, when started in a different order.

Whether the genny "rides" through depends on a lot of factors: its "momentum", how good the governor responds (fast/slow), the torque response of the motor (gas vs diesel vs natural gas are all different), whether generator saturates (just can't provide the required current), etc...