Generator - connecting to subpanel

[ollie76]

Morning folks, looking for a little help on our generator electrical transfer system. I consider myself decent with electricity, but the finer points of this system are making me feel stupid.....could use some advice and info.

We recently moved into a home that has a full generator electrical installation already in place. They installed a sub panel right next to the main panel that has an interlock with all the essential circuits powered. Pretty standard installation I believe. The connection on the exterior of the house has in large red writing......"Bonded Neutral".

We do not have a generator yet and are in the process of narrowing one down for our needs, however, this bonded neutral stuff has me thrown off my game a bit. What does this mean?? Does it affect the type of generator we should purchase?

Right now i'm leaning towards a 7500w /9000w max model with the 240v connection to attach to the house. It should be powerful enough, I believe and shouldn't cost me more than $700ish.

 

[catfish500 mark]

The type of generator you are referring to will be ok for things such as lights, a fridge (one fridge) and perhaps a gas fired furnace since that will be a 120 volt item,but it wont handle a central air conditioner system or electric furnace, water heater, stove, clothes dryer and such Amperage draw and startup amps of these things are critical.As far as the bonded neutral goes Ill let someone who knows for sure answer that one.

 

[ollie76]

Yes, I have modest power requirements. Oil fired furnace, lights, fridge, electric water heater, and that's about it.

 

[pattenp]

A house connected generator should have a floating neutral (un-bonded). The only place the neutral and ground are bonded is at the main service panel.

 

[wyliesdiesels]

Since its on a subpanel, it should have isolated neutral.

EDIT: I didnt read close enough to realize that the OP has an interlock. Interlocks are simply a metal bar that prevents 2 power feed breakers being on at the same time...

Both the subpanel and the generator should have insulated/isolated neutrals...This should be fixed...

 

[ollie76]

I do not see a transfer switch, it has an interlock.

 

[sberry]

Electric water heater is not a minor load. I see the size,,, that is a pretty big genset though,,, it will be greedy running a few lights..

 

[sourdough]

Since its on a subpanel, it should have isolated neutral. My guess is tht the transfer switch doesnt switch the neutral so thats why theres a sign. I would change the transfer switch if thats the case...

I do not see a transfer switch, it has an interlock.

I have an interlock on the main panel/meterbase and it doesn't switch the neutral. Is that a problem, wyliesdiesels?

 

[pattenp]

I have an interlock on the main panel/meterbase and it doesn't switch the neutral. Is that a problem, wyliesdiesels?

You're okay.

 

[sublimate]

The neutral should be bonded to ground in one and ONLY one location.
The writing is may be there to tell anyone who's hooking up a generator that the interlock already has the neutral bonded to ground, so the generator should not.
Or maybe it's there to tell you that the generator should be bonded to ground since the interlock is not.
Seems kind of ambiguous, so I'd verify and then make the sign a bit more clear.

 

[theoldwizard1]

Right now i'm leaning towards a 7500w /9000w max model with the 240v connection to attach to the house. It should be powerful enough, I believe and shouldn't cost me more than $700ish.

I hope it runs on LP or nat gas, because it will drink a lot of gasoline or diesel ! Better figure on keeping AT LEAST 20 gallons on hand at all times. Don't forget to rotate your stock !

If you dropped the water heater, you could easily get by with HALF of that power !


When it comes to generators BIGGER is NOT necessarily BETTER ! MY BIL used to run his "camp" on a 5kw generator/ It drank like a fish and was loud as hell. Now he uses a Honda EU2000i and uses acouple of gallons for a weekend.

 

[ollie76]

Fair enough, the water heater is definitely not essential!

 

[wyliesdiesels]

I do not see a transfer switch, it has an interlock.

My mistake, i misread your original post...

I have an interlock on the main panel/meterbase and it doesn't switch the neutral. Is that a problem, wyliesdiesels?

Disregard. An interlock is different than a transfer switch...

The neutral should be bonded to ground in one and ONLY one location.
The writing is may be there to tell anyone who's hooking up a generator that the interlock already has the neutral bonded to ground, so the generator should not.
Or maybe it's there to tell you that the generator should be bonded to ground since the interlock is not.
Seems kind of ambiguous, so I'd verify and then make the sign a bit more clear.

Its not a good idea to guess...

 

[sublimate]

Fair enough, the water heater is definitely not essential!

Say that to your wife after the second day of cold showers...