Electricians...Generator House Hookup. Transfer switch vs. interlock kit.

Alright GregH and others:D Thinking about finally pulling the trigger this winter on a generator backup for my home (ductless mini splits, a few lights, the TV, hot water heater ((electric)) ). Some people say a transfer switch is the way to go, others swear by the simplicity and lower cost of an interlock kit. The latter worries me because don't I have to proactively monitor the circuits to ensure I'm not overloading the generator? Anyways, I'm wondering what your thoughts are on this before I purchase. I'm probably going to purchase and install the hookup before I buy the generator for what it's worth.

 

Just do a manual transfer switch. Easy and cheap. Unless you have frequent outages, all you have to do is go outside and flip a switch. It's just wires hooked into a box, the most basic ones don't have anything electrical other than the wires.

No idea what an interlock kit is.

As for monitoring circuits, do the math on your max, and make sure you don't overload it and you provide enough room for expansion. A switch won't stop it from overloading, a breaker box will though.

 

I have the loads calculated already (need ~6500w/8000W surge).

Here's a basic diagram showing an interlock kit. It's essentially tapping into a new dedicated breaker rather than having circuits coming from the breaker into the transfer switch:

 

I'm about to replace my electric panel and I'm going with the interlock kit. I like having the option of picking ANY circuit in the house to power. Those transfer switches don't give me enough options.

My last power outage, I ran my genny plug through my dryer vent and plugged into the dryer and backfed my panel. I powered all the necessary lights in my home, tv, fridge, and freezer. When my pressure tank would get low, I'd kick off the freezer & fridge breaker and turn on the well to refill my pressure tank. Hot water lasts a while but I'd do the same thing when it starts to lose it's heat.

 

Finch, that's a major code violation (unless I'm reading that wrong). If you forget the main breaker switch (and even if you don't...there can still be current that leaks by) you can put utility workers in danger.

 

Well you know which way I suggest you should go. I could not be happier Matt.


http://forums.bowhunting.com/water-...-up-installing-generator-transfer-switch.html

 

That would depend on where you live as far as the code violation. If you forget the main breaker you will trip out the generator instantly because of the draw from your neighbors.

 

What is the difference between me shutting off the main and someone using the interlock kit? Obviously the main and generator breaker both can't be "on" at the same time but that's the only difference, right?

 

Now that we've bought a house, this project is on my list of things I'd like to do.

 

I agree. Also (and this doesn't make it right) but the lineman should never be injured if they are doing their job correctly. PPE, working in between grounds, etc. I'm sure lines are backfed all the time from ppl using generators and not knowing what they are doing.

Matt, what did you mean exactly about current still leaking by? That was my point about my method (which is temporary until I can replace my panel and get the interlock) vs using an interlock. There are the same thing except the fact that the main can never be on while the generator is.

 

Don't have time right now (kids working on something, so I took a break), but here's one incident that such caused such a result.

Lineman Killed By Generator Back Feed - Victim Helping Restore Power in Alabama - Electric Energy Online

Will post back later.

 

Finch, one removes the element of human error which is why is illegal in most states to backfeed a panel without an approved switch or safety interlock. I looked up the exact code (NEC 702.6). From my understanding, in theory with an interlock and or backfeeding and shutting off the breaker prevents backfeeding, but because you aren't cutting ALL conductors (just hot and not netural bond), there's a RISK of still backfeeding if there's improper grounding at the panel and/or generator.

After doing more reading, I think I've already convinced myself to just go with a transfer switch.

I was hoping GregH would chime in. He's the expert:D

 

MGH im really confused, Im not an electrician but had to work alot with it over here so I know the general things. But it seems like you are and you know what codes to go to, so why are you asking us? I would think that you would have friends who would know more about this, or were you just wanting a forums opinions?

Not trying to come off as a jerk, I just thought i might be of use and it turns out, nope it's stuff I can conceptually understand but can't comment on!

 

Ok, I'm just asking here but are those interlocks approved by the NEC?

 

I'm far from an expert I do consider myself handy, and do most of my work myself, but I'm not a licensed contractor nor am I an electrician. I learn by doing and A LOT by researching and reading. I know a few on here are contractors and/or electricians, so they may have some opinions on the subject as well. I'm a member on a few DIY forums and have asked the same question over there. Just trying to get some opinions on the advantages and disadvantages of the two systems.

As for the not directly backfeeding a panel with a generator, I learned that a while back when talking to my dad's friend who is an electrician (btw, yes I asked him this question, and he said either way is fine and he doesn't have a preference). I knew it was against NEC code, I just didn't know what code (again, I'm just a guy fumbling his way through this stuff):D

 

From what I read initially, yes. Then I read excerpts of the NEC, code, and it looks less black and white.

Read for yourself - > electrical - Are generator interlock kits permitted in residential applications? - Home Improvement Stack Exchange

It's on a information exchange, but there are excerpts on that page taken straight from this section in the NEC code.

 

Haven't been on much because my home computer is down right now.

I'd go with the transfer switch, manual or automatic.

 

I'm also toying with the idea of a whole house propane unit backup system. I'm just concerned about how little they get used and if/when it would help the resale value of the home at all.

 

Most of the large propane back units will automatically start up and do an exercise session of mabye 10min. once a week. It keeps the battery charged and things working good.

If I didn't lose power really often and it were me I would go the much cheaper route and just buy a portable genny and a transfer switch.

 

Id say that's the way to go......... price Generacs.
I think the no worry hassle free will pay off first time you would have to drag out and set up a generator and keep full of gas.
not to mention no worry if away from home.

Id say it would help resale of home.
If not just take the darn thing with you to new house.