What are the pros and cons between these two systems? I am trying to learn both so I can decide. Thanks.

The interlock kit is cheaper but may not be available for your particular panel.  

I would prefer the transfer switch myself.

I got the interlock kit which is half of the price of a tranfer switch.  However, you need to be smart about how many circuits to have on based on your generator capacity.

Why do you prefer the manual switch?

I had an Interlock on my old house, it was fine.  Sold the house and it passed inspection with no issues whatsoever, so no worries there.  

I need to do something here on the new house before next hurricane season...

It really comes down to how big a generator you have. If its big enough to run everything go with a transfer switch. If not, figure out what your going to run with it and get an appropriately sized generator panel.

Unless you have a generator larger than 30KW (125A, max branch circuit size), go with the interlock kit, it is cheaper and more versatile.

If you have a panel that there is not an interlock kit available for, consider replacing the panel. Interlock kits are available for most quality panels and if there isn't an interlock kit, there is a good chance the panel in question should be replaced anyway.

Now that interlock kits are available, I don't see much value in the little 6-10 circuit manual transfer switch kits. They limit your options and cost more than an interlock kit.

the interlock kit gives you great flexibility, I can run anything in my house, but not all at the same time.
I can run all the normal stuff, fridge freezer some lights, etc.
OR, I can run my central Air and cool the house off, I could run my elec water heater, etc.

A transfer switch and exterior plug will run you $300 - $400 and then you have to have it installed by an electrician which asked to be paid basically as much as the transfer switch and plug.  I had an electrician install my interlock, a 30 Amp breaker and a cord long enough to connect to my generator for $425!

if
a) you can't make two adjacent breaker spaces available at the top of your panel,
or
b) there is no interlock kit available for your panel,
or
c) you can't afford to get a new suitable panel installed,

then you'll need to use an adjunct transfer switch.

ar-jedi

i think you are referring to whole-house transfer (line side) switches, not branch circuit (load side) transfer switches.

ar-jedi

I opted for a manual transfer switch primarily for ease of use by my wife. The six circuits on my transfer switch are clearly marked, and all my wife has to do is decide which circuit(s) she wants to power, and throw a single switch for each. She doesn't have to touch the main panel at all to throw the mains or shut off undesired circuits. It couldn't be simpler for her, and that makes it more likely for her to use the genset if I'm out of town.

Our six circuits are designated as follows:
-Furnace blower (LNG)
-Water heater blower (LNG)
-Deep freeze/workshop/cable modem, Router, network switch, and wireless
-Kitchen GFCIs/lighting/fridge/range fan (LNG range and oven)
-Master bath lights/fan/GFCI
-Master bedroom and select area lighting and outlets

We can also plug the washer and gas dryer into the deep freeze circuit if desired.

Also, since none of the above circuits need to be run continuously or concurrently, we can get away with using one of our smaller gensets. Lastly, we have a secondary cordset to the transfer switch that comes from a modest (440Ah) battery bank and Xantrex Trace inverter charger. The bank allows us to stretch our stored fuel, as well as eliminate our nighttime noise footprint. The battery bank can be expanded, and I have an additional 220Ah worth of capacity that can be added in about ten minutes. That only becomes necessary on the coldest winter nights when the furnace is working harder than usual to keep the house warm.


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I am an electrician and I have installed every kind of system from wind solar to a partial manual transfer. Up to 500kw.

If you have an old main panel finding an interlock kit may be difficult and if you build your own it might not pass an inspection when  you sell.

I have never been a fan of automatic transfer switch's unless you have the generator to allow it to switch over with everything running as on Christmas day with all the heat and cooking equipment going full speed.

I have nothing on my house and do not have any big generators but may do so in the future.

During Ike we put a ten kW Miller welder generator on my mothers house.  She was bed ridden and living alone as per her wishes.  We had day time nurses but she could see no reason to have help at night and would quickly run off any night time help we hired.  We knew she needed ac to survive and we tied the 10 kW into her 400 amp service with two 50 amp breakers and no interlock kits.

This is the worst of situations and being that me and my brother both master electricians would do the transfer if needed which it was not, she was only out of power 3 hours.  we got by.

It would have been nice to have had an automatic transfer switch with a 20- 30 kW generator on her house.  But the cost and the amount of use it would get and the chances of it not working when you really;y need it are reasons not to go for it.

I like the idea a of a full size manual transfer switch if you can afford it.  You can use any size generator or swap generator if need be.


Power goes out you get your generator out of the garage run your cord up to a recessed male plug on the side of the transfer switch start it up warm it up, turn off your load and then switch the transfer switch.  Then you bring up the load as needed and to fit your generators capabilities.

You can run on any size generator or switch generators to economize.  Or have the full size generator          go out side turn it on and flip the transfer switch.

The system I hate the most is the partial house auto transfer switch.  You never seem to be able to cover all the needs and either overload the generator causing it to stall or you do not have what you need on the emergency panel.

One other thing to consider is how are you going to pay for the fuel.  During Ike 4-5 dollar gas was what we thought at the time high.  You could easily see 10 dollar gas and even a 10kw partially loaded will run 10 or more gallons a day.  Spending 100-200 a day on fuel to keep a bunch of old freezer burned meat  cold is no bargain.  But I live in the south  where it does not get killing cold very often.

My thoughts run to the minimal.  If you can take the heat down here just get enough to run the fans and water well.  If you live up north get a wood burning system or a furnaces that requires only blower motor electricity.  Most of us would be better off throwing the freezer stuff away on the 2nd or 3rd day.

Not at all. An interlock kit works by using a backfed branch circuit breaker to supply the generator feed to the panel. Since the NEC maximum branch circuit size is 125A that it the largest capacity you can have using an interlock kit. 125A @ 240V = 30KW.

This stuff is not brain surgery and many people are quite capable of doing the installation themselves for either type of transfer setup.

This is the primary advantage of the little 6-10 circuit individual transfer panels, simplicity of operation for novice users.

Regardless of the type of transfer system, even a fully automatic standby system which can still have faults that need to be addressed, I have the following recommendations:

- Install inexpensive battery backup emergency lights to illuminate the main panel, transfer switch, and generator areas. This way the user does not need to be wrestling with a flashlight while trying to operate the equipment. Emergency lights are ~$50 these days.

- Print very clear diagrams and instructions, preferably in color, and place in sheet protector holders adjacent to all equipment0.

- Perform at least quarterly training drills with novice operators to develop skills and confidence.

This is exactly why I recommend the interlock kits over the little 6-10 circuit transfer panels, and the beauty of an interlock kit which is essentially an asymmetric transfer switch. Your generator feed can be any size from 15A to 125A so you can readily use a 30KW generator. The backfeed breaker also is not required to match the generator size as it is functioning as switching duty, not circuit protection. The circuit protection at the generator is what protects the wiring up to the backfeed breaker. This means that you can install an interlock kit with backfeed breaker and wiring sized for the maximum load, and you can connect any size generator you want with the appropriate cable to connect to the inlet box. Maximum flexibility at the least cost.

The kits are available for most newer breaker boxes.  People who have 400 amp services with two breaker boxes make it a little more complicated.  Unless you have electric heat most people can get by with 10 kW and a lot less.

I am remodeling a house now to move into next year and the last thing I will do is rebuild the service.   I will be moving the service off the house {due to trees} and about 20 feet away to the side of the property.  It will be built on 8x8 galvanised H beam.   I will install a 400 amp transfer switch at that time.  Why Because I can.
I am converting the appliances to all gas on everything I can.   I could go to a 200 amp but it had a 400 so I will keep it you never know what gas prices will do and now it is wired for all electric and all gas.


I have watched folks spend a great deal of money on gas, diesel and propane trying to keep up their comfort.  If you can take the Houston Texas  heat this is not necessary.

I'm still not sure why a lot of people have 400A service, I guess some just think bigger is always better. Unless you have a house that is truly mansion sized it just seems that 200A is plenty. I have 200A service and I have a pretty well equippend shop on a 125A sub running a big TIG welder, plasma cutter etc. with no problems, and in the house electric dryer, water heater, heat pump, etc. with no issues.

As for maintaining comfort, a small window or portable A/C stored in a closet can be pulled out to keep one room comfy while operating on a smaller generator. What I do if need be for an extended outage is to just move out to my camper where heat or A/C on generator is not an issue.

THIS is what im planing on installing on the new house.

That's certainly interesting, and expensive. Not sure what the utilities would think of it, I know at least some require meter sockets with built-in lever bypass which that thing doesn't seem to have.

double check on that first.

your POCO owns the meter.  the adapter sits behind the meter.  if the POCO says no go, it's no go.
this has been the day 1 problem with that method of generator interconnection.

you have to call Generlink AND your local POCO, and get everyone on the same page.
http://www.generlink.com/get_state.cfm

ar-jedi

already been taken care of. my local power co has installed several of these for different people. thats where i found out about them.

good deal, proceed!  

ar-jedi

i have several friends that work at the CoOp as well as a family member that works in the office. i hear about all the installs they do. LOL. we have had several tropical storms/hurricanes and heavy snow/ice storms that have knocked out power for days and even weeks depending on where you live in my area so generators have become hot items around here in the last 5 years. i will say the "were" installing them, i guess i should check to make sure they are still doing it. nothing has really changed other than they have gone to digital meters over the last year.

I doubt that would go in the Centerpoint service area {around Houston}  It looks like it is set up for a ringless can but requires a ring type meter.  You still can have a manual bypass can but any downward load on the meter can jaws is a bad Idea to start with.

the only place I see the use of this device is for Ranch water wells and they are easy to transfer with a plug at the pressure switch.

for the price an interlock kit is much cheaper and easy to install and gives more options with less hassle.  I would like to see the failure rate on these guys.  I see no way to manually  bypass or feed through with it as with most auto transfer switch's.


If this is for a new house you have the chance to do this right.  The room is there and it will cost very little labor compared to a retro fit job.  Spec panels with a interlock kit or a full size auto transfer switch.