Need help deciding on manual transfer switch vs. interlock switch

I've been getting a lot of contradictory information from my local electrical contractors on my way to get an estimate for installing a manual transfer switch between my generator and my breaker panel. I need to clear the picture and hope someone can help me:

I have an off-the-rack Lowe's bought "Troy-Built" 5500W portable gasoline generator and want to install a transfer switch so I can by-pass the house's main breaker and run the generator to supply temporary juice when undergoing extended loss or power.

So far I have gotten the following advice (and prices):

  1. Install a 6-circuit manual transfer switch for 0
  2. Install the same as above for ,200 to ,800, depending on what's involved
  3. Told my generator cannot work with a transfer switch
  4. Told I'd be better off using a Square D Interlock kit instead of the
6-circuit transfer switch so I can use the entire existing house breaker panel and manage the load myself, not being restricted to 6 circuits (My breaker panel is a GE and supports Square D)
  1. Told *never* to use GE Interlock (or any other brand) and stick with manual transfer switches instead, whether 6- or more circuits

All the above info provided by 5 different state-certified, licensed contractors that operate in my local area.

So, I have learned nothing except I need independent advice.

Any help will be greatly appreciated!

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The panel interlock kit is the way to go if you can get one that is Laboratory listed or recognized for use in your panel. They are far less expensive then transfer switches, allow the use of any load that the generator can carry, and they assure break before make operation like a transfer switch. I have installed several of these for clients and I find there low cost and simplicity of operation a very strong selling point.

Some Authorities Having Jurisdiction (AHJs) want to see all transfer switches have common pole transfer mechanisms were the same pole connects each conductor of the load to the two sources of power. Their position is based on the idea that now individual pole can be in two places at once so there is no failure condition that can cross connect the two power sources. This position is seen as extremist abuse of authority by most practicing electricians including myself. When faced with this position I ask for a written order and then I call their boss. So far that has taken care of it.

Some utility companies do not like interlocks because they are mounted on the panel's cover and if the cover is removed then so is the interlock. My reply is any safety system can be bypassed if you put enough effort into it. Unless the utility is also the AHJ for electrical code enforcement in your area their legitimate interest in your homes wiring stops at the demarcation point that has been established by your state or provincial public utility regulatory agency.

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Tom Horne, Electrician

Thanks for the prompt reply.

The contractor that suggested the interlock switch came by to give me an estimate and have a personal look at what I have. He verified that the panel (26 years old) is GE (not Square D) and told me he would install a GE-brand interlock switch *inside* the panel and placed just below the main breaker. It could not be tampered with or removed without taking the panel face completely off. He would then supply an inlet box for the generator mounted on the exterior of one my garage's side walls, supply a 25' 30 amp generator cord, and provide grounding for the generator. According to him (and another local wholesale-only contractor, the interlock switch is code approved and permitted by the county).

Most likely, this is the way I'll go, given the flexibility it offers vs. the 6- or 10-circuit transfer switch.

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What sort of price did he give you for this and did he break it down any? Thanks.

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