Transfer switch question

[kwired]

I'm not an expert obviously regarding Transfer switch products, but I believe there are separate transfer switches and combination transfer switches.

Without looking it up, some units I believe are incorporated into the main panel, only allowing one position or the other to feed the panels breaker bussing whereas I've also seen others that are simply a secondary enclosure which separately connect into an existing main panel enclosure, many times a lug block is used or a secondary over current protection is used to regulate the potential from the generator onto the breaker buss.

A transfer switch is nothing more than a "double throw switch" that connects a common terminal to the load served and you operate the switch so that you connect to either the utility or to the standby generator. Is designed so that you can never connect simultaneously to both sources.

The "combination" you mention is just a more advanced switch that maybe has one or more of the following: service disconnecting means incorporated, load center incorporated, automatic transferring components incorporated. Simple manual transfer switch is typically nothing more than a double throw switch.

 

[jap]

The ocp for the load side of the transferswitch is either the 200 amp main in the switch when on utility, or the 100 amp or whatever is on the generator, when on standby.
How would the generator be tapped “upstream” of the consumers utility? That’s what the transferswitch isolates.

Not exactly.

Nothing has changed when you are on utility.

Installing the 200a Service Rated transfer switch didn't magically offer protection that you didn't already have.

It's simply a wide part in the road at this point.

When on utility, or on the generator, the existing 100 amp OCPD on the panel remains the the OCPD as was before.

JAP>

 

[jap]

I coined that "wide part in the road" thing from you K-wired,,,, how'd you like that?

JAP>

 

[hillbilly1]

Not exactly.

Nothing has changed when you are on utility.

Installing the 200a Service Rated transfer switch didn't magically offer protection that you didn't already have.

It's simply a wide part in the road at this point.

When on utility, or on the generator, the existing 100 amp OCPD on the panel remains the the OCPD as was before.

JAP>

I disagree, without the service rated transferswitch, the only ocp on utility side you have is at the transformer. The 200 is a much lower ocp than the utility, as the utility transformer is usually way over fused.

 

[LarryFine]

I disagree, without the service rated transferswitch, the only ocp on utility side you have is at the transformer. The 200 is a much lower ocp than the utility, as the utility transformer is usually way over fused.

He's comparing it to the same service before the ATS is/was installed.

 

[jap]

I disagree, without the service rated transferswitch, the only ocp on utility side you have is at the transformer. The 200 is a much lower ocp than the utility, as the utility transformer is usually way over fused.

The 100 amp overcurrent protection that was there before, and, is still there now, is much lower than the 200 amp SE rated Transfer switch.

 

[hillbilly1]

The 100 amp overcurrent protection that was there before, and, is still there now, is much lower than the 200 amp SE rated Transfer switch.

But you were saying nothing changed when on utility, that’s where I disagree. Now you have another ocp before the 100, even though it’s twice as large, it is a change all the same.

 

[jap]

But you were saying nothing changed when on utility, that’s where I disagree. Now you have another ocp before the 100, even though it’s twice as large, it is a change all the same.

I was saying nothing had changed as far as the size of the overcurrent protection.

You were saying without the service rated transferswitch, the only ocp on utility side you have is at the transformer

Not so.

You still have the 100 amp Overcurrent protection even if that protection happens to be at the end of the line.

JAP>

 

[hillbilly1]

I was saying nothing had changed as far as the size of the overcurrent protection.

You were saying without the service rated transferswitch, the only ocp on utility side you have is at the transformer

Not so.

You still have the 100 amp Overcurrent protection even if that protection happens to be at the end of the line.

JAP>

Sorry you took it that way, but that was not what I was saying. Maybe I mistook what you were saying.

 

[jap]

Sorry you took it that way, but that was not what I was saying. Maybe I mistook what you were saying.

We probably did... we're good hillbilly.

JAP>

 

[kwired]

I coined that "wide part in the road" thing from you K-wired,,,, how'd you like that?

JAP>

I don't take full credit, I got that from someone else on this site several years ago when describing what a meter socket typically is. Can't remember who anymore. Think one of the members that is no longer with us though.

And as far as "overload" protection goes yes the original 100 amp breaker still will prevent overload, presuming current is flowing on intended paths. That doesn't mean all NEC overcurrent protection rules are totally in compliance though. For application in discussion here the single service conductors landed in the single 200 amp breaker need to be 200 amp conductors as a general rule and not much for exceptions to that rule other than maybe when only supplying a single load that supplies a motor or similar situations where branch circuit device is allowed to be higher than most typical situations.