Transfer switch with a 100A subpanel

operagost · 03-01-2011, 11:46 AM

I have 200A service to my basement with a 100A subpanel on the first floor at the opposite end of the house. I need to install a transfer switch that services both the circuits in the subpanel AND two circuits in the main panel. The transfer switches I have seen don't seem to support a 100A circuit. I need to support both because most of the living space is in the subpanel while vital devices like the boiler, sump pump, water pump, and a freezer are on the main panel.

joed · 03-01-2011, 01:35 PM

Sounds like you need a whole house 200 amp transfer switch. I don't know of another way to service circuits in two separte panels.

operagost · 03-01-2011, 01:43 PM

So I'm looking at a $600 switch. Great!

I won't have the money to buy a generator after I get my transfer switch.

wirenut1110 · 03-01-2011, 07:47 PM

Can you move those circuits to your sub panel? If not, you can move those to another sub panel and just parallel 2-100 amp switches.

If your going with a Generac generator, I have 20 of them I'd let go for $75 ea

plus shipping of course.

operagost · 03-01-2011, 11:40 PM

I can't move the circuits from the subpanel unless I'm willing to invest in a lot of copper because they're on the opposite side of the house. I was pondering your suggestion of adding a new subpanel though-- near the main load center, I presume. Since the original subpanel is 100A, must the new one be greater than 100A? Remember, in addition to all the stuff in the subpanel, I have to move circuits for boiler, sump pump, and water pump from the main.

Thanks!

Saturday Cowboy · 03-02-2011, 02:46 AM

the size of one panel never reflects on the required size of another panel. Only the load and calcs demand a certain size

operagost · 03-02-2011, 10:08 AM

OK, then my plan should be based on doing a load calc on my existing subpanel circuits, plus the vital circuits in the main panel, to compare the feasibility (including safety concerns) of using a second subpanel next to a full transfer switch.

operagost · 03-02-2011, 10:28 AM

OK: duh, if I move those circuits to a subpanel that means I can get a cheaper 100A transfer switch. I get it! Well, at least I think about these things before sticking my hands in live circuits!

03-01-2011, 11:46 AM	#1
operagost Member Join Date: Jan 2010 Location: Pennsylvania Posts: 548	Transfer switch with a 100A subpanel I have 200A service to my basement with a 100A subpanel on the first floor at the opposite end of the house. I need to install a transfer switch that services both the circuits in the subpanel AND two circuits in the main panel. The transfer switches I have seen don't seem to support a 100A circuit. I need to support both because most of the living space is in the subpanel while vital devices like the boiler, sump pump, water pump, and a freezer are on the main panel.

03-01-2011, 01:35 PM	#2
joed Member Join Date: Mar 2005 Location: Welland, Ontario Posts: 6,104	Transfer switch with a 100A subpanel Sounds like you need a whole house 200 amp transfer switch. I don't know of another way to service circuits in two separte panels. __________________ Do not PM with questions that can be asked in a forum. I will not respond.

03-01-2011, 01:43 PM	#3
operagost Member Join Date: Jan 2010 Location: Pennsylvania Posts: 548	Transfer switch with a 100A subpanel So I'm looking at a $600 switch. Great! I won't have the money to buy a generator after I get my transfer switch.

03-01-2011, 07:47 PM	#4
wirenut1110 Electrical Contractor Join Date: Apr 2008 Location: Chester, VA. Posts: 789	Transfer switch with a 100A subpanel Can you move those circuits to your sub panel? If not, you can move those to another sub panel and just parallel 2-100 amp switches. If your going with a Generac generator, I have 20 of them I'd let go for $75 ea plus shipping of course.

03-01-2011, 11:40 PM	#5
operagost Member Join Date: Jan 2010 Location: Pennsylvania Posts: 548	Transfer switch with a 100A subpanel I can't move the circuits from the subpanel unless I'm willing to invest in a lot of copper because they're on the opposite side of the house. I was pondering your suggestion of adding a new subpanel though-- near the main load center, I presume. Since the original subpanel is 100A, must the new one be greater than 100A? Remember, in addition to all the stuff in the subpanel, I have to move circuits for boiler, sump pump, and water pump from the main. Thanks!

Transfer switch with a 100A subpanel