400 amp service

[hot wire]

I have a question about a 400 amp service. What the owner wants 1- 200 amp panel normal power and the other 200 amp panel to be generator power with a transfer switch. 1st question whats going to keep from back feeding the normal panel 1 meter base for both panels. 2nd question normal power panel all grounds and neturals tied together in panel. generator panel all grounds and neturals have to be separated right . Have to be bonded together in transfer switch. just making sure every thing is done right thanks..

 

[Dennis Alwon]

You have to install a transfer switch right after the meter than from the transfer switch feed the one panel that is to be served. The transfer switch will keep it from back feeding the other panel. The grounds and neutrals must be tied together thru the first disconnect.

 

[augie47]

I have a question about a 400 amp service. What the owner wants 1- 200 amp panel normal power and the other 200 amp panel to be generator power with a transfer switch. 1st question whats going to keep from back feeding the normal panel 1 meter base for both panels. ..

If properly installed, the transfer switch. It should isolate the 2nd panel from POCO supply thus the 1st panel.

2nd question normal power panel all grounds and neturals tied together in panel. generator panel all grounds and neturals have to be separated right . Have to be bonded together in transfer switch. just making sure every thing is done right thanks..

If we are talking about an automatic transfer switch that supplies the entire 2nd panel, then it should have a main or have a main ahead of it. That does make the 2nd panel a sub panel and separation of neutrals will be required.

 

[Dennis Alwon]

If we are talking about an automatic transfer switch that supplies the entire 2nd panel, then it should have a main or have a main ahead of it.

Why does it need to have the main ahead of the transfer switch? Can you not have meter--transfer switch--- main disco???

 

[hot wire]

The 200 amp panel has a main breaker in it.

 

[augie47]

Why does it need to have the main ahead of the transfer switch? Can you not have meter--transfer switch--- main disco???

you can if the automatic transfer switch is service rated, and if it is, it will have a main. If it's not service rated then it would need a main per 230.2A

 

[augie47]

hot wire, back to basics for a second. are we talking about an automatic transfer switch or a manual transfer switch ?

 

[hot wire]

automatic transfer switch

 

[augie47]

I'll stand by my guns then. 230.2 will not allow a transfer switch ahead of your service disconnect means unless that transfer switch is service rated (an any service rated transfer switch is going to have it's own main)
If this is a "standard" residential set-up with a Generac or similar transfer switch, there will need to be a main in or ahead of that TS.

 

[hot wire]

yep its a 8500 sq ft house this guy is building ill tell him to get one that is service rated i bet its big money hell your building a house like this thats pocket change to him. thanks for your help

 

[ceb58]

yep its a 8500 sq ft house this guy is building ill tell him to get one that is service rated i bet its big money hell your building a house like this thats pocket change to him. thanks for your help

I'll stand by my guns then. 230.2 will not allow a transfer switch ahead of your service disconnect means unless that transfer switch is service rated (an any service rated transfer switch is going to have it's own main)

445.18 Also back up this statement. You may need to provide a load calculation on the 200 service. 702.5 2 A&B The gen set must be able to carry the load unless there are loads that can be auto. shed.

 

[suemarkp]

If he doesn't want a 200A generator, and is willing to manually switch the transfer switch, you can get a 200A Service rated transfer switch for about $400. The one I have in mind has no breaker, so it must be installed immediately adjacent to the 200A main breaker disconnect panel (but the transfer switch is technically the disconnect, and you go 4 wire from there). The two panels and transfer switch would all need to be "grouped".

 

[hardworkingstiff]

yep its a 8500 sq ft house this guy is building ill tell him to get one that is service rated i bet its big money hell your building a house like this thats pocket change to him. thanks for your help

Maybe you should tell him you will handle it (since you are doing the research), mark it up 10% - 20%, and make some money for your efforts (or make the business you work for some money).

Your warranty won't cover customer supplied equipment. (let the customer know)

 

[tom baker]

you can if the automatic transfer switch is service rated, and if it is, it will have a main. If it's not service rated then it would need a main per 230.2A

There are ATS that are service entrance rated without no main. I have one on a 200 amp 277/480 service. I don't like this as the ATS is always hot and no way to deenergize. The solution is a 200 OCD ahead of the ATS, increasing the cost...

 

[augie47]

Tom, What manufacturer ? I'm not doubting you, I would just like to research it.

 

[hot wire]

Ive never seen a breaker on a transfer switch. So what i need to do set the meter, 200 amp breaker or dissconnect ,transfer switch then go from the transfer switch to the panel. the owner went and ordered the switch he got a manual transfer switch. I dont know whats going to happen when the inspector does his thing the owner not getting a generator right now hes going to use a 8 k.w welding machine which i know doesent put out 200 amps which is the panel size were feeding.The owner did say the switch he got was service rated..

 

[augie47]

Ive never seen a breaker on a transfer switch. So what i need to do set the meter, 200 amp breaker or dissconnect ,transfer switch then go from the transfer switch to the panel. the owner went and ordered the switch he got a manual transfer switch...

sounds like it will be a "memorable" job that large a house with that type owner input usually is

I dont know whats going to happen when the inspector does his thing the owner not getting a generator right now hes going to use a 8 k.w welding machine which i know doesent put out 200 amps which is the panel size were feeding.The owner did say the switch he got was service rated..

Since the TS is manual, there is no "load calculation" requirement. If it is a DT manual switch, there's a good change it is service rated. The mfg info tag inside will tell you normally.

 

[suemarkp]

If you already have 200A main breaker panels, the transfer switch can be the disconnect (it just has to be immediately adjacent to that 200A MBR panel). If not, and you want to buy a 200A disconnect and a 200A MLO panel, that will work too but cost more. 200A residential main breaker panels are about the least expensive type there is since so many are made.

 

[LarryFine]

If you already have 200A main breaker panels, the transfer switch can be the disconnect (it just has to be immediately adjacent to that 200A MBR panel).

And, it still has to be service-rated since it's the first thing after the meter.