dcsimg
Self Help Forums

Go Back   Self Help Forums > Repair > Electrical - Existing Home
Register FAQ Members List Calendar Today's Posts

Electrical - Existing Home Electrical Repair / Remodeling Ideas / Problem Solving Solutions

Reply
 
Thread Tools Display Modes
  #1   IP: 12.38.17.22
Old October 6th, 2003, 12:17 PM
Anonymous Anonymous is offline
Senior Member 'Self Help Master with Distinction'
 
Join Date: Sep 2002
Posts: 1,999
Default Generator Transfer Switch for Split 400 amp Service

Hello. I have 400 amp service that's split at the meter into two SE cables each feeding adjacent 200 amp main service panels installed in my basement. I want to install a generator transfer switch, but, unfortunately, the circuits I want to supply with the generator are not all in one panel. In addition, there is not enough slack in the branch circuit cables to simply swap circuits between the two main panels. I've ruled out a single 400 amp switch, so my options appear to be: (a) Install a conduit between the two main panels, or (b) Install junction boxes to allow me to swap circuits between the panels. I've looked through the NEC, but I don't see anything that would prohibit either option. Am I missing something? Is there a better solution to this situation?

Thanks.

Bill O'Connell
Reply With Quote
  #2   IP: 130.76.32.144
Old October 6th, 2003, 01:00 PM
imported_suemarkp imported_suemarkp is offline
Senior Member
 
Join Date: Jul 2003
Location: Kent, WA
Posts: 206
Default

This is a tough one, as I've just been through this myself and with less forethought. What I did was run a 100A feeder from a main panel to a transfer switch which then goes to a 24 slot 100A subpanel. I've then relocated every critical circuit to that subpanel. This could be an option depending on the paths your cables go. But if I were doing this over again, I'd pick a different way.

To me, the preferred way is inserting a 200A transfer switch in front of one of the 200A panels. This keeps the switch as Service Equipment and makes dealing with the generator ground/neutral bonding easier. But as you noticed, you have to get all your critcal circuits moved to one of the two panels. You will also have to reroute service conductors which is more complicated and you can't run them inside the house very far (also need to pull the meter or get the service de-energized if you have a CT). You could also put a transfer switch in front of each 200A panel, but you'll need to spend another $300 on a second switch. Note that the transfer switch must be adjacent to the main disconnect if the switch has no internal overcurrent protection. This is probably the type that you want, as if it does have integral overcurrent protection, your main panel will become a subpanel and the ground and neutrals must be separated. This could be challenging if the existing panel has ground and neutrals sharing a common bus.

The conduit between panels could be an ugly solution, but if there are only a few circuits in the wrong place it won't be too bad. The J boxes make your service look poorly planned, but again it works but gets ugly if there are too many circuits to move. Other than what I listed above, I don't see any more choices.

Some issues to consider when buying your switch:
1. Will it have integral overcurrent protection and therefore become a main disconnect?
2. Is it 2 pole or 3 pole? Having 3 switched poles gives you more choices for dealing with neutral/ground bonding. Mine has a 3'rd section for switching 3 poles, but only came with switch guts for 2 poles so the neutral can not be switched.
3. You may want to become familiar with NEC 230, so you don't violate any of the Electrical Service rules, especially main disconnects and their placement.
__________________
Mark
Reply With Quote
  #3   IP: 68.49.37.110
Old October 6th, 2003, 06:37 PM
Anonymous Anonymous is offline
Senior Member 'Self Help Master with Distinction'
 
Join Date: Sep 2002
Posts: 1,999
Default

Mark,

Thanks for your insight and recommendations. The 200A switch would be nice, but there's quite a jump in price from 100A to 200A; not sure I can justify spending more than half as much as the generator for the switch alone.

I'm thinking that conduit connecting the two main panels will be less ugly than j-boxes, so I'm leaning towards that option.

Bill
Reply With Quote
  #4   IP: 148.78.243.122
Old October 8th, 2003, 05:25 PM
Wgoodrich's Avatar
Wgoodrich Wgoodrich is offline
Super Moderator

 
Join Date: Sep 2002
Posts: 7,451
Default

If you installed two two hundred amp trasfer boxes in line with the service conductors then you have unlimited choice of entire house to run on generator as long as you do not exceed the maximum amp rated overcurrent device on the generator required not to exceed 115% of the maximum capacity of the generator. If you generator is big enough to run say 40 amps you could run anything in the home one at a time such as electric water heater, a/c, electric range, chosing what is to run at any given time. Teh two 200 amp transfer boxes would allow an unlimited choose in your house to be generated.

If you only install one 200 amp trasfer box now for one panel you may later add the second one as you can afford it and still have the entire house choice to generate not to exceed capacity of generator at any given time.

If you opt to the cheaper 100 amp then you will have to spend more money to create a generated emergency sub panel. You are not allowed to run a 100 amp transfer box to a 200 amp panel. This means the extra cost of a sub panel for your emergency circuits that you will have to move from main panel to that emergency panel. This greatly limits what can be generated if you make this choice. You get what you pay for.

Good Luck

Wg
Reply With Quote
  #5   IP: 12.211.121.250
Old October 8th, 2003, 06:02 PM
imported_suemarkp imported_suemarkp is offline
Senior Member
 
Join Date: Jul 2003
Location: Kent, WA
Posts: 206
Default

Bill - what type of transfer switch are you buying and what does it cost? From Harbor Freight Tools, http://www.harborfreight.com item 42163, you can get a Cutler-Hammer manual transfer switch rated at 200A for $299. Two of these would be $600. I would expect your generator to be costing much more than $1200, so these prices aren't too bad.
__________________
Mark
Reply With Quote
  #6   IP: 68.49.37.110
Old October 9th, 2003, 07:10 PM
Anonymous Anonymous is offline
Senior Member 'Self Help Master with Distinction'
 
Join Date: Sep 2002
Posts: 1,999
Default

wg - Thank you for your reply. You're absolutely right, switches on the line side of the main panels gives maximum flexibility chosing gen-powered circuits and eliminates need for subpanels. I *thought* I had done thorough research and was seeing $900+ for 200A switches, but Mark seems to have done a much better job and found $300 200A switches, so I may need to rethink my plan.

Mark - That's an amazing price. I saw those on C-H's web site and the list is $1360, so I thought no way. How can HF sell them for $299?! I wasn't even looking at 100A, I was was looking at Gen-Tran PowerStay 301060 30A for around $325. As you pointed out before, it only switches the hot conductor so I may have neutral/ground bonding issues inside the gen. I stretched my budget to get a Yamaha YG6600DE (6000 watt) so I didn't think I could do the bigger switches. I thought the watt meters on the G-T might be helpful balancing the phases, and the 30A seemed adequate for a 6KW gen.

Bill
Silver Spring, MD
Reply With Quote
  #7   IP: 12.211.121.250
Old October 9th, 2003, 10:38 PM
imported_suemarkp imported_suemarkp is offline
Senior Member
 
Join Date: Jul 2003
Location: Kent, WA
Posts: 206
Default

I bought the 100A switch, and a co-worker bought the 200A switch. Seems like a quality product to me, and they are much larger than I expected them to be. There is something strange about how electrical equipment is priced. I'm speculating that residential equipment is subsidized somehow, as inductrial stuff is about 10X more expensive. The Harbor Freight prices seem reasonable to me, but anything over $500 seems like way too much. I hope no one pays list price for this stuff!

I don't know if you researched 400A panels. The cheapest I found was around $500 for a panel with an aluminum bus. But at Home Depot, you can get a 200A panel with 6 circuit breakers that you probably need for $79. If you subtract out the breakers at your cost, the panel is about $40 which seems like a give away to me. I bought a third 200A panel for the breakers, a spare main breaker, a spare door/cover, and one of the lugs that allow larger wires to be used on the neutral bus. That double large neutral lug item itself costs about $10 by itself if you need it.

So I now have 400 amps with 64 breaker slots at a panel cost of $160 ($240 if you count spare parts and all included breakers). All I gave up was some wall space that is required to be dedicated for electrical use anyway.
__________________
Mark
Reply With Quote
  #8   IP: 68.49.37.110
Old October 10th, 2003, 05:07 AM
Anonymous Anonymous is offline
Senior Member 'Self Help Master with Distinction'
 
Join Date: Sep 2002
Posts: 1,999
Default

Mark - Good to hear from someone that actually bought the CH switch from HF that it's good quality. At 80 lb., it certainly passes the weight test .

I'm having trouble envisioning your final configuration...what happened to your original 100A subpanel? Now you have a 100A switch, 100A subpanel, and three 200A panels? I'm confused.

On the 400A panel, I currently have 23 single-pole and 2 two-pole breakers in one main panel; 18 single and 2 two-pole in the other, so there's no way I'm getting all that into a single 400A panel, right?

Bill
Reply With Quote
  #9   IP: 148.78.243.122
Old October 13th, 2003, 01:33 PM
Wgoodrich's Avatar
Wgoodrich Wgoodrich is offline
Super Moderator

 
Join Date: Sep 2002
Posts: 7,451
Default

200 amp panels are normally about 160 dollars each. parallel 200 amp panels make a 400 amp service.

200 amp transfer box should cost about 300 dollars each. One 200 amp transfer box for each 200 amp main service panel would cost about 600 dollars total for the two transfer boxes in parallel allowed by the NEC for a 400 amp service with parallel 200 amp main service panels.

When you jump to 400 amp you jump to industrial grade about 4 times the money than two 200 amp residential panels and transfer boxes.

While a 6 kw generator will only carry about 30 amps it will run all your lights in your house or it will run your water heater if electric or it will run many a/c units as well as furnaces one at time.

You are allowed to connect a 6 KW generator to the two parallel transfer boxes at your service. Your overcurrent device required to serve your generator at your generator protects it from overload.

If it were me I would buy a 60 amp 12 kw generator. I also do not recommend a gas driven generator. The carborator will be plugged up when you really need it in an emergency.

I would spend the money buying a PTO driven generator that will run from your garden tractor or an old farm tractor you use all the time and keep running when needed when mowing etc. during normal use.

If you have no tractor available then I would choose an LP driven motor that is less likely to lacquoer up when not in use.

Remember that chain saw you bought new and 6 months later it would not run after only one week end use. Same problem Carb lacquered up.

Just my thougts.

Wg
Reply With Quote
  #10   IP: 12.211.121.250
Old October 13th, 2003, 07:33 PM
imported_suemarkp imported_suemarkp is offline
Senior Member
 
Join Date: Jul 2003
Location: Kent, WA
Posts: 206
Default

I have two 200A panels dual fed from a 400A meter base. One of the 200A panels has a 100A breaker that goes to the transfer switch. This switch then goes to a 100A sub panel. The third 200A panel is not installed and only provides spare parts.

Yes, no way to get more than 42 slots in a lighting and appliance panelboard. So you must have the two 200A panels like you have, or would need a single 400A panels with a subpanel off of it to create enough slots. The dual 200A is the way to go in my opinion.
__________________
Mark
Reply With Quote
Reply






Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Service panel in bathroom (garage) *guest Electrical Code - USA 7 May 30th, 2009 09:10 AM
Lighted Switches *budspwr@ntelos.net Electrical - Existing Home 1 December 12th, 2003 11:43 AM
New Service *JOHNNY Electrical - Existing Home 0 December 12th, 2003 11:36 AM
400 amp wire and conduit size twigpig Electrical - Existing Home 1 May 26th, 2003 06:44 PM
3 way switch Anonymous Electrical - Existing Home 3 November 3rd, 2002 07:50 AM


All times are GMT -4. The time now is 11:46 PM.


Powered by vBulletin® Version 3.6.7
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
© 2002 - QuinStreet, Inc.
http://www.selfhelpforums.com