Wiring To Electrical Sub Panel


  #1  
Old 12-02-07, 06:06 AM
J
Member
Thread Starter
Join Date: Dec 2007
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
Question Wiring To Electrical Sub Panel

would like some help on safely wiring a 2000w modified sine
wave power inverter to a sub panel.the power inverter's input
voltage would be a 12v deep cycle battery.the inverter has
overload,thermal,and short circuit shutdown.it also fused with
a 30 amp fuse.any and all info.would be greatly appreciated!:
 
  #2  
Old 12-02-07, 08:15 AM
J
Member
Join Date: Sep 2002
Location: welland ontario
Posts: 8,038
Received 515 Upvotes on 420 Posts
Use a transfer switch same as would be used for a generator.
If this is not ever going to be used for line power and only be supplied power from the inverter then use a cord from panel to the inverter with the proper matching plug.
 
  #3  
Old 12-03-07, 03:17 AM
J
Member
Thread Starter
Join Date: Dec 2007
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
thank you for the prompt reply! so there is no safe way to
hard wire the inverter directly to a 30amp breaker in the sub
panel?
 
  #4  
Old 12-03-07, 03:55 AM
core's Avatar
Member
Join Date: Jan 2007
Location: Des Moines, IA
Posts: 1,048
Upvotes: 0
Received 0 Upvotes on 0 Posts
Perhaps you should explain exactly what it is you are trying to do? Are you trying to backfeed the entire subpanel from your inverter? A subpanel which is also likely supplied by grid power at the SAME TIME?

Honestly I don't know what you're asking because you haven't provided any details... it can't be what I just guessed because that's ludicrous.
 
  #5  
Old 12-03-07, 04:49 AM
J
Member
Thread Starter
Join Date: Dec 2007
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
Question

thank you for the reply and my being so vague with the info.
so i will try again.i already have a sub panel that is wired for
a back-up generator.the sub panel has a dual supply main breaker and generator breaker with a "handle interlock" to prevent "both" being opened and close at the same time.this should prevent back feed to commericial power when the generator is in use.do you agree?the 50amp generator breaker feeds several smaller 15amp breakers.what i would like to do is not use the generator,remove the 50amp breaker and install a 30amp breaker wired to the power inverter and just use 2-15 amp breakers.this would eliminate
the need to run extension cords upstairs to apply power.
 
  #6  
Old 12-03-07, 05:18 AM
core's Avatar
Member
Join Date: Jan 2007
Location: Des Moines, IA
Posts: 1,048
Upvotes: 0
Received 0 Upvotes on 0 Posts
Ah! Much better situation than I envisioned.

So you would like to not use the generator any longer, as you put it. Could be because it broke down, you don't want to use the fuel, or just plain don't have it anymore.

Why can't you just connect the inverter where the generator used to be connected? You just want to swap out the 50A breaker for a 30A one? If everything is currently proper, sure you _could_ do this, but why? Personally I don't see the point to change anything at all! The purpose of the 50A breaker is to protect everything behind it, not in front of it. There is no need to match the breaker size with the SMALLER inverter fuse size. Imagine having to change the breaker every time you bought a different generator!

But with that said, since your original question was if there was "any safe way" to connect this, I'm guessing something else might be at play here. If you had previously had a safe way @ 50A you probably wouldn't be asking about a safe way for 30A in such a vague manner.

The subpanel doesn't know or care that it's now a 2kW "generator" instead of the ~6kW you had before. If you leave things alone you can always hook a generator back up if you ever have the desire.
 
  #7  
Old 12-03-07, 05:51 AM
J
Member
Join Date: Sep 2002
Location: welland ontario
Posts: 8,038
Received 515 Upvotes on 420 Posts
The interlock kit would be a safe way. Is the inverter 120/240 volts? If not then you have another problem. You can only feed half the circuits in the panel if it is only 120volts.
No need to change the breaker. The inverter has built in fuses so it is already protected.
 
  #8  
Old 12-04-07, 02:57 AM
D
Member
Join Date: Aug 2004
Location: USA
Posts: 524
Upvotes: 0
Received 0 Upvotes on 0 Posts
A couple of other observations,

First, what do you want the inverter to power? 2,000 watts really isn't that much. You may be able to run a small/medium TV, computer or microwave from it, but not at the same time. Like generators, most inverters have maximum and continous power ratings. Is 2,000 the maximum rating or the continous rating? Do you need to run a motor, such as a fridge, pump or A/C unit? The inverter may not be able to do this. Even some generators have trouble with motors.

Second, how long do you want this to run? With a single 12volt battery, at max load, I wouldn't expect more than an hour or so.

Hope this helped!
 
  #9  
Old 12-11-07, 04:27 AM
J
Member
Thread Starter
Join Date: Dec 2007
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
Exclamation wiring a 3-prong 120 volt inverter to 50 amp breaker?

Originally Posted by joed
The interlock kit would be a safe way. Is the inverter 120/240 volts? If not then you have another problem. You can only feed half the circuits in the panel if it is only 120volts.
No need to change the breaker. The inverter has built in fuses so it is already protected.
jesgolf,yes it is only
120 volts,so would it still be possible to,safely,wire the inverter to the breaker? would wiring the black wire,as the hot,to one side of the breaker and wiring the white as the return to the othe side and the bare wire to the grounding bar work,safely?
 
  #10  
Old 12-11-07, 04:31 AM
R
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,245
Upvotes: 0
Received 0 Upvotes on 0 Posts
Originally Posted by JESGOLF
would wiring the black wire,as the hot,to one side of the breaker and wiring the white as the return to the othe side and the bare wire to the grounding bar work,safely?
No. You wire this like any other 120 volt load, except that it will ast as an input. The black wire gets connected to one side of the breaker, whichever side you want to provide power to. The white wire gets connected to the neutral buss and the ground wire to the ground buss.
 
  #11  
Old 12-11-07, 07:31 PM
S
Member
Join Date: Nov 2007
Location: (near) Boise, ID
Posts: 415
Upvotes: 0
Received 0 Upvotes on 0 Posts
What are you powering? How many batteries do you have? 2,000 watts at 13 volts (typical battery voltage) is 154 amps! I hope you have a good connection between your inverter and battery. You can look at the capacity of the battery, expressed in amp-hours to get an idea of how long it will last. The faster you discharge the battery though, the lower the capacity. Do you have a way to keep the batteries charged so that you don't overcharge them, but they are ready when unexpectedly needed? This is an interesting plan for power backup; one that I wouldn't mind having for low power devices.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: