In line subpanel installation

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Old 01-19-14, 07:12 PM
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In line subpanel installation

Here is what I have. I have a pretty full 200amp main panel in my basement. I had a 100amp subpanel run from this panel to an outside shop/building. I do not come anywhere close to using its potential. From this shop panel, I have run a 50amp breaker circuit to another subpanel located in our kennel. This has a water heater and some lights/receptacles. It has a 115v window air conditioner.

I need a few additional circuits for outside lights and receptacles. My plan is to add a sub panel in the basement fed from the main panel. Again this has a 100amp breaker from the main to the subpanel. Then from the subpanel, I want to continue the run outside to the shop panel. Do I need to install another breaker, or can I somehow tie directly from the buss ? None of the subpanels have main breakers. The disconnect would be the 100amp breaker located in the main panel.
If I do need to install a breaker, what size? 100amp? Keep in mind the wire is already ran, for a 100amp circuit, I am just adding another subpanel.
 
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Old 01-19-14, 07:25 PM
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You will need a breaker at the start of the feeder and a!so at the end. The one at the end will serve as a disconnect.
 
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Old 01-19-14, 07:27 PM
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Before ansering your questions I see some problems that need to be discussed.
None of the subpanels have main breakers.
Subpanels not in the house with spaces for six or more circuits should have a disconnect. Usually a main breaker is used for that.
I had a 100amp subpanel run from this panel to an outside shop/building
That panel should definitly have a main breaker or disconnect. Probably the one at the kneels also. Are they connected with four wires.
Do I need to install another breaker, or can I somehow tie directly from the buss ? None of the subpanels have main breakers. The disconnect would be the 100 amp breaker located in the main panel.
No, that would be your OCPD. A disconnect, if needed, is located in or at the subpanel but since it will be in the same building no disconnect is needed. Tap rule might let you connect it without a breaker. The pros will have to comment on that. Main thing is you may need to bring the two remote subpanels up to code if the AHJ considers this a major change.
 
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Old 01-19-14, 07:45 PM
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Do I need to install another breaker, or can I somehow tie directly from the buss ?
NO!! Do not attempt to connect directly to the bus. The best way is to add another breaker, but if there are no spaces remaining, the tap rules could be used. Do you have any breaker spaces left?
 
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Old 01-20-14, 12:32 PM
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So If I have the 100amp breaker from my main panel run to my new sub panel, what size breaker do I run to the existing shop, if the wiring is currently using 100 amp to that panel?

I don't want to sound confusing. In other words I have 1 main panel and 3 subpanels. Currently 2 subpanels have 100amp and the other 50amp breakers feeding them. I am adding the panel between existing main panel and subpanel feeding outside shop/building.
 
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Old 01-20-14, 02:30 PM
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I have a pretty full 200amp main panel in my basement. I had a 100amp subpanel run from this panel to an outside shop/building. I do not come anywhere close to using its potential.

I need a few additional circuits for outside lights and receptacles. My plan is to add a sub panel in the basement fed from the main panel. Again this has a 100amp breaker from the main to the subpanel. Then from the subpanel, I want to continue the run outside to the shop panel.
If you already have a 100A feed to your shop building, you cannot add a second feed. In addition, you can only feed a panel once, so you cannot bring a second feed into the shop panel.

If you still have potential and space available in the shop panel, why are you considering adding to it? If you have plenty of potential but you're out of space there, you can change out the existing subpanel or add a second one off it.

Do I need to install another breaker, or can I somehow tie directly from the buss?
All branch circuits, including those serving subpanels, must have overcurrent protection for the conductors.

None of the subpanels have main breakers.
Any load center with more than six breaker positions must include a single disconnect to open the circuit feeding it.
 
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Old 01-20-14, 02:35 PM
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A sub panel in the same building as the service does not need a main breaker. How many buildings are you dealing with?
 
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Old 01-20-14, 03:11 PM
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So far you have avoided answering questions about if your shop and kennel subpanels are to code. Please start with that.
  • Do they have spaces for more then six circuits. If they do and no main breaker or other disconnect they are not code compliant.
  • Are they wired with four wires?
What may be your simplest solution to your main question is to install a 100 or 200 amp main lug only panel next to your existing panel using a 100 amp breaker to feed it. You then need to do a combined load calculation for shop plus kennel and move the shop feed to the new subpanel using a breaker based on your load calculation for shop plus kennel to feed it from the new house subpanel.
 
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Old 01-20-14, 04:50 PM
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This sounds way more complicated than it needs to be.
 
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Old 01-21-14, 05:08 PM
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ok, not trying to be complicated. The breaker installed my main house 200 amp panel which is currently feeding my shop is 100amp. Then I have a 50amp breaker feeding the panel to my kennel.
Now, I have no more spaces available in my house 200ammp panel, so I want to put in a sub panel close to the main panel. In order to do this, I need to disconnect my shop and feed the subpanel. This will make it 100 amp. Now the wire that was connected to the 100amp breaker now needs to run from the New subpanel. My question is, What size breaker do I install in the New subpanel to feed the shop?
 
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Old 01-21-14, 05:11 PM
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I am only dealing with 2 external buildings, but I need to install a new subpanel by my house main panel for extra spaces. I am going to feed the new panel with the existing 100 amp breaker then install a new breaker to feed the other 2 buildings. My question is what size breaker do I use with the existing wiring to the shop?
 
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Old 01-21-14, 05:18 PM
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You asked:
What size breaker do I install in the New subpanel to feed the shop?
and I previously answered.
You then need to do a combined load calculation for shop plus kennel and move the shop feed to the new subpanel using a breaker based on your load calculation for shop plus kennel to feed it from the new house subpanel.
That may be 100 amps but I don't know because you haven't told us the actual amps of the equipment likely to be used. Given as screwed up as that installation is I can't be sure if the person doing that work used the right size breaker for the wire and load. Tell us the actual load in amps or watts of the various equipment in both places and size of the wires and we can go from there.
 
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