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Electric question….

2,922 Views | 36 Replies | Last: 1 yr ago by aggielostinETX
aggielostinETX
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10:25p, 3/5/23
AG
I need to replace an old outside panel. Its a dedicated 50amp run from my main breaker. On it is a 30 amp AC compressor, 20 amp run to an out building and a 20 amp run to low voltage lights.

I think the previous owner thought out building and and lights would never be used at the same time. I haven't opened the panel yet to confirm.
Any concerns setting it back up the same way?

I am thinking I shouldn't have 70 amps of runs on a 50 amp breaker?

First pic is old panel.

I am going to order need panel and have it installed.
Later pics are new stuff. Am I missing any thing?





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AgEngineer72
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7:24a, 3/6/23
AG
You should note that a panel is not sized by adding up the breaker ratings in the panel. You size it based on the loads and their characteristics. More information is needed before your question can be answered. Why do you think the current panel is inadequate? It looks like an old Federal Pacific panel that probably should be replaced but what prompted you to want to change it out? What is being powered in the out building? What new, future loads do you expect to add in the out building? Tell more about your "main breaker " that feeds the current panel. Is is a breaker in another panel?
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aggielostinETX
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In reply to AgEngineer72 • 7:46a, 3/6/23
AG
AgEngineer72 said:
You should note that a panel is not sized by adding up the breaker ratings in the panel. You size it based on the loads and their characteristics. More information is needed before your question can be answered. Why do you think the current panel is inadequate?

//I've lost all power at the out building. When trouble shooting/fliping breakers, I lost power at the AC unit. When I lost power at the AC unit, it was not when I flipped the AC breaker.

It looks like an old Federal Pacific panel that probably should be replaced but what prompted you to want to change it out?

//It seems to not be operating as designed. And it looks old AF.

What is being powered in the out building?

//It has a 10amp lift, more led lights and a small plug in heater.

What new, future loads do you expect to add in the out building?

//Maybe a fridge, lights, tv, fan.

Tell more about your "main breaker " that feeds the current panel. Is is a breaker in another panel?

//Correct, it's a breaker off the main panel. The main panel is not a Fed pack panel and has been completely replaced 18 months ago.

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Dr. Venkman
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In reply to aggielostinETX • 9:47a, 3/6/23
AG

Quote:
I need to replace an old outside panel. Its a dedicated 50amp run from my main breaker.
What is the cable size / type to the subpanel? It should be printed on the jacket.
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aggielostinETX
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In reply to Dr. Venkman • 9:51a, 3/6/23
AG
Haven't pulled the box yet. Its in the wall.
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aggielostinETX
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In reply to AgEngineer72 • 9:51a, 3/6/23
AG
Also is a FPE box, so it needs to go regardless.
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Dr. Venkman
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In reply to aggielostinETX • 9:58a, 3/6/23
AG
aggielostinETX said:
Haven't pulled the box yet. Its in the wall.
That will determine what size breaker this thing can be on.

Also, take a picture of the compressor nameplate. That will show the load and what size breaker it should be on.
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aggielostinETX
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In reply to Dr. Venkman • 9:59a, 3/6/23
AG
Check that already. 25.2 amps
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Dr. Venkman
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In reply to aggielostinETX • 10:00a, 3/6/23
AG
aggielostinETX said:
Check that already. 26.5 amps
What does it say for "minimum circuit ampacity" and "max breaker/fuse"?
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aggielostinETX
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In reply to Dr. Venkman • 10:33a, 3/6/23
AG
Dr. Venkman said:
aggielostinETX said:
Check that already. 26.5 amps
What does it say for "minimum circuit ampacity" and "max breaker/fuse"?


25.2 amps
And
40 amps
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aggielostinETX
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1:25p, 3/6/23
AG
Damn cover screw is rusted in place. This is getting fun.

Here's to penetrating oil and CLR.
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AgEngineer72
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3:25p, 3/7/23
AG
Where in east Texas are you?
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aggielostinETX
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In reply to AgEngineer72 • 3:55p, 3/7/23
AG
Bullard area
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aggielostinETX
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5:38p, 3/7/23
AG
Had to drill the screw out to get the panel cover off. I am good on the wire size, I just don't have much to work with for the new panel. Pretty sure right breaker is junk. That's the one to the out building. Explains no power out there.
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aggielostinETX
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9:07p, 3/7/23
AG
Getting the box prepped.
I need to do the back, bottom, and side punch outs.
My biggest concern right now is the neutral being long enough.

I assume I can splice on a single wire via a wire nut to get me there?

Installed the ground bus. In the current setup, the ground and neutrals are sharing a bus, and as I understand it, that's bad in a subpanel. The HVAC is entering from the bottom right.

In a correct set up the the HVAC and the outbuilding grounds needs to go to the bus, not the neutral?
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akaggie05
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5:43a, 3/8/23
AG
If the box didn't come with one, you'll need to buy a separate grounding bar so that you have completely separate ones for ground and neutral. You are correct that grounds and neutrals should not be tied together in a subpanel.

Edit: just saw the picture of the inside of the old panel. Looks like there's no separate neutral feeding the panel and they attached the neutral from the outgoing 120V circuit to ground. No bueno. You need a four-conductor cable feeding the new panel so that you can properly separate the neutral and ground. It would be different if this were strictly a 240V panel (then you would only need two hots and ground).
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aggielostinETX
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In reply to akaggie05 • 7:11a, 3/8/23
AG
akaggie05 said:
If the box didn't come with one, you'll need to buy a separate grounding bar so that you have completely separate ones for ground and neutral. You are correct that grounds and neutrals should not be tied together in a subpanel.

Edit: just saw the picture of the inside of the old panel. Looks like there's no separate neutral feeding the panel and they attached the neutral from the outgoing 120V circuit to ground. No bueno. You need a four-conductor cable feeding the new panel so that you can properly separate the neutral and ground. It would be different if this were strictly a 240V panel (then you would only need two hots and ground).


Bus is installed in picture above. Thanks for confirming
I'll confirm if current cable is a four conductor, 2 feeds, 1 neutral and a ground. If not, does it need to be rerun? Can I install a grounding rod?

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Dr. Venkman
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In reply to aggielostinETX • 9:09a, 3/8/23
AG
If this subpanel is in a separate building than your main panel, additional ground rods should be installed and bonded to the ground bar.

In the subpanel, the neutral bar (top of your new panel) and ground bar (bottom left of your new panel) should be completely isolated from each other. Neutrals go to neutral bar, grounds go to ground bar. Remove the screw bonding the neutral bar to the panel case if installed from the factory.

You should have four cables coming from your main panel - red, black, white, and bare or green. I can't tell if you have the bare/green, but you'll need it if you don't.

What size cables are coming from your main panel feeding this subpanel?
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aggielostinETX
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In reply to Dr. Venkman • 9:42a, 3/8/23
AG
Dr. Venkman said:
If this subpanel is in a separate building than your main panel, additional ground rods should be installed and bonded to the ground bar.

In the subpanel, the neutral bar (top of your new panel) and ground bar (bottom left of your new panel) should be completely isolated from each other. Neutrals go to neutral bar, grounds go to ground bar. Remove the screw bonding the neutral bar to the panel case if installed from the factory.

You should have four cables coming from your main panel - red, black, white, and bare or green. I can't tell if you have the bare/green, but you'll need it if you don't.

What size cables are coming from your main panel feeding this subpanel?


Its on the same building, just opposite side of the house.

They are isolated and bonding screw is not installed.

I don't see a ground coming from the main panel. Do I have any options besides running a new wire?

I don't know exact size but I think they are 6 AWG. They maybe 4 AWG.

Thank you all for the help.
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Dr. Venkman
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In reply to aggielostinETX • 10:30a, 3/8/23
AG
You do not need to drive new ground rods since it's in the same building.

For a #6 you can use a 70A breaker to feed this subpanel. For a #4 you can use a 90A breaker.

As far as the ground, you need some means to the get ground fault current back to the main panel. The most common way is a cable, but you can use metal conduit if that's what is housing the main conductors between the two panels.
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aggielostinETX
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In reply to Dr. Venkman • 10:42a, 3/8/23
AG
Its just a cable between the two boxes. It's all running off a 50amp breaker on the main panel side.

Can I drive a grounding rod vs running a wire back?
I honestly don't know what will be easier. Luckily we are in sandy soul so it's not hard to drive things.
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Dr. Venkman
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In reply to aggielostinETX • 10:56a, 3/8/23
AG
No, you may not use the earth as your equipment grounding conductor.
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BenTheGoodAg
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In reply to Dr. Venkman • 11:22a, 3/8/23
AG
Dr. Venkman said:
No, you may not use the earth as your equipment grounding conductor.


I feel like this should be on every fortune cookie any electrician and EE ever eats.
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aggielostinETX
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11:45a, 3/8/23
AG
Thanks guys. So I need to run a wire matching in size of the feeder from the subpanel back to the grounding bar on the main panel?

Correct?

Wondering if I shouldn't just run a whole new 6AWG cable.
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62strat
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In reply to BenTheGoodAg • 12:21p, 3/8/23
AG
BenTheGoodAg said:
Dr. Venkman said:
No, you may not use the earth as your equipment grounding conductor.


I feel like this should be on every fortune cookie any electrician and EE ever eats.
I feel like when someone is asking as many questions as the OP, they are in over their head and should hire an electrician!

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aggielostinETX
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In reply to 62strat • 1:48p, 3/8/23
AG
A lack of curiosity and desire to quit learning shows a lack of commitment and the acceptance that I can't make myself better.

I really have no desire to hirer an employee of some company to charge me $200/hr for 3-5 hours of work that only requires a medium level of skill for about 30 minutes.

I truly appreciate the information shared here and I'll take it all into account before I do anything.
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BenTheGoodAg
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In reply to aggielostinETX • 2:25p, 3/8/23
AG
aggielostinETX said:
A lack of curiosity and desire to quit learning shows a lack of commitment and the acceptance that I can't make myself better.

I really have no desire to hirer an employee of some company to charge me $200/hr for 3-5 hours of work that only requires a medium level of skill for about 30 minutes.

I truly appreciate the information shared here and I'll take it all into account before I do anything.


I think this board has a very strong and supportive DIY culture. I don't think anyone here doubts you can do the work or learn how to do it, but there's clearly a gap in your basic electrical code knowledge and what's needed to make this a safe and proper installation. That's not meant as a dig, but it is a point of concern. Electrical installations should scare you a little bit. And as much as people will share their knowledge and expertise on this site, we can't know all of what's required in your specific installation through a message board alone. You may save $600-1000, but if you burn your house down, your insurance won't cover anything unless you have this inspected.

ETA - having it inspected is a good way to do it yourself and make sure it's done right.
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62strat
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In reply to aggielostinETX • 2:31p, 3/8/23
AG
aggie said:


I really have no desire to hirer an employee of some company to charge me $200/hr for 3-5 hours of work that only requires a medium level of skill for about 30 minutes.
Spoken like a true non-tradesperson!

You are not paying for their time, you are paying for the knowledge.
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aggielostinETX
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In reply to BenTheGoodAg • 2:43p, 3/8/23
AG
Thanks Ben. It does give me some stuff to think about before I attempt to do all of this work.
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aggielostinETX
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In reply to 62strat • 2:45p, 3/8/23
AG
62strat said:
aggie said:


I really have no desire to hirer an employee of some company to charge me $200/hr for 3-5 hours of work that only requires a medium level of skill for about 30 minutes.
Spoken like a true non-tradesperson!

You are not paying for their time, you are paying for the knowledge.


Who installed this box originally? A tradesmen
Who installed the AC unit to it? A tradesmen
Who inspected the entire HVAC system including this box before I purchased the home? A tradesmen.

All of that experience really isn't working out for me right now.
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62strat
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In reply to aggielostinETX • 3:03p, 3/8/23
AG
aggielostinETX said:
62strat said:
aggie said:


I really have no desire to hirer an employee of some company to charge me $200/hr for 3-5 hours of work that only requires a medium level of skill for about 30 minutes.
Spoken like a true non-tradesperson!

You are not paying for their time, you are paying for the knowledge.


Who installed this box originally? A tradesmen
Who installed the AC unit to it? A tradesmen
Who inspected the entire HVAC system including this box before I purchased the home? A tradesmen.

All of that experience really isn't working out for me right now.
talk about assumptions. How do you have any idea who installed what looks to be about a 40 year old box?

And a known faulty manufacturer is of no fault of the electrician who installed it.

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Dr. Venkman
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In reply to aggielostinETX • 8:25a, 3/9/23
AG
aggielostinETX said:
Thanks guys. So I need to run a wire matching in size of the feeder from the subpanel back to the grounding bar on the main panel?
No. The equipment grounding conductor size depends on the breaker size feeding your subpanel. If you keep the 50A, you need a #10 Cu or #8 Al. If you use a 70A or 90A, you need a #8 Cu or #6 Al.

However, the code states it must be run in the same raceway/cable as the others. So I think technically you're not supposed to run this ground wire outside the sheath/conduit of the original cable. fyi
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aggielostinETX
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1:02p, 3/9/23
AG
Thanks

Appreciate all the help on this thread.
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aggielostinETX
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3:52p, 3/9/23
AG
Technician coming next week to give me a quote.
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Rexter
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10:22p, 3/10/23
Saw this today…


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