Any electricians in the house? Question on adding subpanel

[vi edit]

When my house was built they completely filled up (less two singles on each side of the bottom) my 200 amp panel.

I'm looking to add on a sub panel to supply an on-demand electric heater for radiant heat and panel access for limited basement finishing.

I had a handyman I know who does a lot of electrical work (although not a licensed electrician) come out and he wanted to tap into the main feed coming into the house, split it out and then feed it into a small 60 or 100 amp sub panel.

He said that since my main box was so tapped out I didn't have many other options short of a huge rewire. And since that was the way he had to do it the main power had to be cut since he would otherwise be working with a 240v hot feed that had no user operated breaker in front of it.

So my questions are...is that an acceptable(although not common by my research) way to go about adding a sub panel and would an electric company freak out about asking for a temporary disconnect to house for in-house service updates?

Load wise I'm not really worried. Most of my major appliances are gas - stove, dryer, water heater, and furnace. I just needed more space in the panel.

I'm going to make a couple calls to some more "legitimate" guys who are actually licensed but I'm scared about the prices I'm going to get back.

 

[Red Squirrel]

If the panel is fed by a fused cut off, I think it is permissible to do that. I'm just not sure how you'd go about double tapping the cut off as you can't just stick two wires under one lug.

The easiest and more acceptable way would be to tap into the existing panel. I'm not sure why he thinks it would take a rewire, just need to find a circuit that has enough slack (probably one at the bottom of the panel) pull it out, put in a new double pole breaker for the new panel, install the new panel, and install this sacrificial circuit into the new panel. If there's not enough slack to move it over to the new panel, it's acceptable to just splice another wire to it into a junction box outside of the panel, as long as that junction box is accessible.

I think you may even be able to splice it inside the existing panel and have a wire come out and go to the other panel, but I'm not positive on this, from a code aspect, as the "direction" of current is now entering the panel instead of coming out, and could potentially cause confusion. I'd just go with a ceiling mounted jbox. It's only one double pole circuit you need to sacrifice. Not a huge deal, all the other wires stay.

 

[Analog]

When my house was built they completely filled up (less two singles on each side of the bottom) my 200 amp panel.

I'm looking to add on a sub panel to supply an on-demand electric heater for radiant heat and panel access for limited basement finishing.

I had a handyman I know who does a lot of electrical work (although not a licensed electrician) come out and he wanted to tap into the main feed coming into the house, split it out and then feed it into a small 60 or 100 amp sub panel.

He said that since my main box was so tapped out I didn't have many other options short of a huge rewire. And since that was the way he had to do it the main power had to be cut since he would otherwise be working with a 240v hot feed that had no user operated breaker in front of it.

So my questions are...is that an acceptable(although not common by my research) way to go about adding a sub panel and would an electric company freak out about asking for a temporary disconnect to house for in-house service updates?

Load wise I'm not really worried. Most of my major appliances are gas - stove, dryer, water heater, and furnace. I just needed more space in the panel.

I'm going to make a couple calls to some more "legitimate" guys who are actually licensed but I'm scared about the prices I'm going to get back.

I wouldn't do it that way. I have a 225A main 42 space panel in the house. I also have a 60A feeder to a sub panel in my shed. There is a 60A 2 pole in the main panel that feeds the sub panel. Why can't you do the same? You'll have to sacrifice a couple of breakers to do that, but you could then put them in the new panel, which I presume, would be located right next to the old one.

 

[Kwatt]

NO! You must be able to kill all circuits with 1 (one) disconnecting device.


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[Red Squirrel]

NO! You must be able to kill all circuits with 1 (one) disconnecting device.


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I think you are allowed up to 6 disconnects, or is that a grandfathered rule for split bus panels?

Either way, I prefer having 1 disconnect, so I'd only do it if there is a master disconnect to tap into. Otherwise just feed off the other panel, which imo no matter what is the best way.

 

[vi edit]

I wouldn't do it that way. I have a 225A main 42 space panel in the house. I also have a 60A feeder to a sub panel in my shed. There is a 60A 2 pole in the main panel that feeds the sub panel. Why can't you do the same? You'll have to sacrifice a couple of breakers to do that, but you could then put them in the new panel, which I presume, would be located right next to the old one.

I think his biggest concern was enough power to the sub and space in the panels. The tankless heater needs two 50 amp breakers.

I'm truly ignorant of anything high voltage so I have no clue what is good/bad/right/wrong.

 

[Red Squirrel]

I'd just put a 100 or even 200 amp breaker in the main panel for the feed to the new one and you should be fine. It's ok to feed a big panel off another big panel, even if they're the same rating. The main breaker on the sub panel is more or less of a cut off as it's more likely for the upstream main to trip in the even of an overload. So you are still safe.

 

[Analog]

I think his biggest concern was enough power to the sub and space in the panels. The tankless heater needs two 50 amp breakers.

I'm truly ignorant of anything high voltage so I have no clue what is good/bad/right/wrong.

shouldn't be a problem. You can feed from your main like the way I mentioned without difficulty.

 

[DrPizza]

Another possible solution: They make half width breakers now for many brands - apparently this effectively lets you up to double the number of circuits you can have, though I'd imagine the wiring would get a bit dense inside if it's not incredibly neat and organized.

Don't forget - just like the lines in your circuits (mostly 12 gauge) are limited to 20 amps, the line from the telephone pole to your box is also rated to a certain amperage. I don't know if they put in much heavier lines than necessary, but unless they do, you would be effectively increasing the maximum possible load put on your service. THIS, I don't think, the power company is going to allow.

If you have two open slots, that's all it takes to put in a sub panel. Well, one actually, but I'd assume you want 240V in the sub panel.

 

[SNC]

If the panel is fed by a fused cut off, I think it is permissible to do that. I'm just not sure how you'd go about double tapping the cut off as you can't just stick two wires under one lug.

The easiest and more acceptable way would be to tap into the existing panel. I'm not sure why he thinks it would take a rewire, just need to find a circuit that has enough slack (probably one at the bottom of the panel) pull it out, put in a new double pole breaker for the new panel, install the new panel, and install this sacrificial circuit into the new panel. If there's not enough slack to move it over to the new panel, it's acceptable to just splice another wire to it into a junction box outside of the panel, as long as that junction box is accessible.

This. + make sure the ground is not bonded to the neutral. Always remember married in the main divorced in the sub. I recommend getting a real licensed sparky.

 

[Kwatt]

I think you are allowed up to 6 disconnects, or is that a grandfathered rule for split bus panels?

Either way, I prefer having 1 disconnect, so I'd only do it if there is a master disconnect to tap into. Otherwise just feed off the other panel, which imo no matter what is the best way.

Anything already installed with more than one does not have to be changed. Until a electrical permit is pulled and the meter is removed. In the jurisdictions I have been in the inspector will not sign off until it is brought up to current code.

There are some exceptions made for houses that have a service larger than 200 amps.
But, I don't know what they are.


Feeding off the main panel is the way I would go also. Just remember NOT to bond the ground to the neutral in the sub panel.



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[Kwatt]

If you have 1 opening on each side move one circuit breaker and circuit wire to the empty slot on another side. Then you will have 2 open slots on one side. Rearrange your breakers so that the 2 openings are side by side. Install a double pole of sufficient amp rating. Install new wire to sub panel. Miller Time...



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[vi edit]

Here's the current box:
https://public.bay.livefilestore.co...-NM9hgUVd2GsRSmhGTSbzxg/IMG_5547-1.JPG?psid=1

I think the bottom two are open (41 & 42). So move 36 over to 42, and do a double in 39 & 41? My sub panel will be going to the left side of the main. I'll see what I can do about tracking down a licensed guy for a 2nd opinion.

 

[Kwatt]

Here's the current box:
https://public.bay.livefilestore.co...-NM9hgUVd2GsRSmhGTSbzxg/IMG_5547-1.JPG?psid=1

I think the bottom two are open (41 & 42). So move 36 over to 42, and do a double in 39 & 41? My sub panel will be going to the left side of the main. I'll see what I can do about tracking down a licensed guy for a 2nd opinion.

That should work except move 39 to 42. Why move 36 (typo?).

Without looking under the cover I can't be 100%. And I have not seen a single phase Square D panel in a long,long,long,long,long time. Those appear to be Home Line breakers. I am not familiar with the insides of the Home Line.


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[vi edit]

Yeh. Typo. Meant move 39 over to make enough room for a double pole on the bottom left side.

 

[Rubycon]

Yeah that's homeline. Should re-do the whole thing with QO!

If all you need is a double pole for a sub panel just pull out a pair of single pole breakers and install a tandem and use that to supply both branches. Then you have your space for up to 100A DP breaker for your sub panel.

NEVER tap into the top (main).