What size main breaker do I need for a 125 amp sub panel?

If it’s a 125 amp panel, then you can use a 100A breaker on the main panel to feed the breaker. The new sub panel must always have the same ampacity rating as the panel that is feeding it.

What size wire do I need to feed a 125 amp sub panel?





125A is #1 copper or #1/0 aluminum (you need to call it 120A feeder, but you get to round up to 125A breaker since 120A is not made.) If you need full declared 125A you’d need 2/0 aluminum.

Can you use a 125 amp sub panel?

You can run any wire size you want. It’s OK to supply a 125A panel with less than 125A, as long as the breaker in the main panel protects the wires as follows: 14/3 copper feeder needs a 15A breaker. 12/3 copper requires a 20A breaker.

What size breaker Do I need to feed a subpanel?

Based on your question, since you will be having a subpanel, you want the breaker feeding the subpanel to be sized for the subpanel or slightly smaller. So if you purchase and install a 200A subpanel, then the breaker should be 200A. If you use a 125A subpanel, then use a 125A breaker.

Is there a 125 amp breaker?

The Square D by Schneider Electric QO 125 Amp Two-Pole Circuit Breaker is intended for overload and short-circuit protection of your electrical system and is compatible with Square D QO panels and CSED devices with 2 spaces. The ANSI-certified and UL-listed unit is rated for 120/240 VAC and 10,000 AIR.

Can you run a 100 amp sub panel off a 100 amp main panel?





Let me try and answer some of your questions. First the panels you are looking at that are rated 100A simply means you can use them for any application up to 100A. You can for example add a 60A breaker to your existing panel and protect the new subpanel with a 100A rating.

What is the ampacity of #2 Aluminum?

Allowable Ampacities of Insulated Aluminum or CopperClad Aluminum Conductors

Conductor Size (AWG/KCMIL) 60°C (140°F) TW, UF 90°C (194°F) TBS, SA, SIS, FEP, FEPB, MI, RHH, RHW-2, THHN, THHW, THW-2, THWN-2, XHH, XHHW, XHHW-2, USE-2, ZW
3 65 85
2 75 100
1 85 115
1/0 100 135

What wire do you use for 50 amps?

6

50 AMP Wire Size



For a maximum of 50 amps, you’ll need a wire gauge of 6. Fifty amp breakers are most often used to power many different appliances.

What is #2 copper wire?



#2 Insulated Wire



#2 grade insulated copper consists of unalloyed wire – thinner than 16 gauge – which includes heavy, double or plastic insulation. The grade generally covers many common types of telecommunications wiring as well as electronics such as outlet and extension cords.

How many breakers can be on a 150 amp panel?

Number of Breakers You Can Put in a 150a Panel



In most cases, a 150-amp panel has 30 spaces that can carry as many as 60 circuits, although this varies between different brands. You can fill up all the slots, installing 30 circuit breakers.

What size wire do I need to feed a 100 amp subpanel?

#4



The cable must have a wire gauge sufficient to the amperage of the subpanel—a 100-amp subpanel requires #4 copper wires or, more commonly, #2 aluminum wires, for example. (Aluminum is often used for feeder cables because the cost is typically much lower than that of copper wires.)

Does a subpanel need a main breaker?

According to most experts, the subpanel doesn’t need a main breaker as the main panel already has a feeder breaker. But, to stop power during a short circuit, it’s possible to add a main breaker in the subpanel.

How far can a subpanel be from the main panel?

The right feet would be between 4.5 to 5 feet.



The cable running from your main panel to the subpanel depends on the amperage rating. For instance, for a 30A panel, use a 10 AWG, three-wire conductor.

What is the 6 breaker rule?

The “rule of six” refers to how many breakers or throws it takes to disconnect a building from the electrical supply, so if you have more than six breakers in a box at your service entrance there needs to be a disconnect upstream of it, either in the panel or upstream.

How do I run a subpanel from the main panel?



Quote from the video:
Quote from Youtube video: You're going to be adding a subpanel always add the largest panel that that is practical to a door if you were thinking that you needed six circuits.

Does a subpanel need a neutral?

The neutral and ground MUST NOT be bonded at a sub-panel. They should only be bonded at the main service panel. If you bond them anywhere other than the main service, the neutral return current now has multiple paths, including though your ground wire.

Does a subpanel need a ground rod?

Yes, any sub panel outside of the main building requires it’s own ground rod and a ground wire back to the main building. And yes, a sub panel in the same building as the main does not need a ground rod – only the ground wire.

Can you wire a subpanel from a subpanel?

Answer: Yes. The main electrical service panel is where branch circuits originate. A branch circuit consists of the circuit conductors between the final over-current device protecting the circuit and the lights, receptacles and equipment supplied by the branch circuit.

Can you get 220 from a sub panel?



If you have a multimeter, you can also pretty easily measure voltage across two adjacent breakers in the subpanel to see if you show 220. Or measure across the incoming lines.

Can you run a 100 amp sub panel off a 200 amp main panel?

Of course you can, you can add the 100 amp breaker to your 200 amp as long as it isn’t overloaded, to start adding the subpanel you must first calculate how many yards it will be from the main panel to the subpanel, there is a formula that calculates how much friction will be on the wire at the connecting distance, …