# Nodal Analysis Question  I however do not see any wrong with my approach. But I am not getting the correct answer. Is there anything to do with grounding? Or am I missing something else?

• How did you get an amperage for $V_B$? That's definitely wrong. I haven't looked through the rest yet to see what else is wrong. – helloworld922 Jan 25 '16 at 20:01
• @helloworld922 I didn't get you. Will you please elaborate? – curiousbrain Jan 25 '16 at 20:04
• In the very last line, you have $V_B = -49.37 A$. – helloworld922 Jan 25 '16 at 20:06
• In your first equation for node B, you have $I_3 + I_4 + I_5 = 0$ but your diagram shows $I_3$ flowing in to node B, while the other currents flow out. So that is a sign error. – The Photon Jan 25 '16 at 20:23

## 1 Answer

You need to be consistent with your signs and assumptions.

In writing the KCL equation for node A, you defined it as

\begin{gather} I_1 + I_2 + I_3 = 0 \end{gather}

where $I_1$, $I_2$, and $I_3$ are all leaving the node (consistent with the arrows in your diagram). However, then you immediately define

\begin{gather} I_3 = \frac{V_B - V_A}{2k\Omega} \end{gather}

This is the negative of the convention you just established. I would go through and double-check all of your signs and make sure they are consistent with each other. I can see similar issues in the KCL equations for the other nodes as well. You get lucky a few times by having a double negative cancel out your mistake, but this is just getting the correct answer for the wrong reasons.