I'd say anywhere between 4000 to 5500 will be neutral enough to offer a balanced color spectrum for differentiating wire colors. Just as important as CRI is the inherent white-point of the emitters. A lot of LEDs will have a green bias, so at CCTs closer to 4000k, everything can look kinda yellowish, so you'll get less than ideal separation between brown and red, and at higher CCTs, the green cast and lack of deep red (R9) rendering can wash out reds to make them look more brown. A Lee Zircon minus green filter can help correct the white point of the LED emitter, so you have the best of all worlds: neutral color spectrum output, neutral white point, and high CRI.
I say all this as hyperbole though, you don't need a perfect light to see wire colors accurately, but they can help make for a more natural and pleasing experience.