Neurtal wire on SLC500.

Hi to all,

We were having a discussion about wiring up a SLC500 power supply. I am sure that we have to use a separate neutral for each power supply circuit on each rack. If someone could let me know if this is correct or is it ok to use a common neutral to hook up several PLC racks? Thank you all for your help.

Assuming that all of the chassis are connected to the same transformer, there is no difference. Assuming that all of your control power transformers' neutrals are grounded (as they should be), there is no difference, although I'd still recommend connecting the neutral from the same transformer that sources your hot wire.

As a rule, I discourage daisy-chain connections of neutrals (or hot wires) in control panels or MCCs. This connection method can create problems when performing repairs, and can lead to overloaded circuits. I prefer to see each device have it's own wire connected to a central bus.

Thank you very much for your help Bit.

The main thing is not to overload your neutral, regardless of how many devices you connect to it. A neutral is a current-carrying conductor. It must have the same ratings factors applied as your hot wire. Whether you can add loads depends on the existing load + the proposed load. If your neutral is a #14 and you have 12 Amps on it (80% of the NEC allowed load for a 75-degree C rated #14 conductor), then you should not add additional loads.