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I have a Wilo Star S 21 FX pump (water circulation) on an outside wood burner that needs to be installed. The wire that fed the original pump (an off brand) has a black and a white wire. The 2 wire power is coming from a junction box that has power going out to the door blower motor and the thermostat. All the wires coming OUT from this junction box are the same and are marked 2C 14AWG 300V. Opening the junction box, I can see that the box is grounded (the junction box is metal btw and mounted directly to the back metal face of the wood burner inside an enclosure.)

The Wilo I want to install has a slot for "N", "L" and I believe a third for ground.

  1. I have a black wire (hot) that goes to the "L" slot, and the white wire (neutral) goes in the "N" slot correct?

  2. What do I do about the ground if the wire that comes in is only 2 wire, white and black?

  3. Is it safe ignore a ground on this last 2 foot piece of wire going to the pump?

  4. Should I swap out the last run of 2 wire for a 3 wire and ground it to the junction box as well?

I really appreciate any advice here, and I apologize if this seems like a 'duh' question.

Here's the installation manual. Junction Box, Open enter image description here

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    I'm not sure what a Wilo Star S 21 FX pump is, but what are the electrical requirements for it? If you would edit your question to include a picture of the name plate on this device and/or a link to the instruction manual, it will make it much easier for someone to answer your question.
    – FreeMan
    Commented Sep 27, 2022 at 17:09
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    That is some very shoddy wiring, using cordage as cable and ignoring grounds. The grounding wire that is present should be attached to the box grounding screw location (bring a 10-32 screw if needed, the box should already have a threaded hole for it), not vaguely looped around a mounting screw (so it's not connected when the cover is off.) All the black cordage is improper and should be replaced - leaving you one white hunk of 14/2 with ground NM/B that doesn't need to be replaced, out of all the stuff in this box. Super shoddy.
    – Ecnerwal
    Commented Sep 27, 2022 at 21:51
  • All of the black cables coming in to the box that aren't white come from feeds that are for two separate pumps (only using one at the moment), and cable coming in from the thermostat/door blower/light.You can see below the box the yellow ring where all those additional cables come out of the boiler and in to the junction box. It appears the boiler came with these cables as is and everything was connected during instillation like that. The white cable is the power from the house. I agree the ground did seem haphazard. Commented Sep 27, 2022 at 23:29

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First off, some pictures of your junction box would help us determine what you can do here.

I'll address your questions one by one.

  1. I have a black wire (hot) that goes to the "L" slot, and the white wire (neutral) goes in the "N" slot correct?

Correct.

  1. What do I do about the ground if the wire that comes in is only 2 wire, white and black?

You will need to provide a ground wire. Quote from the installation manual:

The pump must be connected to the power supply by a solid cable equipped with a grounded plug-connection or a main power switch.

This means you will need to replace the cable with one that provides a grounding conductor. You are permitted either to use a cord-and-plug connection to a grounded outlet, or a hard-wire cable to a switched disconnect. The pictures of your junction box will help us determine which one would be best.

  1. Is it safe ignore a ground on this last 2 foot piece of wire going to the pump?

Nope. Not safe or legal.

  1. Should I swap out the last run of 2 wire for a 3 wire and ground it to the junction box as well?

Yes. As stated in the answer for question 2, you'll need to replace that cable with either a 2C+ground cord and plug to a grounded outlet, or a 2C+ground cable back to your junction box with a switched disconnect.

If we had a pic of the junction box we could go into better detail as to what steps to take.

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