Three White Wires

[minus800]

Help!
I’m replacing an AC pump on a boat refitted in UK (240v shore power)
The old wires from the discarded pump are three white wires.
The new pump wires are white, green and black. I know what they are, but how do I figure out which white wire to connect with the new ones????

[team karst]

No numbers or lettering on the wires? I must assume this is a shaded pole, brushless motor. Pick two that have continuity for power. The other should have a connection to the frame for ground. If that is not correct, I have no idea.

[jamhass]

Shut off / disconnect the AC and do a simple continuity check.

[minus800]

Here is a picture of the wires. One has a 2 on it and I think it’s the ground. One has a 1 on it and the other nothing.

[requiem]

Originally Posted by minus800

Here is a picture of the wires. One has a 2 on it and I think it’s the ground. One has a 1 on it and the other nothing.

Well, clearly you have three different colors: eggshell, bone, and ivory. While you could test them to see which is which, I'd personally use this as a reason to pull them and replace with more appropriate colors.

[team karst]

my boat has red/black for LV wiring. And all those are stamped/numbered with a circuit number. AC wiring done conventionally with Euro colors. Is a schematic of the boat available? Pretty sure all white conductors breaks some rule somewhere. THis is boat wiring, right? Not motor wires??

[senormechanico]

Could it be a three phase ac motor?

[TrentePieds]

You say the three wires FROM the discarded pump are all white. Why would that be of any consequence since you are discarding the pump?

Or did you mean that the three wires (from you 240V panel, presumably) going TO the discarded pump are all white?

If the latter is the case, disconnect shore power entirely by pulling the "umbilical". Then inspect the wiring within the panel to determine which carry power and which is the ground. Disconnect the wire from the pump switch in the panel and by means of continuity testing determine which of the feed wires at the pump site is that wire. Mark it.

In the panel find the ground stud. Continuity testing from there to the end of each of the remaining two wires at the pump site determine which is the ground. Mark it.

Now by deduction you will know that the as yet unmarked wire is the other "hot" between panel and pump. Mark it.

For marking, I like using short lengths of "shrink on" insulation in the appropriate colours to make little "bands" that identify the wires. In this county, Canada, the "hots" are white and black (or red), the "ground" is green. I believe that is also the case in the US.

So it I were in your shoes, I would insert a terminal block (if there isn't already one) at the pump site. I would mark the wires FROM the PANEL with a black band, a green band and no band. Working across the terminal block, green then connects to green, black to black and white from pump to unbanded white from the panel.

Hope that helps:-)

TrentePieds