On 21/12/19 22:08, dpb wrote:
On 12/20/2019 2:09 AM, Oumati Asami wrote:
The light in the laundry room stops working after worker had worked on
the ceiling in the next room.

There are two wires coming in to the light (or one in one out). Before
I flip the switch, both wires are not charged as tested by a tester.
After flipping the switch, both are charged. Yet, the light just won't
light.

I removed the light and plug it in to a socket, it works.

Question:

1) did the test (both wires not charged and then charged after
flipping the switch) I do make sense?

2) how could the work in the other room affect the light next room? I
do see that there are three wires in the switch box, none of them
neutral or ground. They are all live wires. Two on one side of the
switch, one on the other side. The two are charged, the other is only
charged after the switch is flipped.

The most likely is that which Clare noted before; the neutral in the
worked-on box wasn't reconnected.

If you can see the obvious issue there as he suggests, then you're good
to go. If not, since the issue appears to have been caused by the work;
I'd suggest get them back to fix the problem they created.

What was the purpose of their work just out of curiosity (altho that
might have some bearing that might make understanding what happened
simpler from afar).

--

Yes. Neutral needed to be reconnected.

Replacing kitchen ceiling was the work.