switched neutrals

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brantmacga

brantmacga

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Location
Georgia
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Former Child
i got a call friday that the ice machine at our farm had quit working, and the repair guy they called out said it was hit with a lighting surge (we had bad weather the night before). its was almost $500 to fix it, so i picked up a SSA before heading home and installed it on my sub panel feeding the ice machine. something told me to check the plug afterwards, and sure enough, the hot prong had started to melt and the recep was burned. i checked voltage at the machine and it was ranging from 30v to 80v with it switched off. i replaced the end and recep and turned it back on. the repair guy had turned the machine back on that morning, and i'm afraid the low voltage fried the control box again, and i'm getting a violent shaking out of the compressor. anyhow, with the machine running now with the replaced recep, i'm getting 100v at the machine and 160v on the other leg of my service. i can imagine there was a bigger difference before. i went out to the shop tonight and none of the flourescent lights were working. i opened the switch box, and saw that it was wired with all of the neutrals switching instead of the hots (its about 30yrs old). i didn't have time to do any real investigating, so i can only guess the voltage caused by the ice machine has damaged the ballasts. i've been in several older buildings where all of the neutrals were switching instead of the hots. why did they do this?
 
The switches for your lights should be switching the hots but as far as why they did this i have no clue. It is diffenetly not safe. If a guy were to turn off the switch and think that there was no power to the fixture and go and work in the fixture he could get killed because the hot is not switched off only the neutral. i would take off the neutrals and put the hots on the switch. They probably didnt know what they were doing when they wired it or it just wasnt in the code back when they installed the lights.
 
I have seen lots of old houses with a switched neutral. Apparently polarity wasn't a concern during that time period.
 
yes i've seen it in a lot of old houses. i got hit changing a disposal once. i turned the switch off thinking it would be dead, but they were switching the neutral. i always check now. i was thinking about it earlier today. i guess it didn't matter when all they had were incandescent lamps.
 
brantmacga said:
i guess it didn't matter when all they had were incandescent lamps.
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Why? of course it mattered with incandescent lighting. You are still in danger of shock if the neutral is switched. Grab hold of the hot wire when you're grounded & thinking its dead ....
 
well certainly in terms of safety, but i was just thinking about damage to connected equipment.
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It doesn't make any difference to the equipment which conductor is switched. It is only a safety issue, not an operational issue.
Don
 
don, i understand that point. but what i'm wondering is when having switched neutrals, would a continuous high voltage surge not damage the equipment? they were receiving somewhere between 160v-175v for at least a day. no one was in the shop that day, so they weren't turned on at all. they worked the day before. i'm just going by deductive reasoning that this has damaged the ballasts. i can't think of anything else.
 
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