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Voltage running through metal enclosure box


CaC

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I bought a LOR professional series controller off of eBay to add on to my light show. I noticed if I rested my wrist on the metal box for a few seconds I would get a shocking sensation running through me. I inspected the box and noticed what appeared to be burn marks, so I broke out the multi meter and did some tests. I found that there is about 3v running through the box at any given time and about 19-20v running through it if I am touching it. Is this normal? my other LOR controllers are plastic so I haven't noticed or tested this on them. Not sure what I should do or if I should worry. I can post some pictures of the box in question if you'd like.

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5 minutes ago, Mr. P said:

That can be a potentially dangerous situation, you really need to check the grounding asap.

Yes, I know. I am trying to check everything as I don't want to burn my house down. I have my controller connected to an outdoor GFCI receptacle that has its ground wire connected to my breaker panel ground bus. I did try and measure the voltage across the metal heat sinks on my plastic LOR controllers and there was nothing on those, so it's definitely something with this unit.... not really sure where to go now.

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If you can feel a tingle and measure voltage on the metal box itself then your grounding is bad. You should have a clip, screw or strap connected to the box going to the green ground wire and the power cord should be three wire type. The GFCI should trip if the box is grounding out properly.

Once you have that fixed start checking for a short somewhere as the box itself should not have power going through it.

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2 minutes ago, Mr. P said:

If you can feel a tingle and measure voltage on the metal box itself then your grounding is bad. You should have a clip, screw or strap connected to the box going to the green ground wire and the power cord should be three wire type. The GFCI should trip if the box is grounding out properly.

Once you have that fixed start checking for a short somewhere as the box itself should not have power going through it.

Guess I'm going to have to take it apart. The guy I bought it from said it was a DIY kit so maybe the issue lies there. I only feel the tingle after an extended time which is why I thought it was weird. If I just touch the box, move it around, etc. then I get nothing. If I keep my hand in the same spot for a about 15 seconds, then I can feel a little. Definitely not the tingle you get from 120, but it still concerns me.

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Since it was a DIY I would check that the board is raised up from the metal box with insulated spacers, check that any cable/wire clamps are not over tightened and cutting into the cable/wire. Also ensure that there is some type of wire or strap connecting the metal box itself to the grounding system.

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21 minutes ago, Mr. P said:

Since it was a DIY I would check that the board is raised up from the metal box with insulated spacers, check that any cable/wire clamps are not over tightened and cutting into the cable/wire. Also ensure that there is some type of wire or strap connecting the metal box itself to the grounding system.

Thanks for the tip! I took the box apart and saw the main supply line for channels 9-16 had the hot wire was slit and ground wire sliced was cut completely. If it was positioned just right, it made contact with the case. I hope that was my issue. The board is raised up from the heat sink with metal spacers and the metal heat sink was directly in contact with the metal box; there were no insulators whatsoever. What should I to about this? There were yellow strips of what appeared to be burnt foam all over the case but nothing actually insulating the controller from the metal enclosure.

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2 minutes ago, CaC said:

Thanks for the tip! I took the box apart and saw the main supply line for channels 9-16 had the hot wire was slit and ground wire sliced was cut completely. If it was positioned just right, it made contact with the case. I hope that was my issue. The board is raised up from the heat sink with metal spacers and the metal heat sink was directly in contact with the metal box; there were no insulators whatsoever. What should I to about this? There were yellow strips of what appeared to be burnt foam all over the case but nothing actually insulating the controller from the metal enclosure.

Metal spacers are fine as long as they used the proper screws. However. I would still ensure that the metal enclosure has a wire/strap attached somewhere and connected to the grounding system.

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2 minutes ago, Mr. P said:

Metal spacers are fine as long as they used the proper screws. However. I would still ensure that the metal enclosure has a wire/strap attached somewhere and connected to the grounding system.

I'm going to go through and inspect everything tomorrow and run some voltage tests again. I'll make sure everything is connected properly before I use it. Thanks for your input and assistance, it's much appreciated!

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The Green wire SHOULD have been bonded to the metal CASE and all exposed metal parts (not part of the board)

Only one power cord? A second cord should have been a redundant ground.

Glad you found and FIXED a potential deadly issue. (just in case the GFIC outlet fails. Also Older houses may not have one. a 3 pack is cheap insurance (Outdoor outlets, Bath, Kitchen, Garage are targets to upgrade, even if there is no Ground wire in the box. <white is COMMON, not ground>)

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6 hours ago, TheDucks said:

The Green wire SHOULD have been bonded to the metal CASE and all exposed metal parts (not part of the board)

Only one power cord? A second cord should have been a redundant ground.

Glad you found and FIXED a potential deadly issue. (just in case the GFIC outlet fails. Also Older houses may not have one. a 3 pack is cheap insurance (Outdoor outlets, Bath, Kitchen, Garage are targets to upgrade, even if there is no Ground wire in the box. <white is COMMON, not ground>)

It didn't appear to be, but I'm going to verify everything before I put it out. I don't want anyone it anything injuring themselves.

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I ran a test from the metal box to ground and got .001 volts on my multimeter, both with me touching and not touching the box. I'd like to assume that the issue is fixed now. I'm looking to put this in a plastic weatherproof enclosure though, so there's no risk at all.

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4 hours ago, CaC said:

I ran a test from the metal box to ground and got .001 volts on my multimeter, both with me touching and not touching the box. I'd like to assume that the issue is fixed now. I'm looking to put this in a plastic weatherproof enclosure though, so there's no risk at all.

With the power OFF

use the low ohm setting and measure from the case to the U pin on the plug(s).  It should be a very small number, if not 0

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5 hours ago, CaC said:

..... I'm looking to put this in a plastic weatherproof enclosure though, so there's no risk at all.

I've been using the Cable Guard CG1500. Not expensive & cheaper the more you buy...

http://www.diyledexpress.com/index.php?main_page=index&cPath=16

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17 hours ago, TheDucks said:

With the power OFF

use the low ohm setting and measure from the case to the U pin on the plug(s).  It should be a very small number, if not 0

Yep, it's like .001

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