corrosion and voltage on neutral

[tortuga]

@bitcoin miner what type of 240V system is this? 120/240 single phase, 240/120 delta, 416Y240 ?​

 

[ramsy]

42 20 amp breakers installed that go to 42 240volt outlets

I know of no 240V Line to Neutral GFCI manufactured by any major breaker manufacturer.
I do know of many GFPE or GFP breakers, but relatively few that are intended for what appear to be single pole 240V breakers in the OP.

Yes I see, 42-space load centers are common, but not 84 space, and not Quad GFCI breakers, or 240v single-pole GFCI's.

 

[ramsy]

@bitcoin miner what type of 240V system is this? 120/240 single phase, 240/120 delta, 416Y240 ?​

Most likely 240v to ground, so OP must & keep it drained & dry.

There is no NEMA class for water intrusion from conduit, so nothing listed for that.

 

[bitcoin miner]

Arrange raceways to drain, before equipment floods.

Flooded underground raceways should have a stub up into the panels.

After power shutdown, can plumber route water to outside drains by tapping those stub ups?

If equipment remains in wet location, from exterior intrusions, you need wet location listed equipment.

If still needed after drain, 240v GFCI breaker disconnects are mass produced by each manufacturer.

I could try setting the panels horizontally instead of vertically with the outlets facing up. That could be done with minimal cost using existing equipment. My quandary is that only 15 of my 90 panels are having this issue, the rest are fine. One switchgear is causing most of the problems. Removing a side panel to that switchgear shows a lot of corrosion inside it as well. I'm trying to schedule an outage to open that switchgear and check incoming conductors from the outside transformer and the bus bars from the 4000amp breaker to the 225amp breakers. Even if I figure out how to take the wires from the switchgear to the racks overhead I still am fed underground from the transformer to the switchgear.

 

[ptonsparky]

One of the things we did at a Dairy was to pressurize the room. Our issue was corrosive fumes.

 

[petersonra]

Underground conductors almost always get water in them.

The water needs a place to go if it is flowing into cabinets from below.

 

[ptonsparky]

Underground conductors almost always get water in them.

The water needs a place to go if it is flowing into cabinets from below.

Raise the cabinets above ground level or the water table.

 

[synchro]

Could there be some blockage from debris on inlet or outlet vents for the switchgear?

 

[bitcoin miner]

Could there be some blockage from debris on inlet or outlet vents for the switchgear?

No blockages, In fact the fans we are using on the SWG to pull the water out are getting corroded too.

 

[ptonsparky]

Pressurize the rooms.

 

[bitcoin miner]

Could you have some fans/ blowers that take in conditioned lower humidity air and feed it into the problem areas to reduce the amount of negative pressure pulling in humid air?

I am creating a PVC pipe path from our hot aisle to the bottom of one panel and putting a vent on the top hopefully forcing hot air into the panel and exiting out the top keeping everything dry. Can't use that solution when it starts getting hot outside though.

 

[synchro]

I am creating a PVC pipe path from our hot aisle to the bottom of one panel and putting a vent on the top hopefully forcing hot air into the panel and exiting out the top keeping everything dry. Can't use that solution when it starts getting hot outside though.

Perhaps you could have some HVAC equipment supply dehumidified and filtered air at a desired temperature over to the panel(s).

 

[bitcoin miner]

Perhaps you could have some HVAC equipment supply dehumidified and filtered air at a desired temperature over to the panel(s).

A lot of good suggestions but if I could figure out how to upload a couple pictures it would be easier to show what I'm up against.

 

[ptonsparky]

I take a picture with my phone. Open and crop it. Save. Open MH, start Post reply, and insert image. Save.

 

[Fred B]

OP in the NC area there can be quite the variation of relative humidity. I would start with multiple points of monitoring the relative humidity as well as Temp and dew point within the rooms. Your early statements indicate there is some use of atmospheric air from outside to cool equipment, that will allow a variating humidity levels to come into the area. The variety of panels not all creating a moisture issue would lead me to believe that your humidity levels are getting to the level that it is at time approaching the dew point and conditions of panels at specific locations. Large spaces will have differing temperature conditions throughout the space.
Anything in common with the panels that are having moisture issues (e.g.: all on a concrete wall, all on the north walls)? Surfaces that panel is mounted to can create a temperature differential within the panel that under certain conditions allow for moisture buildup.
Are all effected panels at same elevation (e.g.: all lower or upper sections)?
Is moisture issues worse at different times of year.
Even in my basement will have the concrete walls have different temperatures and at times will have some moisture depending on whether it is the north or south wall, and sunny day vs prolonged cloudy and relative humidity."

 

[ptonsparky]

Why only the neutral? Is it only the neutral on one panel, or multiple?
Is it overloaded?

 

[Fred B]

Is it overloaded

Would a loaded neutral vs a non-loaded make a difference? (thinking out loud) Would a warmer AL terminal with the introduction of moisture create more, or less, corrosion? How much warmer would it need to be? Warmer seems it would mean more rapid evaporation or less condensation onto a connector.

 

[ptonsparky]

Thinking out loud as well
How was the 1st failure repaired? Both conductor and termination replaced?
Using the same lug can result in a repeated failure. Been there Done that.
Not cutting back to undamaged conductor is also a failure point.

 

[bitcoin miner]

OP in the NC area there can be quite the variation of relative humidity. I would start with multiple points of monitoring the relative humidity as well as Temp and dew point within the rooms. Your early statements indicate there is some use of atmospheric air from outside to cool equipment, that will allow a variating humidity levels to come into the area. The variety of panels not all creating a moisture issue would lead me to believe that your humidity levels are getting to the level that it is at time approaching the dew point and conditions of panels at specific locations. Large spaces will have differing temperature conditions throughout the space.
Anything in common with the panels that are having moisture issues (e.g.: all on a concrete wall, all on the north walls)? Surfaces that panel is mounted to can create a temperature differential within the panel that under certain conditions allow for moisture buildup.
Are all effected panels at same elevation (e.g.: all lower or upper sections)?
Is moisture issues worse at different times of year.
Even in my basement will have the concrete walls have different temperatures and at times will have some moisture depending on whether it is the north or south wall, and sunny day vs prolonged cloudy and relative humidity."

Hopefully these pictures will tell the tale better than I can.

 

[bitcoin miner]

Hopefully these pictures will tell the tale better than I can.
View attachment 2569636 View attachment 2569638 View attachment 2569641 View attachment 2569642 View attachment 2569643