Water Damage

[CarlAshcraft]

I recently attended a CEU seminar put on by Mike Holt. At this seminar he metioned if NM or MC cable gets wet from either flood or water damage from leaking pipes it was required to replace these wires. I know this is a good practice but I can't find it in writing anywhere.

Does anyone know where I can find this information in the code book?

Thanks for your help!

 

[cpal]

I recently attended a CEU seminar put on by Mike Holt. At this seminar he metioned if NM or MC cable gets wet from either flood or water damage from leaking pipes it was required to replace these wires. I know this is a good practice but I can't find it in writing anywhere.

Does anyone know where I can find this information in the code book?

Thanks for your help!

did he say MC? or BX?

You might contact Southwire regarding NM, I beleive that the NM is in trouble if moisture gets in. The packing is craft paper (kind sort a) and there is no way to determine if it will dry out. Same for Armored Cable Type AC. Paper between the armour and conductors. Wet is bas JuJu.

 

[zog]

I recently attended a CEU seminar put on by Mike Holt. At this seminar he metioned if NM or MC cable gets wet from either flood or water damage from leaking pipes it was required to replace these wires. I know this is a good practice but I can't find it in writing anywhere.

Does anyone know where I can find this information in the code book?

Thanks for your help!

Here are the NEMA guidelines

 

[WirenutNH]

I have thought about this before but have gone with the replace it thought: The conductors in NM are THHN/THWN rated then what is the danger ? These same conductors are commonly found in underground conduits that are filled with water and they work fine?

 

[cpal]

I have thought about this before but have gone with the replace it thought: The conductors in NM are THHN/THWN rated then what is the danger ? These same conductors are commonly found in underground conduits that are filled with water and they work fine?

where does it mention that the insulation of the individual conductors within Type NM are listed for "W" wet locations??

 

[Mgraw]

We went through this debate after Katrina. At first we were told all that was necessary was to redo the ends. But sometimes you would need to cut inches off the ends to get to wire that wasn't green with oxidation. I lost money on the first house I did after Katrina because I had to replace most of the wire anyway because it was too short. Then NEMA came out with their policy to replace all nmb. Three years after Katrina when we would remove the old wire to run new wire water would still drip out nmb.

 

[WirenutNH]

Good point! what is the type of conductors in NM?

 

[Dennis Alwon]

Good point! what is the type of conductors in NM?

All we know is the manufacturers are required to use 90C. They may be THWN but we don't have that available to us.

 

[Dennis Alwon]

This has been a tough question to answer. How wet is wet. If the wire is submerged in water then that is very different from NM cable getting wet. How many EC's vehicles do you see with NM cable sitting in the back of a pickup getting rained on all the time. I have seen houses roughed in without the roof on or siding on.

I know that these guys aren't throwing out the wire and I must say that there would be incredible failures all over town if it were a big issue. Now wire that is subjected to a Katrina flood is another story.

I have had many calls from homeowners who have had a leak in the ceiling and the water would run out the light fixture. They wanted to know if they needed to replace it. I must admit I always told them it would be fine.

 

[jmellc]

I may be wrong but I'm sure today's conductors in NM are THHN. They have the plastic overlayer like THHN don't they?

 

[480sparky]

I may be wrong but I'm sure today's conductors in NM are THHN. They have the plastic overlayer like THHN don't they?

They could be any 90?C-rated conductor. Take your pick.... that's what the manufacturers do.

 

[jmellc]

P. S.

If you must carry NM in an open truck, keep the ends taped up an inch or so. Works well. If MC gets wet, set it out in the sun for an hour or 2. It dries out well.