220-volt junction box

[elmerinva]

All this stuff about the 220-volt in the workshop makes me ask the experts about how to connect a 220-volt junction box from the house to a boat dock. The problem is that every time we get a storm surge or a really high tide, the junction box is under water, and the connects corrode and fail. We've tried soldering the leads and sealing the box with silicon caulk, but Isabel did the bad deed and corroded it again. My electrician tells me he will try a shrink wrap, but I'm skeptical since he's the guy who installed the junction box in the first place. I thought he should have run a continuous line from the breaker to the dock--no junction box.
I've seen silicon grease connectors, but wonder how long they would hold up. I was told by the county building inspector that junction boxes in this application do not violate code--the way they have worked so far makes me wonder. Any help or advice would be appreciated.

 

[chim]

Not sure exactly what you have there. It sounds like there's a junction box with splices that gets flooded from time to time, and the water causes the splices to fail. What happens to the boat dock end?

Anyway, if it is a low-lying JB as described above, you can resplice the wires using butt crimps and heat-shrink tubing. This is if you have individual conductors running in conduit. There are kits available for direct burial cable if that's what you have. Heat-shrink or encapsulation are the two methods we use....................chim

 

[elmerinva]

Chim, the line from the house goes to a breaker box and from there, the line goes to the junction box where it is spliced with twist on connectors to a line that goes to the dock. The box gets flooded, the splice corrodes and the voltage at the dock goes dead.
My experience with heat shrink is that it would be susceptible to moisture, especially salt water. The twist on connectors with silicon grease are supposed to be waterproof, but I wonder how long they would remain so. Maybe applying dielectric grease over the heat shrink would be effective.

 

[CTyler]

What about using a silicone?

I'd solder the wires and cover with shrink wrap. Then silicone the ends of the shrink wrap. This should seal the ends and make a water tight connection.

 

[chim]

The heat-shrink we use the most of is for large cables. It has a heat activated "glue" lining them that seals them up quite well. We also use a lot of heat-shrink end caps to protect the ends of HV cable during storage and installation. HV and moisture don't play well together.

The silicone filled splices strike me as being more moisture resistant than actually waterproof.

3M makes a number of different splice kits for underground applications.

If you want a quick low tech approach, resplice with butt connectors (they are easier to seal up than wirenuts or splice caps) and wrap them tightly with self-fusing silicone tape. Stretch the tape fairly tight while wrapping it.

Hopefully you can trim enough wire back so as not to trap existing moisture between the copper and the insulation. This is more of a problem with stranded wire than it is with solid................chim (whose only salt water experience is while on vacation)

 

[slowrev]

Have the electrician solder the connections and seal up good with heat shrink and silicone.

 

[CTyler]

Everyone probably knows what I ment but just to clarify when I said "shrink wrap" I meant to say heat shrink tubing.

To much packing and moving stuff to the new house /forums/images/graemlins/confused.gif

 

[yellowdog99502]

Salt water is one of the worst conditions to work in electrically. Just the salt air is enough to corrode normal equipment is a relatively short time. Throw in the problem with electrolysis from the nearby submerged metal (boats & docks) and you have another issue to deal with.

You did not mention if the breaker at the house would trip after the junction box was submerged. Hopefully it does.

Is the breaker box (enclosure) rated for use underwater? Probably not, this is asking a lot of a breaker box. Did your local inspector know that this is a location which is subject to flooding?

The NEC requires that in wet locations enclosures shall be placed or equipped so as to prevent moisture or water from entering and accumulating within the enclosure (2002 NEC 312.2(A)). This would mean get it out of the wet area or use an enclosure built especially for this use. Please note that weatherproof and waterproof are two different animals.

The National Electrical Manufacturers Association (NEMA) and Underwriters Lab (UL) both list enclosures for use in the conditions you describe, but they are priced accordingly. These are normally galvanized and gasketed boxes specially built to prevent water infiltration. Not something you can get at Home Depot or the other home stores.

Second, what type of wire has been used? It needs to be listed as a type for wet use. That would be types MTW, RHW, RHW-2, TW, THW-2, THHW, THHW-2, THWN, THWN-2, XHHW, XHHW-2, ZW or another type specifically listed for use in wet areas. Again, this wire is more expensive and not readily available to the public.

This also means that any splices must meet the same requirements and be listed for use in wet areas. Crimp type connectors and heat shrink may or may not be the answer. Be very cautious with this and demand to see the listing of the products used.

Third, are your outlets/receptacles in the enclosure or external to it? Are they subject to the same conditions? Have they failed? Are they listed for wet locations?

I know, lots of questions here, just want to make sure you are safe.

Good luck,

Don

 

[slowrev]

Good reply Yellowdog. Do it right and it will last.

 

[elmerinva]

Yellowdog, chim, slowrev,tyler-thanks all for the input/advice. I checked the invoice the electrician gave me and he used 4 wire Aluminum line (M1d?--can't read his handwriting) down to breaker box and from there he use 10- and 12-gauge UF for the 220 and 120 lines on the dock. I've had no problem with the 120 boxes since they are a continuous line from the breaker box to the dock. The 220 line has a junction box between the breaker box and the dock and was submerged about a year ago. It corroded and tripped the breaker and we lost 220-volt power at the dock. The electrician cleaned,soldered the corroded lines and used twist connectors--no tape, heat shrink or anything. Then Isabel came and caused further submersion and failure of the 220 line. The electrician is now talking heat shrink for the next repair which according to your info will work if properly done. Since high tide and hurricanes are likely in the future, heat shrink, silicon grease, and wrap with silicon tape may at least work for a few more years. I really appreciate all the expertise and response from all of you.

Yellowdog, my understanding of the RHW, etc wire types is that they are intended for submerged applications like deep well pumps. The electrician told me that UF is adequate for applications where intermittent submersion may occur like on my dock. The problem is the connection in the junction box which gets submerged occasionally which could have been avoided had he used a single 220-line from the breaker box to the dock as he did for 120 boxes.

Isabel did submerge the 120-volt receptacles/boxes on the dock due to storm surge of 7 ft, but I cleaned them with fresh water, dried and sprayed with WD-40 (should have used CRC 5-56_but didn't have any at the time). They work fine. The 220-volt lines power a boat lift with two 1-hp motors. They were filled with salt water, seaweed, dirt and sand. Fresh water cleaning, and lots of WD-40 seemed to do the trick with them. The electronics for the boat lift and motor controllers were submerged but had not water intrusion since their waterproof enclosure really was waterproof.

In any case, the electrician hasn't done any of the followup repair since he had the flu, holidays, etc. We'll see what he does this time and I'll keep you posted if it is non-standard (non-code?) like his first work and first repair.

Slowrev, I'd love to have it done right the first time. Sometimes it's hard to find competent help. I'm still trying to find someone to deal with the trees leaned over by Isabel.