ampacity of disconnects

Richard19068

Richard19068

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Jun 11, 2004
1,643
Oday 31 Redondo Beach
Normally I would just use butt connectors but to ease installation of a new holding tank pump I want to use disconnects. Do I need to worry about the carrying capacity of the disconnects? They will be in a dry area and covered with heat shrink.

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Thanks.
 
D

dlochner

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Jan 11, 2014
11,480
Sabre 362 113 Fair Haven, NY
If the disconnects are properly sized for the wire, they will carry the current. They are not designed for frequent disconnects and the connection will get a little weaker and looser every time it is disconnected. For a pump that will only be disconnected when it fails far in the future, they should be fine. That's what I use on the pump for my refrigerator.
 
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Don S/V ILLusion

Don S/V ILLusion

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Sep 25, 2008
7,109
Alden 50 Sarasota, Florida
The weakest link here is improper crimping, not the butt connection itself. If you lack the proper size crimper, you might want to find/borrow one.
 
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D

dlochner

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Jan 11, 2014
11,480
Sabre 362 113 Fair Haven, NY
Richard19068 said:
I plan on using one continuous piece of shrink tubing to cover both ends of each connector so they will be fully encased. That should do it shouldn't it?
Click to expand
That sort of defeats the purpose of the disconnects. You will end up off the connectors because the heat shrink won’t come off. Might as well use butt connectors.
 
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Rich Stidger

Rich Stidger

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Feb 10, 2004
3,948
Hunter 40.5 Warwick, RI
dlochner said:
That sort of defeats the purpose of the disconnects. You will end up off the connectors because the heat shrink won’t come off. Might as well use butt connectors.
Click to expand
At the time the disconnect is needed, the heat shrink can simply be cut off and replaced after the connection is re-made.
 
D

dlochner

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Jan 11, 2014
11,480
Sabre 362 113 Fair Haven, NY
Rich Stidger said:
At the time the disconnect is needed, the heat shrink can simply be cut off and replaced after the connection is re-made.
Click to expand
That's not been my experience with removing good heat shrink with an adhesive. Easier to just use good quality heat shrink fittings and squeeze a little dielectric grease into the female fitting before connecting.
 
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Richard19068

Richard19068

.
Jun 11, 2004
1,643
Oday 31 Redondo Beach
dlochner said:
That sort of defeats the purpose of the disconnects. You will end up off the connectors because the heat shrink won’t come off. Might as well use butt connectors.
Click to expand
The reason for the disconnects is it's going to save some uncomfortable contortions with the crimpers in the installation. It will be easier to crimp on the disconnects, do the installation, push the connectors together and then shrink the tubing. Less time with my head upside down with my arms in an unnatural position trying to ensure a good crimp. When it comes time to disconnect I will just cut them off.
 
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J

jrussnogle

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Apr 19, 2010
59
S2 9.2C Lincoln, NE
If the area is truly dry and covered, I’d suggest a 2 pole terminal strip and ring terminals with heat shrink.
 
High Current

High Current

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Sep 11, 2022
66
Catalina 34 mk 1.5 Rockland ME
For an intermittent load like a holding tank pump they're definitely OK. For continuous loading I wouldn't go above 15A. Lots of factors to consider, like thicker wire being a better heat sink, but I've heard horror stories about these heating up and expanding, which raises resistance and makes them heat more, etc...

dlochner has excellent advice, especially on minimizing connect/disconnect cycles and using dielectric grease. I've always been skeptical that heat shrink on terminals does much of anything, but you do want to keep water out of the crimp + wire itself if you can, so getting good quality terminals that ooze a lot of glue when you shrink them seems a good bet.
 
Maine Sail

Maine Sail

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Feb 6, 1998
11,675
Canadian Sailcraft 36T Casco Bay, ME
As long a the circuit is below 20A quick-disconnect/fast-on terminals are ok. The best & most reliable we've found are made by molex. Waterproof heat shrink butt splices would be best.. Just leave the wire a bit long so you can cut them out if the pump fails...Anderson Power Poles are better from a current perspective but not very corrosion resistant. /MC4 Solar terminals are another option and water tight..Molex part numbers are in this article:

SPADE & QUICK-CONNECT TERMINALS - Marine How To
 
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Richard19068

Richard19068

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Jun 11, 2004
1,643
Oday 31 Redondo Beach
Thanks everybody for the responses. I appreciate the time and the insight.

The pump is rated at 16 amps and will only be used on a very intermittent basis so it looks like I should be fine.
 
Rick Webb

Rick Webb

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Jun 2, 2004
3,400
Hunter 23.5 Fort Walton Yacht Club, Florida
You could make the pigtail longer and the final connection somewhere for convenient.

An additional connection but all with butt connectors, preferable it seems to me.
 
Maine Sail

Maine Sail

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Feb 6, 1998
11,675
Canadian Sailcraft 36T Casco Bay, ME
High Current said:
For an intermittent load like a holding tank pump they're definitely OK. For continuous loading I wouldn't go above 15A. Lots of factors to consider, like thicker wire being a better heat sink, but I've heard horror stories about these heating up and expanding, which raises resistance and makes them heat more, etc...

dlochner has excellent advice, especially on minimizing connect/disconnect cycles and using dielectric grease. I've always been skeptical that heat shrink on terminals does much of anything, but you do want to keep water out of the crimp + wire itself if you can, so getting good quality terminals that ooze a lot of glue when you shrink them seems a good bet.
Click to expand
What a lot of folks don't realize is thatheat-shrink adhesive butt splices are used on nearly every artesian well in North America. Our well at our ski place is nearly 400' deep and bubbles out the cap every spring. The heat shrink butts have been fully submerged for more than 20+ years... The heat shrink butts are not the problem the installer is typically the issue.....
 
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High Current

High Current

.
Sep 11, 2022
66
Catalina 34 mk 1.5 Rockland ME
Maine Sail said:
What a lot of folks don't realize is thatheat-shrink adhesive butt splices are used on nearly every artesian well in North America. Our well at our ski place is nearly 400' deep and bubbles out the cap every spring. The heat shrink butts have been fully submerged for more than 20+ years... The heat shrink butts are not the problem the installer is typically the issue.....
Click to expand
Sorry for the confusion: I was referring to the "fast-on" / quick disconnect terminals. Butt splices, because they don't have an exposed end, are the only ones that will properly seal and are good for whatever current the wire gauge is, provided they're properly crimped.
 
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