My wife needs reassurance

[alop37]

The advice I have always given my clients is don’t attempt to splice the shore power cable. The best of splices, subjected to repeated submersion can fail or become a source of excessive leakage current. Replace the cable.
Anthony LoPinto PE
Consulting Engineer

[Ryan]

So I'm an EE too and had my ABYC electrical certification a long time ago. A few notes:

• A good splice will be as good as and last as long as the rest of the cable.
• I'd venture that over 95% of shore power splices aren't done right and a poorly done splice is a fire hazard.
• It's easy to get a splice to work, it's hard to get it to last for decades in an abusive and corrosive environment.
• Use something like the 3M 82-F2 flexible inline splicing kit. Rated up to 1kV in extremely harsh conditions. Never had one fail, even after a decade underwater in near constant motion. Kit isn't cheap, easy, or quick so you're probably better off just replacing the 30 amp cable. Might be worth it for 50 amp.
• Shore power cables plugs are a poor design from a corrosion standpoint. Adding a 25' extension is just looking for trouble.
• Shore power cables don't usually short out. They have a high resistance spot, usually due to corrosion, which gets very hot and eventually melts something if you're lucky and starts a fire if you aren't
• Don't go undersized on power cable. Use the tables for amps and distance. A 25' extension is probably not sized to be part of a 75' 30A run.
• Don't buy just any old wire and make your own. Shore power cable need to be either tinned, or very well sealed and jacketed. It also needs to be flexible. Replacement plugs and sockets are a common failure point since they aren't as well sealed as a factory molded end.
• Comparing the voltage at the dock pedestal to the voltage at the boat with a full load is a great way to determine voltage drop. If you're pulling 20A and have a 5V drop, there's 100W of heat being generated somewhere.

I'd replace the entire cable if I were you.

[paul2884]

Originally Posted by SV__Grace

We have a 50 foot 30amp shore power cord and always need to use a 25 foot extension on the rare occasions we are at a dock.

The connection between the extension and primary cord shorted in wet weather.

Rather than shell out more than $200. for a 75 foot shore power cord I cut off the connections and spliced them together, crimping on appropriately sized butt connection lugs, staggering them and using heat shrink tubing to seal each connection as well as the whole splice for added strength.

Replacing a 50 foot shore power cord for $100. is fine, but I balk at spending $200. if I don't need to.

We're at anchor and it will be awhile until I can test it, in the meantime my wife is nervous about using it.

My plan is to plug it in and keep an eye on it with a temp gun, assuming that if the splice was a problem it would get hot.

So please check me out here. Is splicing a shore power cord a fine thing to do if done correctly?

I don't see why not, but "you don't know what you don't know" and I do value a happy wife!

Buy some new flex and don't bother trying to extend it, I'm an electrician and whilst you could splice it and heat shrink the cable, can you be absolutely sure that all the cores are exactly the same length and sharing the strain of pulling on the cable? Is it impossible that if some one pulled really hard one or more splice would let go, possibly touching each other and making the boat live?
Adessive lined heat shrink will fail when flexed for a period on something like a power lead coiled and uncoiled.
I cant imagine that cable prices are that much more where you are 100m of 2.5sqmm Tri rated pvc should be about £60, a bit more if you want tuff rubber but that's only really necessary if you want it to last forever in the sun (just replace it when it looks too faded, 100m will give you at least a couple of goes).
For something so cheap why are you considering something so potentially dangerous?

[Sail Away 3]

Originally Posted by SV__Grace

We have a 50 foot 30amp shore power cord and always need to use a 25 foot extension on the rare occasions we are at a dock.

The connection between the extension and primary cord shorted in wet weather.

Rather than shell out more than $200. for a 75 foot shore power cord I cut off the connections and spliced them together, crimping on appropriately sized butt connection lugs, staggering them and using heat shrink tubing to seal each connection as well as the whole splice for added strength.

Replacing a 50 foot shore power cord for $100. is fine, but I balk at spending $200. if I don't need to.


We're at anchor and it will be awhile until I can test it, in the meantime my wife is nervous about using it.

My plan is to plug it in and keep an eye on it with a temp gun, assuming that if the splice was a problem it would get hot.

So please check me out here. Is splicing a shore power cord a fine thing to do if done correctly?

I don't see why not, but "you don't know what you don't know" and I do value a happy wife!

_________________________________________
Be careful...
I would consult with a licensed electrician who is also familiar with the marine requirements for your needs. The wire sizes inside (gauge) the cord are sized for the amperage, voltage that the wire can safely carry. The longer the run the heavier the wire. I am unsure of the size required but err on the size of caution, and stay safe. Does that 75 foot cord contain the same size wire as your 50 footer???

[DShant]

I think these answers are all full of it. The correct answer is depending on how you did the splice and if it is water tight it could be a better connection than the plug and thus the plug would fail first. Of course you can’t pull more than the wire is rated for but you can check your gauge against the gauge of a 75 footer and I am sure you will find that they are the same. I think your idea to monitor it for a while with a heat gun is good and keep an eye on the jacket for frays abrasion etc.
I have spliced cords and made my own Y connectors all the way up to 460V on my larger boat in the past with no issues. I have never had any issues with a Marina over a power cord either that also sounds like BS in the US Canada, Central America and the islands. New Zealand as one reply points out could be different. If your wife is sweaty about it have the Marina electrician look at it.

[Slacktime]

You are only asking for trouble with the splice. It will be the weak point in the cord. E.g. Flexing, weather temperature changes tension etc. Get a proper cord.

[Dave9111]

I'm a EE as well.

Spicing a power cord and then having it lay on your boat to save money is poor decision.

How confident do you feel in your cable splicing ability? Do you splice cables frequently? If that splice starts to break down it will get hot and you may not be at the boat.

I would not want a hot cable splice sitting on my fiberglass deck!!

No good will come from that!

Look at it this way:

A New 75 ft, 30 amp cordset - about $200
Durability - about 10 years
Cost per year = $20

So skip eating out once a year. You will lose weight, have a safer boat, AND your wife will be happier. :-) All good things!

Replace that cord. Its a no-brainer. Why are we discussing this?

[JamesPNW]

Originally Posted by SV__Grace

A new 75 foot power cord is close to $200. not including shipping.



I don't want to just replace the plugs because I want to eliminate connecting 50' and 25' cords to get the length I need.



8 bucks for a 50 foot cord would not be for marine shore power.

Buying a wife happiness for $200 is a very good deal. I remember paying a lot higher price than that many times over and still do. With the 30A and 50A electrical hazards, I think you get to kill two birds with one stone by replacing the cord.

[Ken Fry]

Originally Posted by SV__Grace

1. The connection between the extension and primary cord shorted in wet weather.

2. So please check me out here. Is splicing a shore power cord a fine thing to do if done correctly?

3. ... and I do value a happy wife!

1. Shorted? Seems unlikely, as a short requires that an electrical conductor (something more conductive than salt water) bridges the two leads. More likely would be a high resistance connection causing heating, which leads to failure.

2. No, it's not a fine thing to do. But even worse is the fact that you have not done it "correctly" given that the wire gauge of a 75 foot cord should be larger than for either a 50 foot cord or a 25 foot cord.

3. Your wife is correct to worry, and she is not in need of "reassurance". She is more likely in need of an apology and some respect for her correct opinion. Get a good shore power cord that does not require use of an extension cord.

[Bill_Giles]

I can buy the cable and end fittings for about $50 in the UK for 150 feet of shore based power hookup. I assemble them myself. I am not an electrician. No checks, stamps, inspections. Nobody cares, as can be seen from some of the stuff I have observed. We are 240v which is deadlier than the 120v elsewhere. Although the electric stands delivering the power are very sensitive to any defects downstream and will trip out if the Earth protection is compromised. The stands are generally very well maintained. But I cannot understand why your cables are so expensive.

[r.stokes]

Originally Posted by SV__Grace

In my 40 years owning keel boats and keeping them in marinas, I've never had a marina inspect a shore power cord!
...

We run two marinas, one private, one public. And at both locations:

1) the owners must declare their cord safe every year as part of their moorage renewal and
2) we unplug both ends and inspect them every year (not at the same time the declaration was done).

If we find a bad cord either during inspection, or as a result of an inadvertent find/incident, we unplug it and contact the owner ASAP so they can replace it. If we find it plugged in again, we unplug it again, cut the bad end off and contact the owner again, No BS, no tolerance - argue all you want and if you don't like it, we'll be happy to refund your moorage and wave as you head out for smoother waters.

You can try and convince yourself all you want that what you've done is safe - it's not. Spend the $200, make your wife happy and keep the rest of your neighbours safe.

[john manning]

I own an electrical engineering business which works on marine systems. In New Zealand what you have done is contrary to our electrical regulations. While splicing power cables is not wrong in itself (assuming it is done correctly) modifying a power supply lead without an electrical registration breaks the rules.

I would not accept splicing a cable is safe in a marine environment. Any outdoor connection in a power lead should be made using appropriate plugs or by power connectors inside an IP68 rated junction box. No connections should ever be in a position where they could fall into water.

The cheaper alternative to ordering a new power cable would be to buy a longer lead and reuse the plugs.

[Sunstone]

So please check me out here. Is splicing a shore power cord a fine thing to do if done correctly?

I don't see why not, but "you don't know what you don't know" and I do value a happy wife!

Something happens with your Macgyvered Power Cord and you could well be in the soup. AC, water, bad combo. No room for compromise.

Just buy the proper factory made marine cord and don't mess around.

Cheers,
JB

[Nibiruwayne]

Originally Posted by SV__Grace

We have a 50 foot 30amp shore power cord and always need to use a 25 foot extension on the rare occasions we are at a dock.

The connection between the extension and primary cord shorted in wet weather.

Rather than shell out more than $200. for a 75 foot shore power cord I cut off the connections and spliced them together, crimping on appropriately sized butt connection lugs, staggering them and using heat shrink tubing to seal each connection as well as the whole splice for added strength.

Replacing a 50 foot shore power cord for $100. is fine, but I balk at spending $200. if I don't need to.

We're at anchor and it will be awhile until I can test it, in the meantime my wife is nervous about using it.

My plan is to plug it in and keep an eye on it with a temp gun, assuming that if the splice was a problem it would get hot.

So please check me out here. Is splicing a shore power cord a fine thing to do if done correctly?

I don't see why not, but "you don't know what you don't know" and I do value a happy wife!

I think you’ve heard from a lot of good folks . No need to beat you up for asking.
The connectors you used provide a mechanical attachment for each of the separated Wire ends of your cord. So moisture (with humidity)will , at some point , begin to cause corrosion which which will create a resistance point- like shutting off a water faucet at the splice. This will quietly reduce your electrical supply to the boat and decreased voltage and amperage- not good for electronics.
I would sell the 50’ cord and purchase a 75’ cord.
Better would be to keep the 50’ and have it as a spare.
Further you should avoid doing anything that could create an insurance claim for dock damage as well as for your boat.
Good luck.

[SV__Grace]

Many thanks to all that replied to my question, this old salt learned a lot.

I especially want to thank the electricians who shared their wisdom. As an amateur I appreciate your expertise and try to know and stay within my limits, which is the reason for this post.

For those who are late to the party, shortly after posting this question I received enough opinions and wisdom that convinced me to replace, rather than repair, my shore power cord.

75 foot cords are not the norm but Marinco does make one and I've ordered it. I look forward to not having to use an extension as I believe that was the cause of the short.

To those who question why I need such a long cord-

- I have a 50' LOA center cockpit ketch with the shore power connection at the helm. It doesn't matter whether I'm bow or stern to, I'm always short 10 feet or so using a 50' cord.

- I'm a full time cruiser without a permanent berth and have to accommodate all different marina configurations.

- In 2 years of full time cruising, I've only been able to skip the 25' extension on side ties when I can get close enough to the power pedestal.

I'm grateful to this forum for all the great info I've received over the years and hope I've given back at least as much as I've gotten!