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Shore Power Pedestals: Why They Trip, Wiring Diagrams, and Troubleshooting Tips


Post by Olivia Provencher-Hennedy - Published on 9/25/19 2:07 PM

Marinas across the country are updating their onshore electrical pedestals to comply with updated code regulations. New onshore power pedestals are more sensitive to the amount of electricity leaking in an electrical circuit, causing them to trip more often than older pedestals – and boaters can expect to encounter new pedestals more frequently as more marinas update their docks to comply with new safety codes.

A boat might leave one marina where everything worked fine, but arrive at another marina and trip the breakers. Keep in mind that while tripping a pedestal can be frustrating, marinas that update, expand, or renovate their docks do not have any choice other than to upgrade to the more sensitive pedestals – and, more importantly, the new pedestals will ultimately save lives. 

Even fairly new boats have had wiring deficiencies from the factory, so your best move – rather than berating marina staff, which never works out well – is to be prepared and proactive with our latest boater guide.

Note: In this post we will not be providing guidance as to how to fix an electrical issue. This is a guide to troubleshoot. We highly advise with all things electrical that you hire someone trained and certified.

Special thanks to Robert at Shattemuc Yacht Club and Ryan at Menemsha Harbor for recommending this post topic. 

Untitled design (48)

Why Shore Power Pedestals Trip

To fix the problem, it's essential to understand why electrical pedestals trip in the first place. Due to changes in code, new onshore power pedestals are built to trip at a lower current than older models. Two main organizations updated the standard code regulations: the American Boat and Yacht Council (ABYC), which focuses on standards for recreational boats, and the National Fire and Protection Association (NFPA), which focuses more on the marina and are in charge of the National Electric Code (NEC). 

The NFPA updated codes for the electrical pedestals to trip at 30mA, lowered from the previous threshold of 100mA. When a leakage of 30mA or greater occurs, new pedestal breakers detect the imbalance within the electrical loop, and trip the pedestal, which stops the flow of current from leaking into the water.

It’s important to note that these standards set by the ABYC and NFPA are recommendations, and it is up to each state to adopt and enforce these code changes. Click here to download the NFPA updated code

 

Why Did Shore Power Standards Change? 

Shore power standards changed to reduce the risk of electrical shock occurrences on your vessel and in the water surrounding your vessel, and, as a result, to reduce drowning incidents due to electrical shock.

When electrical current leaks from the circuit, it can potentially carry into the water. When your body comes in contact with an intense electrical shock, you lose mobility within your muscles, thus the cause for drowning. The chart below outlines the effect electricity at varying strengths has on the body. 

 

mA
Effect on Human Body
0.5 - 3.0
Tingling Sensation 
3 - 10 
Muscle Contractions and Pain 
10 - 40
“Let-Go" Threshold 
30 - 75
Respiratory Paralysis 
100 - 200
Ventricular Fibrillation 
200 - 500
Heart Clamps Tight
1500+
Tissues and Organs Start to Burn
 
*Shown as 60-hz AC- effect will vary with frequency and duration on exposure

Be Wary of Fresh Water Occurrences of Electrical Currents 

No Swimming- Danger of Electrical ShockWhy should you be wary of electrical currents in fresh water? Because electricity flows through the path of least resistance. Salt conducts electricity and human bodies are naturally saltier than fresh water. The electrical current will flow through the individual because they are the path of least resistance. You may have noticed marinas posting signs similar to the one shown around the docks warning people not to swim within a certain proximity of the marina. 

 

Shore power wiring diagram

 

How Shore Power Connections Should Work

As shown in the image above, a properly functioning circuit works as such:

  1. Three different wires work together to circulate electricity:

    1. Hot

    2. Neutral 

    3. Ground

  2. Hot and neutral wires work together to create a loop of electrical current. If functioning properly, the amount of electricity coming through the hot wire is the same amount leaving the neutral wire so these wires cancel each other out. 

  3. The ground wire works as a safety net. If there is no leak in the circuit, the ground wire should hold no charge. 

  4. Neutral and ground wires connect at the electric pedestal onshore. On your vessel, however, the neutral and ground wires must be kept separate so that the ground wire doesn't have a chance of becoming active. Remember: Electrical currents return to ground by all available means. If neutral and ground wires combine, a parallel path to the ground is created. 

  • Shore power pedestals wiring diagram- minor fault
    Image 1 of 2 --> 
  • Shore power pedestals wiring diagram- ground fault
    Image 2 of 2

What Exactly is Occurs When Shore Power Trips? 

  1. If a leakage of electric current occurs – typically due to a loose connection or a damaged wire – the ground wire absorbs the electricity that leaks from the hot/neutral wired circuit, causing what is called a ground fault.

  2. The breaker in the shore power pedestal detects the leak in current and trips the system, shutting down the power source. The first image above depicts a "minor" ground fault, most likely due to an appliance problem, that is tripped at the source of the outlet.

  3. However: a fault in the grounding wire, as shown in the second image, could also cause a redirect of current from the onshore pedestal into the water and around the boat because the ground wire connects to the engine and underwater hardware.

  • Properly functioning marine electrical system
    Image 1 of 2 -->
  • Ground fault in marine electrical system
    Image 2 of 2

Protective Devices to Prevent Electrical Leaks

Although there are different types of devices you can implement to detect and/or avoid electrical issues, they ultimately work to do the same thing: detect a ground fault and break the circuit. The diagrams above illustrate a properly functioning circuit (Image 1) and a circuit that experienced a ground fault (Image 2).

Ground Fault Circuit Interrupter 

Just like the outlets in a house's kitchen or bathroom, your vessel has outlets with Ground Fault Circuit Interrupters (GFCIs) that most appliances are plugged into – and that are triggered when electricity leaks from the current (and, in the case of your boat, then flows into the water). GFCIs provide protection by tripping the outlets when an electrical imbalance is detected and stops the circuit at that specific location. Most GFCI outlets trip at 5mA.

Equipment Leakage Current Interrupter 

An Equipment Leakage Current Interrupter (ELCI), on the other hand, shuts down the boats entire power. This protective accessory trips at a threshold of 30mA, and that higher threshold is why GFCIs – with their 5mA threshold – are still used on appliances in your boat.

The ABYC rolled out this update in their recommendation in 2014, and all ABYC-compliant boats built in or after 2014 all include an ELCI. These boats' ELCIs detect leaks that otherwise wouldn't necessarily occur at a GFCI receptacle, and shut down the boat's power entirely. 

Ground Fault Equipment Protectors

Electrical pedestals use GFEPs to protect the onshore power, as opposed to protecting the vessel. This device also disconnects power at 30mA. While this precaution is a newer development and only at marinas that have adopted this practice, GFEP protects against older vessels that don't have ELCI – hence why your electrical system only trips at some marinas and not at others.

Electrical pedestals blog images (1)

 

How to Fix Bad Shore Power Connections 

Some marinas, like Fort Pierce City Marina, supply portable power testers to determine if a ground fault exists in the vessel before hooking up to power. If the marina you're docking at doesn't offer this service and you don't keep a personal handy-dandy power tester on board, click the image below to download this flow chart to help you determine where the source of a problem may exist. Dockwa_Electrical_Diagrams-V8_6There are a lot of possibilities – likely offenders include:

  • Household Appliances

  • Inverters

  • Electrical Water Heaters

  • Corroded Electrical Outlets 

  • Faulty/Chafed Power Cord

 

If you still strike out, we recommend taking a step back, cracking a cold one, and reaching out to an ABYC-certified electrician

 

Tips From Boaters

Alan H. experienced a fault on his 2006 PDQ Power Catamaran:

The Galvanic Isolator on our 2006 PDQ Power Catamaran has a feature that tests the quality of the incoming shore power and it sends information to a small on board monitor. To do so, it sends a test signal into the power feed that the new pedestals interpret as a fault. That results in a tripped breaker. The workaround is to disconnect that test feature, the monitor then shows two of the three notification lights red and one green but the Galvanic Isolator is still doing its job except for testing the incoming power. The new ones just don’t have this test feature any longer.  

 

 

Have you tripped a pedestal? Share your experiences with us and your fellow boaters in our Facebook Group. Check out our other posts about safety and boating tips, and let us know what other boating guides you'd like to see – email me at olivia@dockwa.com

 

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Post by Olivia Provencher-Hennedy

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