Can You OVER Fuse Your Marine Electrical System?
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Can you over fuse an electrical system? Watch out this video to find out more. Whether you need a remote consultation design or perhaps inviting us aboard your boat, Pacific Yacht Systems is here to help. Check out the links in the description below. Hi everyone, Jeff Cote here from Pacific Yacht System with another installment of Tech Talk. We've got a fellow boater named Ian who asked, "Jeff, is there such a thing as over fusing when it comes to electrical systems?" And specifically asked between bus bars, changing wire sizes, and whatnot. With all my experience of working on boats, I would say the exact opposite is true. Over fusing? Probably I've never seen it. I guess it's possible, but no one's ever done it. Or maybe someone has and I have yet to see it. Most of us just want to assume that whatever we're doing on our boat doesn't need a fuse or there's a fuse somewhere else so we don't need a fuse. And so in the most cases, you find yourself with an electrical system not built by the manufacturer where you're actually missing fuses in a lot of different locations. I hear this all too often where boaters are saying, "Oh, to me Jeff Jeff, I've got fuses at the battery or fuses the panel. Why do I need a fuse somewhere else? Like there's lots of fuses on my boat." Well, fuses are almost like seat belts. If you've got a I don't know a bus and you've got 100 passengers, it doesn't matter that you have 90 seat belts in the bus. You need 100 seat belts for 100 passengers. If you've got like the Titanic, it doesn't matter how many lifeboats you have. The question is do you have enough lifeboats for all the passengers? So fusing is one of those things where you don't really count how many you have. Every single circuit on your boat needs to be fused for the wire connected to that appliance and also a fuse generally for that appliance. You might be able to collapse a fuse for wire and appliance together at the start of the circuit, but all too often you're going to find yourself with a specific fuse, might be a 7 amp fuse, a 6 amp fuse, 3 amp fuse uh near the appliance, and then a fuse or circuit breaker protecting the line. Whenever you change wire sizes, so let's say for example, you've got a 200 amp fuse at the battery uh connected to 2-aught wire. Then you drop down wire size and you go to, let's say for example, a gauge 8 wire. Well, when you drop from a gauge 2-aught to a gauge 8, your gauge 8 wire maximum uh ampacity of that cable is 50 amp, you're going to need to have a 50 amp fuse. So, what you want to do is you want to make sure that the wire is never the limitation. So, the fuse should always meet the requirement of the cabling and the cabling should always either meet that or exceed it. So, you can obviously uh have a fuse that would save the wire. Let's say for example, you could put, I don't know, a 30 amp fuse on a gauge 8 wire, meaning the wire will never be able to carry more than 30 amps, but you wouldn't do that because like you're losing the benefit of that 50 amp current-carrying conductor. All too often, many boaters end up not either thinking about protecting the wire on it. So, let's say for example, you might install downriggers on your boat, you might install a windlass on your boat, you might be installing solar panels on your boat, things that are added in you, but what gets overlooked is making sure that that wire is properly fused at the source. And that's key. It's not about putting a fuse anywhere in the circuit, it's putting a circuit a fuse at the beginning of the circuit. Think about our homes or commercial buildings. The AC comes into the building and right there at the beginning of all the circuits, you actually have a circuit breaker. So, every circuit starts at the panel. The circuit breaker is not in the middle of the runs, it's at the start of the runs. And you want to have that same sort of philosophy approach when doing fusing on your boat. You need to make sure that at the start of every single circuit, you need to have either a circuit breaker that is properly sized for the wire run, and or a fuse that is properly sized for the wire run. And in some instances, that fuse on a panel might be, let's say, our circuit breaker might be like 15 amps, but the fan says, "Oh, I only ever want to see 7 amps max." So, that's where just before the fan, you put in a 7-amp fuse. So, the circuit is protected for 15 amps because it's got to be at least a gauge 14 wire, and then to protect the fan, you have a 7-amp fuse just before the fan. So, over fusing, theoretically possible. In reality, I've never seen it in 20 years of my doing this business, never ever seen it. And if anything, it's actually done under fused on most boats. If you're curious and wondering what an electrical fire looks like, uh check out the video in the link below. You will be blown away. And I'm not trying to instill fear, but remember on a boat, there's not a lot of exits, and the exits generally mean that you're not landing on a dock. For many of us, you're landing in the water. So, prevention is key. If you're here in the Pacific Northwest and you're wondering if your boat is done properly, ask us to come on board and do an electrical audit. That's one of the many services that we offer. If you're remote uh somewhere around the world and you'd still like to have Pacific Yacht Systems help you, consider a remote electrical consultation and design. That's another service that we offer to boaters around the world. And thank you for watching, and enjoy some safe boating out there. Take care. Hey, fellow boaters. We're going to be doing a lot more tech talk videos. [music] If you've got any suggestions for future videos, leave them in the comments below. Once again, thank you for watching.
