Wiring cabin lights in Serial

[sailingdog]

Duffer—

I was just trying to clarify that having a single set of wires going to the lights doesn't necessarily indicate whether the lights are in parallel or series... that it could be either... you actually have to look at the wiring to see whether they're hooked up in parallel, which is the correct way, or series, which is usually incorrect. Mind you, there are probably some strange little exceptions to this, but they're exactly that...strange little exceptions.

BTW, I never said it made sense to wire the boat with the lighting fixtures in series... which is a bad idea, just that the boat could be wired in either series or parallel...and only looking at the way the wiring is setup will tell you which it is. The number of wires running to the fixtures tells you nothing.

Originally Posted by duffer1960

Sailingdog,
I made the series comment again because you hade posted:

"It really depends on how the boat is wired... you can have the boat wired in series or parallel...."

and I was looking for some clarification on the series comment you made.

[duffer1960]

Now your comment makes sense. Thanks.

[xtatico1404]

Originally Posted by sailingdog

This is only true if you've wired the circuit with wire of a heavier gauge than necessary for the load and run length. Generally, I prefer to oversize the wiring on my boat by a bit...going up a size in wire gauge, since oversized wiring is generally not the problem undersized wiring is, and it reduces the voltage drop at the terminal end as a bonus.

SD, this is where real "know how" is important on electrical systems and unfortunately where people make mistakes. Please don't take that as me saying that your statement is incorrect. BTW, I totally agree with you on oversizing & the 80% factor.

People need to properly fuse and protect equipment. Saying that fusing is done accroding to wire size, is incorrect. Fusing depends on the location as well as the situation. A circuit with a single load might be fused differently than a circuit with multiple loads. Further more, circuits with electric motors on them are fused completely different. I always recommend, when installing a single load on a circuit, read the manufacturer's recommendation regarding fusing. It is much better to take the time to get really informed or pay some one to do the job, since electricity is serious business and an improper installation can lead to problems, including fire.

[svbeatrix]

Interesting thread. I believe the purpose of a breaker is to protect the wire, not the load. Individual fuses, or sub-panels, can protect the device. There are a lot of nice ATC (automotive type) fuse blocks available and they come in sizes from 1A to 30A and are available worldwide. I have very few of the old glass fuses on my boat.

[mjrogers]

Xtatico, You are correct. But saying that the breaker is sized in consideration of the load only is also an incomplete statement. If the breaker amperage exceeds the current carrying capacity of the wire the wire could overheat and burn. So, I will still modify my statement.

As we know all electrical devices run on magic smoke. If the magic smoke escapes bad things happen. Unless someone is able to adhere to the magic smoke containment codes, ABYC electrical wiring standards in this instance, magic smoke could escape and rain down bad Juju. Therefore, HIRE AN ELECTRICIAN.

[xtatico1404]

svbeatrix, yes the primary function of a fuse/breaker is to protect the wires, but it also offers some protection to the device that is connected to it. However, as you correctly stated, the main function is to protect the wire.

mjrogers, you got it. There is no single rule for fuse selection/application. That's why I said that selection depends on the wire it protects, the location on the system as well as the connected loads, hence the need to have the proper knoledge. As you said, bad Juju can happen.

[sailingdog]

No, in a house that might be the case... on a a boat, where there are often no switches for a circuit, other than the breaker, the breaker really has to be designed to protect both the wire and the load. That isn't always true, since I do have a few fused switch panels on my boat, to separate out the individual lighting fixtures from a single circuit breaker, but this is not generally the case on a boat.

Originally Posted by svbeatrix

Interesting thread. I believe the purpose of a breaker is to protect the wire, not the load. Individual fuses, or sub-panels, can protect the device. There are a lot of nice ATC (automotive type) fuse blocks available and they come in sizes from 1A to 30A and are available worldwide. I have very few of the old glass fuses on my boat.

[artbyjody]

Oversizing wire however actually generates more load resistance to begin with and should not be overly done or practiced as you decrease the overall cpacity of your storage system...which is the making the batteries work harder and deplete faster...
Oversizing you have to consider also distance and gauge ensure sure you do not see more than a 3% drop in voltage over the run... (if you can make sense of it - the charts http://www.powerstream.com/Wire_Size.htm)

A checklist however somewhat related:

http://www.islandnet.com/robb/marine.html#WiresCables (good site in general)

Not that it is an evil practice -however....really should be avoided...


VD= 2*K*I*L/ CSA

WHERE:

VD= VOLTAGE DROP
I= CURRENT
L= DISTANCE OF THE LOAD FROM THE OUTLET (IN FT)
K= 12 FOR COPPER AND 19 ALUMINUM (FOR MAXIMUM TEMP OF 75 DC)
CSA= CONDUCTOR CROSS SECTIONAL AREA IN CIRCULAR MILS.

[sailingdog]

Jody-

I'm not talking about going with 0 AWG wire for everything...just using 12 AWG instead of 14 AWG and such...

[artbyjody]

Originally Posted by sailingdog

Jody-

I'm not talking about going with 0 AWG wire for everything...just using 12 AWG instead of 14 AWG and such...

Yeah but we have to be careful around here after all, Cam supports using SPAM instead of proper materials for patching things