1/0 wire

[Kakalina]

Can I use a double run of 4 AWG wire instead of 1/0 wire. ie 2 wires terminated on the same terminal at each end.

[rwidman]

Originally Posted by Kakalina

Can I use a double run of 4 AWG wire instead of 1/0 wire. ie 2 wires terminated on the same terminal at each end.

You could but you shouldn't. If one conductor fails or the connection corrodes, the current will flow through the other conductor. If you have based your overcurrent protection on the total of the two conductors, the remaining conductor will be seriously overloaded.

A second reason is, you won't be able to perfectly match the two conductors so one will always carry more current than the other.

It would be an OK temporary fix but not a good permanent installation.

[paulajayne]

^^^^


What he said.


Correct tool for the job and correct wire for the loading.


A high percentage of boat fires are electrical.

[hard aground]

Also 2 4AWG is the same "size" as 2AWG

[Hartleyg]

4 runs of 4awg = 1 run of 1/0 Take care to make the 4awg wires equal length.

Putting all four wires into a connector and crimping them would be better for equalization than separate lugs, BUT -- you need to have the correct size connector and a proper crimp tool (which, for these sizes, will look a lot like a 24 or 36 inch bolt cutter) - those "hammer crimp" atrocities are not good.

[pcmm]

Originally Posted by rwidman

You could but you shouldn't. If one conductor fails or the connection corrodes, the current will flow through the other conductor. If you have based your overcurrent protection on the total of the two conductors, the remaining conductor will be seriously overloaded.

A second reason is, you won't be able to perfectly match the two conductors so one will always carry more current than the other.

It would be an OK temporary fix but not a good permanent installation.

This is done all the time. I just finished doing a tour of a large data center (their generators are powered by V 16 diesels! ) and all 8 of their starter circuits are wired this way, but with 4/0 AWG cables. the stuff is just massive ( yeah I'm a nerd and notice that kind of stuff!!)

[smac999]

you mean I shouldn't double up wires. but I only had 14/3 when I did my 30a shore power cord!! (no not mine... pic taken on a boat last week.....)

[Wotname]

Originally Posted by pcmm

This is done all the time. I just finished doing a tour of a large data center (their generators are powered by V 16 diesels! ) and all 8 of their starter circuits are wired this way, but with 4/0 AWG cables. the stuff is just massive ( yeah I'm a nerd and notice that kind of stuff!!)

Just because "it is done all the time" doesn't make it correct. And I am sure you know it is not done all the time, just some of the time and in some circumstances.
Rwidman (and others) are correct - it is not best practice by a long shot.

However it all about risk management, it some circumstances (like maybe the data centre you witnessed), it is acceptable as the likelihood of failure is low. Their starter circuits might only be used occasionally and well maintained and inspected regularly. In other circuits the potential for problems maybe much higher.

For the OP, consider the situation and carry out a risk analysis - even if only an informal one. Best practice is don't do it but it may be appropriate in your instance.

[pcmm]

Originally Posted by Wotname

Just because "it is done all the time" doesn't make it correct. And I am sure you know it is not done all the time, just some of the time and in some circumstances.
Rwidman (and others) are correct - it is not best practice by a long shot.

However it all about risk management, it some circumstances (like maybe the data centre you witnessed), it is acceptable as the likelihood of failure is low. Their starter circuits might only be used occasionally and well maintained and inspected regularly. In other circuits the potential for problems maybe much higher.

For the OP, consider the situation and carry out a risk analysis - even if only an informal one. Best practice is don't do it but it may be appropriate in your instance.

You may be correct, but if its acceptable in a world-class data center then I suspect its acceptable practice in some applications. The key is that the combined capacity gets you to the amperage that you need. paralleling current paths is not unusual happens inside electronics too.

[DotDun]

Originally Posted by rwidman

You could but you shouldn't. If one conductor fails or the connection corrodes, the current will flow through the other conductor. If you have based your overcurrent protection on the total of the two conductors, the remaining conductor will be seriously overloaded.

A second reason is, you won't be able to perfectly match the two conductors so one will always carry more current than the other.

It would be an OK temporary fix but not a good permanent installation.

This is a recommended method by manufacturers.....

A snippet from the Victron Multiplus manual:

[a64pilot]

An argument could be made that a wire is just noting more than many wires.
However, I think it bad practice,unless cable size makes it impossible like the huge starters and the Victron chart. I would not do it to save some money and if I saw that while looking for a boat, it may make me less interested in purchasing.

[Saltyhog]

Originally Posted by smac999

you mean I shouldn't double up wires. but I only had 14/3 when I did my 30a shore power cord!! (no not mine... pic taken on a boat last week.....)

That pic is all the more scary when you notice that the cable is solid conductor romex. House wiring. The worst part is that the folks that do this sort of thing will argue with you about how they've always done it this way and that it's been "FINE". I usually just nod and make a mental note where their slip is so I can avoid proximity.

[rwidman]

There is a big difference between doing something the correct (and safe) way and getting away with doing it the wrong way.

Knowing the right way to do something, why would someone choose to do it the wrong way?

As I posted, in an emergency, that will work but make a proper repair as soon as possible.

[DotDun]

Originally Posted by Kakalina

Can I use a double run of 4 AWG wire instead of 1/0 wire. ie 2 wires terminated on the same terminal at each end.

The REAL answer is YES! It's done generally to increase current carrying capacity of a circuit.

Without more information, one has to assume that 1/0 is what the application requires (~285a). (2) 4awg in parallel will yield ~320a. With that said, most would opt for the 1/0 cable due to ease of installation/management.

But contrary to what's been stated, there is nothing unsafe, temporary, or wrong about paralleling cables to gain ampacity.

[smac999]

Originally Posted by DotDun

But contrary to what's been stated, there is nothing unsafe, temporary, or wrong about paralleling cables to gain ampacity.

as already mentioned there are reasons not too. if one cable breaks, or say is left disconnected by mistake. you'll now have 300a going through a single 4awg. and nobody would ever know or relize untill it burns. where as if the 1/0 comes off it won't work and you'd notice right away.