30A wiring advice (2025 Update)

Hmm, BS 7671 allows a single overcurrent protective device to be used with parallel conductors provided that:

- the sizing and layout is such as to ensure equal current sharing, and

- there are no branches taken off one of the cables (ring final circuits are exempted from this), and

- a fault anywhere on one of the circuit cables will operate the device without exceeding the relevant conductor temperature limit (adiabatic compliance).

Multiple devices are only required if the above can't be complied with. See regulations 473-01-06 thro' 473-01-08, 473-02-05 and

But as you say, the design calculations required are well beyond the capability of the average electrician, so it doesn't happen very often.

Actually, there are exceptions for flexibility and elevators and the like, but in most circumstances....

Multiple conductors are allowed to allow extremely large installations to be fed through normal conduits in workable sizes. Special rules apply. For household size jobs, the economies of scale say 'spend the money'.

Soldering won't help a wire failing in the middle.

"PJx" arrogantly wrote >

even in alt.home.repair we try to give the best advise we know. You obviously don't give a rats ass about anyone's safety.

Get Lost Bozo while "we" get a Life and save a few lives from you!

FYI it was posted on the engineering group and others that is why you see an engineers reply!

This is Turtle

Save your bandwide. Your speaking to a Troll with no understanding of what you say.

TURTLE

This is Turtle.

Earth to PJ.

It is not allowed to troll below 200 feet of the air space for you will get into trouble with high electric wires. You know the Lesstricity stuff.

TURTLE

Geez. I thought you, of all people, would understand a guy who lives in a trailer down by the river running a couple of 14 ga wires in parallel, for the sad and simple reason that he already owns the 14 ga and doesn't have the cash for the 12 ga wire.

PJ

This is Turtle.

I understand it and that is why i will not do it. I know how to save money in many different way but that way is not one to fool with. I have done it in conduit , closed circuit boxes, and under ground circuits to pumps in the past and you can see where i do it and why. You could maybe get away with it in these types of applications because it will not start a fire. If it is run under a trailor house, through a attic, or in any area that can catch on fire DO NOT DO IT. I know all the poor boy rules on circuits that NEC does not like but this will break the NEC code and the Poor Boy Rules too.

Dirty don't burn, inside conduit don't burn, and air don't burn if put out in the open air. Now never get under trailors, in walls, in or about sheads, in attics, or in any area that can set a fire if things go wild.

Now let me go back to the NEC side of the problem. DON'T DO IT.

TURTLE

1. We often choose from more than just 2 for President.
2. They always pick from more than 50 candidates for Miss America.

The entire tag line is incorrect! lol

Wishing you and yours a happy holiday season...

Trent

Proud member of the Roy Rogers fan club!

Generally cable is rated by the size of the conductor which then translates into how much current each conductor in the cable can safely handle. If a particular gauge is suited for 20A max, then a cable containing two of those conductors can handle 20A on each of them or a cable containing three can handle 20A on each, etc. of those conductors ca