# Order of resistors in parallel

Discussion in 'Homework Help' started by nzidesigner, Mar 4, 2015.

1. ### nzidesigner Thread Starter New Member

Mar 4, 2015
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Hi Does the order in which resistors are added to a parallel circuit matter? Thanks.

2. ### #12 Expert

Nov 30, 2010
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Only in the most microscopic sense. The resistance of the wire connecting the resistors exists, but I don't think you are going to meet that in the first semester. You have to be doing tens of amps before the wire resistance matters.

3. ### nzidesigner Thread Starter New Member

Mar 4, 2015
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Thanks for the reply. What I mean is the order in which resistors are added. So, eg. If I have a stove, a fryer and a toaster all in one parallel circuit. Will changing the order I turn them on make any difference?

4. ### #12 Expert

Nov 30, 2010
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No.
Difference in time does not matter to resistors, and all those loads are a form of resistor.

Mar 4, 2015
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6. ### WBahn Moderator

Mar 31, 2012
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If we model the devices as simple resistors and we ignore the current limitations of our supply, the order doesn't matter. This is very possibly the situation for your scenario.

But in practice it might matter if either the circuit can't supply all three at the same time or if there is significant inrush current (a high initial current due to the units being cold) in them.

Let's say you have a 20A circuit and the stove took 15A and the fryer took 10A and the toaster took 4A. If you turn on the fryer and stove (in either order) the circuit breaker will pop but if you turn on the stove and the toaster everything will be fine until you turn on the stove.

If there is significant inrush current in one (or more) of the devices, then even if the circuit can power all of the devices once they are on, if that device is turned on last the inrush current might be enough to trip the breaker. But if that device is turned on earlier and devices with little or no inrush current are turned on last, then you can get them all turned on successfully.

7. ### nzidesigner Thread Starter New Member

Mar 4, 2015
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Aha. Thanks so much. That makes perfect sense.

8. ### #12 Expert

Nov 30, 2010
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If that makes perfect sense, why didn't you say you wanted to know the effect on a circuit breaker? Posting this in the Homework section suggests it is typical school work for beginners. That will get you a typical school work answer.

9. ### nzidesigner Thread Starter New Member

Mar 4, 2015
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I guess l don't know what I don't know! It's posted here because it's yr 10 homework