Replies

1. 
   JTC1 | Oct 16, 2007 11:23pm | #1

   You will need to pull 4 new wires to the sub panel.

   Or if they are individual conductors (not sheathed into a cable), perhaps only 3 new wires - utilizing one of the "old" conductors as a ground - I think that would be legal if recoded appropriately.

   When the electrician said "pull a new wire" he did not mean to physically add a wire - he meant replace the wiring - should not be a big deal since you say it is in conduit.

   Others will chime in on sizing details will help getting a good response - copper or aluminum conductors? length of run?

   Must be a sizable electrical load in that "metal building / mother in law suite".

   Jim

   Never underestimate the value of a sharp pencil or good light.

1. 
   pinko | Oct 17, 2007 12:05am | #2

   They are individual conductors...and the electrician did actually say "pull 1 more wire" (at least this is what is reported to me).It sure sounded corky to me. And yes, there will be a sizable load in there...A new 30,000 BTU central air unit, full kitchen..elec. range..and an 19 KW on-demand water heater...not to mention power for a full work shop. In short, what I was imagining is, in fact, illegal. Correct?

1. 
   JTC1 | Oct 17, 2007 12:11am | #4

   Yes, it is illegal.

   Jim

   Never underestimate the value of a sharp pencil or good light.

2. 
   BryanSayer | Oct 17, 2007 12:08am | #3

   I'm having a hard time imagining this MIL suite not being adequately served by 100 amps. Are they sure the problem isn't one of not enough amps actually being fed into the line? That is, correct the feed to the main panel, make sure the run doesn't have a voltage drop problem from being too long.

   But maybe the MIL lives in the Taj.

1. 
   edlee | Oct 17, 2007 12:27am | #5

   I'm having a hard time imagining this MIL suite not being adequately served by 100 amps.

   If that water heater really uses 19 Kw, that's a pretty significant load, even if it's occasional. Add the electric range, maybe figure 8 Kw for load calc,  AC and workshop, lighting........100a is low.

   Ed

1. 
   pinko | Oct 17, 2007 03:50am | #6

   Thanks for the responses.Yes, Bryan, the place is, effectively, the Taj… And no, voltage drop is not a problem (40’ or so to the meter).I figured the ‘fix’ was illegal—and unsafe—just not exactly sure why.And, yes, Edlee, the w/h really does consume 19 kw (according to the manufacturer)...it pulls 80 amps… Also, add a min. of 6 kw for the A/C. Possibly more for elec. heat coils—not sure if the heat is LP or elec.I was in agreement w/ the original sparky…100A would be insufficient... The fix, I did not agree with. Thanks all for the confirmation.Btw, anyone know the specific NEC code (violation) for pulling an additional conductor to make up for low ampacity in a feed?

1. 
   BillHartmann | Oct 17, 2007 04:07am | #8

   Well the code does allow paralleling wires for larger sizes. Without looking it up I think that you need to have larger loads than you are dealing with.HOWEVER, even if you could parallel wires you need AT LEAST 2 wires, and maybe more, depending on the details of the sizes.You need one for each hot leg..
   .
   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

1. 
   McDesign | Oct 17, 2007 02:59pm | #9

   POCO parallelled cable from the pole transformer to my weatherhead; said they didn't have any 500 or 750 MCM to run to a 400-A meter base.  I know it's in free-air, but it still looks undersized.

   Small town.

   Forrest

2. 
   renosteinke | Oct 17, 2007 09:29pm | #10

   "Another wire" is known in the code as a 'parallel feed.' The code wants the wires to be as identical as possible ... same size, same length, etc.

3. 
   curley | Oct 17, 2007 04:02am | #7

   Why not run a 150 a subpannel  from the 200 a panel, but then again everybody's got to take the customer for a ride, that pick up is getting old.