Adding Amps to a Boston brownstone condo

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  #1  
Old 04-26-11, 07:49 PM
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Adding Amps to a Boston brownstone condo

i live in a condo in boston that was built around 1900, renovated in 1979. my condo has 70 amps coming into it and i'm adding some appliances that suggest that more may be necessary. is there an alternative aside from running new wiring from the building main to the unit (aluminum wiring is used that is rated for the 70, not more; i'm on the top floor of 4 stories with access to the roof and attic; i've been told that running new wire is really expensive and would require entry into and perhaps holes being created in the neighbors units)?

can a step down transformer be used locally in the unit (in attic / on roof) to increase the amperage without running a new main wire? are there any concerns about that lowering the voltage?

are there other alternatives.

i'm clearly not an expert but have been doing some research online. all of the pro electricians that come in are defaulting to needing to run new wire from the basement to the unit to hold the higher current up that length, but they also give me the impression that they're not looking for alternatives and are proposing expensive solutions ($8-10k).

thanks in advance
 
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Old 04-26-11, 10:34 PM
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Welcome to the forums.

You have wiring that is rated for 70 amps. It cannot handle more without running a risk of fire. Transformers that could handle that load would cost more than the quotes you've received to replace the wiring.

$8 - $10k sounds about right to install a service upgrade in your area & building.
 
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Old 04-27-11, 05:46 AM
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The only solution is to run larger wiring from the panel to your unit.

You cannot lower the voltage because all your appliances are designed to run on 120 or 240 volts.
 
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Old 04-27-11, 06:18 AM
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There are not many alternatives to explore. In most cases. a building may only have one feeder from the utility except in special situations which have to be approved by the AHJ. Being that you are not the building owner I doubt you could approve this anyway.

What size wire is feeding your condo right now? It might be possible to replace the existing wire with copper wire as copper can handle more current. This will depend how the aluminum feeder was ran in the first place.

Why do you feel you need the increase in amps in the first place? What appliances are you adding? You should do a load calculation (Google "load calculation") and see what the required service is.
 
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Old 04-27-11, 06:48 AM
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Never used this but here is one load calculator you might try: http://www.bestinspectors.net/members/RES Service.xls
 
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Old 04-27-11, 09:00 AM
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Originally Posted by Tolyn Ironhand View Post
It might be possible to replace the existing wire with copper wire as copper can handle more current. This will depend how the aluminum feeder was ran in the first place.
That was my first thought as well. If you have a conduit directly between the building main panel and your unit it might be possible to just replace the wiring in that conduit with larger wire or with copper wire of the same size which can handle more power than aluminum. However, there are many ways the existing wiring could have been installed which would preclude this option.

To answer your main question, no there is no other alternative than to run new wires if you need more power in your unit. How you run the new wires depends a lot on the building construction and could be simple or costly.
 
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Old 04-27-11, 06:10 PM
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Why do you feel you need the increase in amps in the first place? What appliances are you adding? You should do a load calculation (Google "load calculation") and see what the required service is.
I wouldn't even think about a new feeder till I ran the loads. 70 amps is a lot more power than you may realize.
 
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Old 04-27-11, 07:10 PM
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Originally Posted by CasualJoe View Post
I wouldn't even think about a new feeder till I ran the loads. 70 amps is a lot more power than you may realize.
I agree 100%. Add that to the fact it was built in the early 1900's and I would be willing to bet it not a huge place.
 
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