Calling all electricians. Got a ? concerning a 70 amp breaker being replaced with a 60 amp (SIEMENS.

[MentalIlness]

Ok, The breaker box in the house is Siemens, and our electric furnace...runs off of a 70 amp breaker.

This is the breaker currently in the box.

I hear some popping....then I seen it arc. So immediately shut it off. So...im heading out to grab one, but Ive been told, that the 70amp has been replaced with a 60 amp. Now the only thing this breaker runs...is our furnace.

But my question is...can I replace it with this one ?

I am by no means an electrician, but I do know enough to change it out.

Ill be heading out soon to get it, so....thoughts ?

Thanks for any and all input.

Moved from OT
admin allisolm

 

[who?]

Get the furnace checked for problems that may be causing the breaker to have problems. Also you need to find info about your furnace to look up it's current draw.

 

[MentalIlness]

Where would I find this info at ?

 

[who?]

There may be some kind of id plate on the furnace with a model number that you can look up on the internet but what you should do is call a heating systems professional to check it out.

 

[Mayne]

you might have a short in the kilowatt heater. I'm no electrician but i am a gas fitter.

 

[RLGL]

If the furnace is rated for a 70 Amp breaker, replacing with a 60 is a no no. The more a breaker is tripped the weaker it gets. I would be more concerned with the furnace than the breaker

 

[MentalIlness]

The furnace is new. Which I know doesnt really mean it still cant be the problem. But anyway.....it is this one.
It is in a modular home.

Central Electric
Coleman EB12B
Serial 020108390
39,000 BTUH

http://www.ebay.com/itm/Coleman-Mob...12B-EB12D-EB12F-12KW-12-KW-240v-/371150726350

The breaker in the front of the furnace, is a 60 amp, and a 70 in the box.

 

[Mayne]

The furnace is new. Which I know doesnt really mean it still cant be the problem. But anyway.....it is this one.
It is in a modular home.

Central Electric
Coleman EB12B
Serial 020108390
39,000 BTUH

http://www.ebay.com/itm/Coleman-Mob...12B-EB12D-EB12F-12KW-12-KW-240v-/371150726350

I would definitely phone the company that installed it. if that doesn't help..phone the actual furnace manufacturer.

 

[Paperdoc]

You don't say where the snapping and arcing you observed happened. Inside the furnace? In your breaker panel? Inside the 70 amp breaker? Whatever, you really should be trying to figure out where that was happening and why, so it can be fixed.

If the problem was not actually in the 70 amp breaker, it may have nothing wrong with it. Then it would not need replacing.

The specs for your furnace say its load is 50.7 amps, and the MAXIMUM breaker size to protect it is 70 amp. In other words the interior components are designed to handle a max 70 amp load. But the normal actual load is just over 50 amps. That means the, IF you were to use a 60 amp breaker, the load would be running at 85% of breaker capacity. That is normally considered an acceptable safety margin. So the 60 amp breaker should be OK. Certainly NOT over 70 amps.

But I agree with others - FIRST find and fix the original cause. THEN determine whether the 70 amp breaker needs replacement or not.

 

[bruceb]

If the breaker in the furnace is a 60Amp then that is what you should also use at the breaker panel. And you should call whoever installed and wired your furnace. They may have a loose connection or a defect in the furnace. Also did they run Copper or Aluminum wires from the breaker to the furnace ? Aluminum wires require a breaker designated for use with aluminum wires.

 

[Rubycon]

12kW is 48A nominal. Typically loads are sized at 80% of the overcurrent protection. A 60A CB will work and won't trip but it may not pass inspection especially if the device nameplate has a minimum overcurrent protection value >60A.

Arcing indicates a serious fault. Especially if it has the sound of a firecracker report and instantly trips breakers and/or blows fuses!
Check all terminal blocks, wiring at contactors and the heating element itself. Instant strip heater failures at startup can be caused by an extensively long screw that reaches the nichrome wire. If it happens more in the middle it won't trip the breaker but will cause the nichrome wire to become severely overheat and fail OR could cause the high limit switch to open if close enough. The failure mode is similar to a blower motor failure or blocked airflow, etc.

 

[MentalIlness]

The "arcing" I saw, looked like it was coming from the inside of the 70 amp breaker. The switch to turn the breaker on.....the arc was seen behind it.

When it arced.....it does "not" trip immediately. The breaker gets really hot......then trips. .....but anyway, when it arced...it sounded more like a SIZZLE. Kind of like someone being tased.

There is someone coming to check it out, unfortunately, he hasnt made it here yet.

And thanks for the replies guys, it has been really informative.

 

[MentalIlness]

And you should call whoever installed and wired your furnace.

There were two previous owners of the home. So finding this out may be difficult. I believe was installed when it was built.

 

[bruceb]

Have the electrician check for any loose wires on screw terminals or even or a neutral connection. I have seen oxidized neutral wires in older homes and also a loose neutral in a switch box on a much newer home (had like 5 wires, but the wire nut should have been larger to properly tighten them) cause all sorts of issues.

 

[Micrornd]

Replace the breaker, it's faulty -

http://www.homedepot.com/p/Siemens-70-Amp-Double-Pole-Type-QP-Circuit-Breaker-Q270/100144517

https://www.lowes.com/pd/Siemens-QP-70-Amp-2-Pole-Circuit-Breaker/3129173

Just my 2¢, but you may also want to replace whoever told you that the 70A breakers were replaced with a 60A breaker.

 

[PowerEngineer]

Paperdoc is correct about your new furnace's nominal load current (50.7 amps) and the maximum recommended circuit breaker size (70 amps). FWIW, the installation manual is here:

http://www.graycoolingman.com/uploads/1/0/6/6/10667336/eb-electric-furnace-install-instructions.pdf
http://www.graycoolingman.com/uploads/1/0/6/6/10667336/eb-electric-furnace-install-instructions.pdf
As Rubycon observes, a 60 amp breaker would leave you with a reasonable amount of headroom (over nominal load current) for transient current spikes (which would normally occur when starting up). Replacing a 70 amp breaker with a 60 amp breaker is okay, and (if it doesn't trip on those pesky current spikes) it does provide you with a tad better protection (tripping at lower currents than the 70 amp breaker would). However as RLGL notes, tripping ages a breaker pretty quickly so I'd move up to 70 amps if you did see occasional trips for no reason.

Most importantly, however, I would strongly suggest that you have an electrician check out your circuit breaker box. Any arcing inside the box is a very serious concern. While the 70 amp breaker could well be the source of the arc, it is also possible that there was some other cause. There might also have been some less obvious damage done to other circuit breakers.

I hope that whatever you do (or have done) works out.

 

[crashtech]

A 50 amp load is among the heaviest of any residential circuit, and its troubleshooting is not something to be taken lightly at all. Going downward in capacity on the breaker might be a good thing, though it will subsequently be even more sensitive to any excess current draw conditions. Please make sure all your smoke alarms are functional, these sorts of malfunctions tend to burn houses down on occasion.

 

[Scarpozzi]

Aluminum wires require a breaker designated for use with aluminum wires.

Bah...Not true. Aluminum wires will work with any breaker. You should paint them with antioxidant paste to keep the wire from oxidizing. I've got 2 feeds, one indoors and one outdoors at 2 of my properties that I ran with Aluminum. Both are using standard breakers, are up to 2006 ICC (current codes here)

For your breaker issue, with the arcing, it sounds like the breaker just isn't seated properly and that there was an open (not a short). If the connection being made from the breaker to the back of the panel, it would arc between the breaker and the back of the panel. Pull the breaker out, inspect it for any burn marks from the said arcing...if it doesn't look like any metal is missing or burned too badly, pop that sucker back in there and push down on it to make sure it's making full contact. I have a 100amp Siemens breaker box in my garage (being fed from said aluminum as a sub panel). They do have a little play in them...see if it just wasn't locked down. If you actually replace it, you're probably good with a 60amp. Most of the add amperage breakers like 50 and 70amps are out there for hot tubs and things that are manufactured by small companies that throw products together and don't engineer them to be *standard. That's typically where I've seen a 70amp requirement. My whole-house heatpump is only on a 30amp breaker as it's backed up with gas.

 

[stormkroe]

Info that I found on that model says it's actually 11.4kw, which is 47.5 amps @240v, 80% breaker load would be 59.375 amps. This explains the 60 amp integral breaker.
Go for the 60 amp seimens.

 

[natto fire]

I would go with Stormkroe's suggestion of the 60A. I have been doing lots of multi-family residential units lately, and all of the air handlers ship with 60A Square D integral breakers, for field installation of resistive heat kits from 5 to 15 kW. I have also been dealing with 20 kW units, that have two of those 60A breakers, with #6 run to one and #10 run to the other.

The shop I work for mostly does Siemens, and while they are better than GE, in my opinion, they are not perfect. I am at a 60 unit place now, and have swapped out 5 bad breakers in the 800 or so that have been installed. Some are stab in some are bolt-on, but the point is that the breakers being "cheap" comes at a cost. I go through this with GFCI receptacles too. Put a couple hundred at a job, and there are bound to be DOA ones.

If you are comfortable working in a panel, I would just swap your feed breaker out with the 60A and hope that fixes it. Probably prudent to make sure the wires are tight in the unit too, especially if some tin knocker wired it up.

FYI: if it is a Square D integral breaker at the unit, the wires go behind the terminals that the set screw bites down on. It is printed on the breaker. I have never met an HVAC tech that does it right, so we usually do it.

They also never move the tap from their control transformer from 240v to 208v. I am too nice and swap the fuse and move the tap when "there is no power at the unit"