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Transfer switch question.

7K views 25 replies 10 participants last post by  gregzoll 
#1 · (Edited)
Hi all,

I'm going to purchase a 10 circuit manual transfer switch (Reliance Q310C) to power my service panel using a portable generator. I picked this particular transfer switch as it uses 10 standard 1" Cultler Hammer BR breakers that are user replaceable and configurable. My service panel is pretty simply set up. There are only 13 single pole circuits of either 15 or 20 amps for the entire house. No 240V circuits at all. Tonight, I pulled the front of the service panel off to survey the job. The only glitch is that I noticed one particular breaker has a red wire attached to it instead of black like all the others. Some research on my part turned up the fact that this breaker (20 amp) and the breaker directly above it (20 amp with black wire) are part of what I learned is a "multiwire branch circuit" that feeds a utility outlet in my laundry room, as well as an outlet in my kitchen. Both breakers share a single white neutral at the service panel. Further reading of a downloaded install manual for the Reliance Q310C produced this warning:

"If a selected circuit is part of a multiwire branch circuit, ensure the other branch circuit that shares the neutral is also connected to the transfer switch. The two circuits must be connected to opposing legs (phases) of the generator power and a handle tie must be installed on the switch handles so that both legs are transferred at the same time."

I understand the reason for this is so there is no risk of overloading the shared neutral. I understand how to physically wire the transfer switch into the service panel. I also understand that two adjacent positions (eg. A and B) on the transfer switch will represent the required opposite phases of the generator producing the emergency power (see attached photo link below).

So...just so I can get this straight in my head... I put the two breakers that represent the multiwire branch circuit from the service panel on the transfer switch in say, positions A and B. This will ensure that they are each on opposing legs of the generator. Then just physically tie them together with the handles Reliance provides? I will be doing this to the part of the transfer switch that is marked GEN-OFF-LINE right? That way you either have them both on or both off. Most important to me is to ask, if I have this all down correctly?...then after that, how exactly can a shared neutral be potentially dangerous if hooked up to the transfer switch improperly? Thanks!

Bob

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#13 ·
To be honest, with the size of the panel and the number of breakers in the panel, I'd be tempted to eliminate the Reliance panel all together if I could find an approved interlock kit.
 
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#2 ·
You stated that the MWBC (Multi-Wire Branch Circuit) powers a outlet in the Kitchen, and a outlet in the laundry area. Are they right next to each other, or is the laundry area in the basement or garage?

Update with your location in your profile. Also how old is this place, because it is odd that you do not have a 240Vac for a dryer or Central A/C, etc.. Post a picture of the current panel with the dead front off, and the sticker if it is correct, showing what breakers are for what circuits.

Also, what generator are you planning on using with the Transfer panel, what circuits do you plan on powering during a outage?
 
#3 ·
You stated that the MWBC (Multi-Wire Branch Circuit) powers a outlet in the Kitchen, and a outlet in the laundry area. Are they right next to each other, or is the laundry area in the basement or garage?
Laundry area is in the basement right next to the room where the service panel is. The kitchen is directly above the laundry room on the first floor.

Update with your location in your profile.
I will as soon as I figure this new forum out. I live in NY.

Also how old is this place, because it is odd that you do not have a 240Vac for a dryer or Central A/C, etc..
House was built in 1933. Dryer and Washer are 120VAC and coexist nicely on the same circuit. Service panel was upgraded from fuses to breakers and 200amp service in the 1970's. Initiated by my father in law. He used a local company that was pretty well respected. I wasn't married to his daughter yet and he's dead now, so that's all I can tell you.

Also, what generator are you planning on using with the Transfer panel, what circuits do you plan on powering during a outage?
Generac XP 8000E (8000 running 10,000 surge). I plan wiring in circuits 1, 2, 3, 5, 7, 8, 9, 10, 11, 13. The multibranch circuit is 9 and 11. I will post a front panel shot soon so these numbers make sense.
 
#4 ·


Breaker # are light blue
20 Amp = orange dots on the switches. All others 15 amps
All are single pole

1-Bedroom and dining room A/C outlets
2-Dishwasher
3-Bedroom and bathroom lights
4-Hall lights
5-Den, garage, guest bedroom lights
6-Laundry room lights
7-Refrigerator
8-Oil burner
9-Washer/Dryer
10-Basement/Kitchen lights/sump pump
11-Microwave oven outlet
12-Some kitchen and dining room lights
13-Living room A/C outlet
 
#5 ·
If I am not mistaken, looks like some of that wiring may be Aluminum, but could be tinned Copper, due to being rubber with clothe covering jacket. As for the MWBC, especially for the Kitchen, they are better meant to be used in that same space, than split between the Kitchen & Laundry. Especially if you have two gfci outlets on that circuit, they could in theory wreck havoc on each other, causing nuisance trips, if one senses a problem say in the kitchen, which can cause the laundry to trip, and vice versa.

Getting back to the basics, find out a load calculation of what all you want running. How many lights in the place, what essentials (ie Sump pump, Kitchen, Living Room, bedroom, bath, basement lights). As for the Oil Burner & A/C, what is the info on the plates for amps and/or watts and volts for those items? You could get by with some creative use of the a/c's during the summer, by only using one, then say when you go to bed, use the other, shut off the Living room.

The Load calc will help to find out how much room you have, before you put too much load on the genset.
 
#6 ·
If I am not mistaken, looks like some of that wiring may be Aluminum, but could be tinned Copper, due to being rubber with clothe covering jacket. As for the MWBC, especially for the Kitchen, they are better meant to be used in that same space, than split between the Kitchen & Laundry. Especially if you have two gfci outlets on that circuit, they could in theory wreck havoc on each other, causing nuisance trips, if one senses a problem say in the kitchen, which can cause the laundry to trip, and vice versa.

Getting back to the basics, find out a load calculation of what all you want running. How many lights in the place, what essentials (ie Sump pump, Kitchen, Living Room, bedroom, bath, basement lights). As for the Oil Burner & A/C, what is the info on the plates for amps and/or watts and volts for those items? You could get by with some creative use of the a/c's during the summer, by only using one, then say when you go to bed, use the other, shut off the Living room.

The Load calc will help to find out how much room you have, before you put too much load on the genset.
 
#7 ·
No not a shred of aluminum in those wires. All copper. No GFI outlets either. Were old school here. :laughing: Actually did all the load balancing work already...just was wondering about my 2 questions in my opening post regarding if linking of A and B in the transfer switch selector is correct and some history on shared neutrals.
 
#11 ·
Even in 1933 the kitchen would have had TWO 20A small appliance circuits.
Those were probably #9 and #11. The Laundry should have it's own 20A circuit.

Fix that. Separate the laundry from the upstairs kitchen... put it on it's own circuit.
THEN see if the SA circuits are still a MWBC. I doubt they are.
 
#19 ·
I guess what I find the confusing point (and I totally blame myself for this) is it seems you are saying I need a handle tie on the breakers in position A & B for both the circuit breakers and the Gen-Off-ON part of the transfer switch.

I'm thinking since the shared neutral circuit breakers in the service panel are not tied together...then that configuration should be duplicated in the transfer switch...two separate A & B breakers (no ties) below and the Gen-Off-Line switch above (A & B position) is the only part handle tied.

If I am wrong here please explain why so I can get a clearer understanding.
Thanks,
Bob
 
#18 ·
If you have a panel with multiple small transfer switches and you connect up a multiwire branch circuit to two of those little transfer switches and one of them is set to generator power and the other is set to utility power and there is a 240 volt appliance on the MWBC then it is possible to feed generator power up into the utility lines.
 
#20 ·
The purpose of the handle tie for the panel breaker for the multiwire branch circuit is so that someone working on the circuit does not flip off one breaker and forget to flip off the other and the work area and neutral are still live.
 
#24 ·
Another off subject...(sorry) What exactly are those cloth-covered conductors in the panel? With the house being from 1933 I was thinking knob and tube, but I see both black and white wires.

Also, I don't know that much about transfer switches, but I would think that you would need to use a handle-tie for the two MWBC breakers, that way both would always be on either generator or utility power at the same time. Is this correct or am I totally off?
 
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