Interlock vs. throwing the main circuit breaker for generator powering a house

ultrarunner

Super Star Member
Joined
Apr 6, 2004
Messages
18,147
Location
SF Bay Area-Ca Olympia WA Salzburg Austria
Tractor
Cat D3, Deere 110 TLB, Kubota BX23 and L3800 and RTV900 with restored 1948 Deere M, 1949 Farmall Cub, 1953 Ford Jubliee and 1957 Ford 740 Row Crop, Craftsman Mower, Deere 350C Dozer 50 assorted vehicles from 1905 to 2006
User Error cannot be underestimated...

Ever hook up Jumper Cables reversed or tried to start a car and the engine was already running?

A good system has fail safe.
 
Last edited:

Oldoak

Veteran Member
Joined
Feb 20, 2013
Messages
1,810
Tractor
Kubota L5060GST, J D X758 GT, J D 855D XUV
An interlock is an acceptable alternative to a transfer switch in some areas. Stating an interlock is the safest device is not valid. A transfer switch is a complete, positive disconnect from the power grid.

Why a Generator Needs a Transfer Switch
As was stated in a prior post, an interlock is the safest between the two options the O.P. was inquiring about.
 

TheMan419

Veteran Member
Joined
Dec 6, 2015
Messages
2,206
Location
Indiana
Tractor
New Holland Boomer 24
Cannot imagine installing a generator that is just back fed. We went w the sub panel. It has two switches that cannot both be on at the same time.

Wife thought this made the most sense to her for operating if I were not home. Same reason generator has electric start.
 

LouNY

Super Member
Joined
Jul 4, 2015
Messages
7,090
Location
Greenwich, NY
Tractor
Branson 8050, IH 574, Oliver 1550 Diesel Utility (traded in on Branson)
A legitamate transfer switch interrupts the neutral bond to the electrical grid. Opening a circuit breaker does not. That is a huge safety concern for utility personnel and a major reason that most codes require a transfer switch.

I haven't installed a new transfer switch in 20 years or so,
at that time they were double throw 2 pole devices, the
neutral was not switched or disconnected and they where done to code.
 

marchanna

Gold Member
Joined
May 5, 2017
Messages
483
Location
Pictou County, NS, Canada
Tractor
Kioti DS4110, Kubota GR2120
Funny we’re talking about this. My power just went out and I had to fire up the generator. I don’t have a lot of gas, so no non-essentials. Fortunately, we’re having a heat wave relatively speaking, so I probably don’t have to burn wood for heat.
 

RickB

Super Star Member
Joined
Sep 18, 2000
Messages
15,206
Location
Up the road from Dollar General WNC
Tractor
Just a Scag
I haven't installed a new transfer switch in 20 years or so,
at that time they were double throw 2 pole devices, the
neutral was not switched or disconnected and they where done to code.

The one I had installed in NY was a three pole double pole switch and the neutral was switched to the generator feed.
 

kenmac

Super Member
Joined
Feb 13, 2005
Messages
9,307
Location
The Heart of Dixie
Tractor
McCormick CX105 Kubota MX 5100 HST, Kubota ZD1021, Kawsaki Mule 4010 trans 4x4
I have a 400 amp service to the house. My shop 200 ft from the house is fed from one of the 200 amp breaker boxes at the house. Interlock wouldn't work in my application. I have to turn off both breakers and some of the other 220 breakers.
The power company here assumes people will have generators connected, so they work an outage with that in mind
 

aczlan

Super Star Member
Joined
Mar 7, 2008
Messages
17,758
Location
Northern Fingerlakes region of NY, USA
Tractor
Case 480F LL, Kubota L3830GST, B7500HST, BX2660
I do not. The few transfer switches I have stuck my head inside all did disconnect the grid neutral. I do not know electrical code and have avoided claiming that I do.
IIRC, IF you switch the neutral, it has to be bonded to ground in the generator and upstream of the transfer switch. If you do NOT switch neutral, you CANNOT have the ground and neutral bonded at the generator.

Aaron Z
 
 
Top