What size transfer switch do I need?

The switch is sized to your electrical service, not to your generator. A 200 amp service takes a 200 amp switch regardless of whether the generator behind it is 13kW or 20kW. We confirm your service size at the site survey before specifying one.

What is a service-entrance rated transfer switch?

A service-entrance rated switch includes the main disconnect, so it can replace your existing main service disconnect rather than sit downstream of it. That often simplifies installation and reduces panel rework, though whether it is permitted depends on your meter configuration and local code.

100A to 600A · every price published

Cummins automatic transfer switches

Q: Do I need a transfer switch with my generator?

Yes. A standby generator cannot be legally or safely connected without one. The transfer switch isolates your house from the utility before the generator energises anything, which is what prevents the generator from back-feeding the line a utility crew may be working on.

38 configurations across 10 families, from $787.04. The transfer switch is what makes a standby generator safe and legal — it isolates your house from the utility before the generator energises anything, so it can never back-feed the line a crew is working on.

Size the switch to your service, not your generator. A 200 amp service takes a 200 amp switch whether the generator behind it is 13kW or 20kW. Ordering to the generator is the most common and most expensive mistake on these jobs, which is why we confirm your service size at the survey before specifying anything.

Cummins OTEC automatic transfer switch with the cabinet door open — Cummins manufacturer photography.

Residential — RA and RSS

Single phase, 240V, aluminum NEMA 3R cabinets that mount outdoors next to the meter. RA is the standard pairing for air-cooled Cummins home standby units and is available service-entrance rated. RSS is non-service-entrance, for when the existing main stays put.

RA 100A

Service-entrance rated available. 4 configurations.

From

$787.04

RSS100 100A

Non-service entrance. 1 configuration.

From

$1,319.15

RA 150A

Service-entrance rated available. 1 configuration.

From

$1,260.78

RA 200A

Service-entrance rated available. 3 configurations.

From

$1,006.58

RSS200 200A

Non-service entrance. 1 configuration.

From

$1,416.43

RA 400A

Service-entrance rated available. 2 configurations.

From

$2,292.46

Commercial — OTEC

Open-transition commercial switchgear, 125A to 600A, single and three phase, 208V through 480V, in indoor Type 1 or outdoor NEMA 3R enclosures.

OTEC 125A

208V, 480V · 3Ph · 4 configurations

From

$2,927.10

OTEC 225A

208V, 480V, 240V · 3Ph, 1Ph · 5 configurations

From

$3,749.76

OTEC 400A

208V, 240V, 480V · 3Ph, 1Ph · 8 configurations

From

$5,021.81

OTEC 600A

208V, 240V, 480V · 3Ph, 1Ph · 8 configurations

From

$8,545.17

Every configuration and price

Model	Amps	Rating	Voltage	Phase	Cabinet	Part	Price
RA	100	Non-SE	240V	1Ph	1	A051C991	$787.04
RA	100	Non-SE	240V	1Ph	3R-Alum	A064G345	$967.39
RA	100	Service entrance	240V	1Ph	3R-Alum	A064G545	$1,189.63
RA CSA	100	Service entrance	240V	1Ph	3R-Alum	A067J404	$1,646.44
RA	150	Service entrance	240V	1Ph	3R-Alum	A066V485	$1,260.78
RA	200	Non-SE	240V	1Ph	3R - Alum.	A064G376	$1,006.58
RA	200	Service entrance	240V	1Ph	3R - Alum.	A064G549	$1,131.88
RA CSA	200	Service entrance	240V	1Ph	3R - Alum.	A067J405	$1,559.40
RA	400	Non-SE	240V	1Ph	3R	A050W633	$2,292.46
RA CSA	400	Service entrance	240V	1Ph	3R - Alum.	A066W927	$4,299.64
RA ACCY	All	—	240V	1Ph	n/a	A076C684	$221.11
RSS100	100	Non-SE	240V	1Ph	3R	A065M392	$1,319.15
RSS200	200	Non-SE	240V	1Ph	3R	A065M393	$1,416.43
OTEC	125	Non-SE	208V	3Ph	1	A075F123	$2,927.10
OTEC	125	Non-SE	208V	3Ph	3R	A075F124	$3,904.87
OTEC	125	Non-SE	480V	3Ph	1	A075F125	$2,927.10
OTEC	125	Non-SE	480V	3Ph	3R	A075F126	$3,904.87
OTEC	225	Non-SE	208V	3Ph	1	A075F135	$3,749.76
OTEC	225	Non-SE	208V	3Ph	3R	A075F136	$4,733.76
OTEC	225	Non-SE	480V	3Ph	1	A075F137	$3,749.76
OTEC	225	Non-SE	480V	3Ph	3R	A075F138	$4,733.76
OTEC	225	Service entrance	240V	1Ph	3R	A075N276	$8,075.49
OTEC	400	Non-SE	208V	3Ph	1	A075F127	$5,021.81
OTEC	400	Non-SE	240V	3Ph	1	A075F128	$5,021.81
OTEC	400	Non-SE	480V	3Ph	1	A075F129	$5,021.81
OTEC	400	Non-SE	208V	3Ph	3R	A075F130	$6,302.96
OTEC	400	Non-SE	240V	3Ph	3R	A075F131	$6,302.96
OTEC	400	Non-SE	480V	3Ph	3R	A075F132	$6,302.96
OTEC	400	Non-SE	240V	1Ph	1	A075F133	$5,021.81
OTEC	400	Non-SE	240V	1Ph	3R	A075F134	$6,302.96
OTEC	600	Non-SE	208V	3Ph	1	A075F139	$8,545.17
OTEC	600	Non-SE	240V	3Ph	1	A075F140	$8,545.17
OTEC	600	Non-SE	480V	3Ph	1	A075F141	$8,545.17
OTEC	600	Non-SE	208V	3Ph	3R	A075F142	$9,826.31
OTEC	600	Non-SE	240V	3Ph	3R	A075F143	$9,826.31
OTEC	600	Non-SE	480V	3Ph	3R	A075F144	$9,826.31
OTEC	600	Non-SE	240V	1Ph	1	A075F145	$8,545.17
OTEC	600	Non-SE	240V	1Ph	3R	A075F146	$9,826.31

RA accessory kit (part A076C684) — $221.11.

Equipment only. Installation quoted with your generator after a site survey.

What it is for

The switch that makes backup power automatic

A generator with no transfer switch is a machine someone has to be at home to start, and connecting one without a switch backfeeds the utility line and endangers the crews working to restore it. The switch is what makes the whole thing legal, safe and automatic.

Why it becomes urgent

It is sized to the electrical service rather than to the generator, which is the detail most competing quotes get wrong.

Who buys it

Every permanently installed standby generator, residential or commercial.

These are installed across the Dallas–Fort Worth Metroplex by our own licensed crews — the cities we serve, what installation involves, and a free on-site survey before any number is put in writing.