240v reading

Old 06-08-20, 05:33 PM
Thread Starter
Join Date: Jun 2020
Posts: 1
Upvotes: 0
Received 0 Upvotes on 0 Posts
240v reading

does anyone know why I have 240v reading after the meter but not at the bus bars I checked line 1 and line 2 they both read 120 but not 240 inside the panel
Old 06-08-20, 05:35 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 13,923
Received 177 Upvotes on 155 Posts
Where did you take the readings? Did you cycle any breakers?
Old 06-08-20, 05:51 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: United States
Posts: 14,095
Received 786 Upvotes on 666 Posts
They read 120 volts to ground because you have a two-pole breaker that is on. You are reading through a 240v load like a water heater. If you turn off all the two-pole branch circuit breakers you will find out you have one leg that is not hot.
Old 06-08-20, 06:29 PM
Join Date: Sep 2019
Location: Canada
Posts: 1,906
Received 281 Upvotes on 252 Posts
Not sure what you re reading but here is how it works.

Basically you have two 120 volt supplies when measured to Neutral.
So L1 to Neutral = 120 volts and L2 to Neutral = 120 volts.
But the two supplies are 180 degrees out of phase.
So when L1 is at -120 volts, L2 is at +120 volts.
Therefore L1 to L2 = 240 volts
Old 06-08-20, 06:36 PM
Join Date: Sep 2002
Location: welland ontario
Posts: 7,986
Received 500 Upvotes on 410 Posts
Somewhere between where you are reading 240 volts and the bus bars yo have an open hot connection.
Old 06-09-20, 10:10 AM
CasualJoe's Avatar
Join Date: Jan 2010
Location: United States
Posts: 9,827
Received 178 Upvotes on 161 Posts
Check voltages on line side of main breaker, then at buss bars on the load side of main breaker. Cycle the main breaker and check again.

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: