# Should the voltage of L1/N and L2/N sum to the same voltage as L1/L2?

#### dmalkokian

##### Member
Should the voltage of L1/N and L2/N sum to the same voltage as L1/L2? I heard it has be a factor of square root of 3

#### infinity

##### Moderator
Staff member
You have to tell us what system is being used? For example single phase 120/240 or 208Y/120?

#### jim dungar

##### Moderator
Staff member
Should the voltage of L1/N and L2/N sum to the same voltage as L1/L2? I heard it has be a factor of square root of 3
Yes, but the two voltages must be added vectorially, not arithmetically.

As infinity said, the √3 comes into play with 3-phase systems.

#### dmalkokian

##### Member
You have to tell us what system is being used? For example single phase 120/240 or 208Y/120?
It’s single phase. L1/N and L2/N was 110v. But L1/L2 was 186v. Just trying to understand the calculation behind it.

#### dmalkokian

##### Member
I was testing by an equipment. The building is on 3phase but the equipment needed only single.

#### roger

##### Moderator
Staff member
It’s single phase. L1/N and L2/N was 110v. But L1/L2 was 186v.
Well if it is in fact single phase you have a problem.

#### infinity

##### Moderator
Staff member
It’s single phase. L1/N and L2/N was 110v. But L1/L2 was 186v. Just trying to understand the calculation behind it.
Are these measured voltages or just numbers from a calculation? If there just from a calculation there is no such thing as 110 volts.

#### roger

##### Moderator
Staff member
I was testing by an equipment. The building is on 3phase but the equipment needed only single.
Ok, you are probably reading the high leg of a wye system.

#### dmalkokian

##### Member
It’s measured in field with a multimeter ( estimated reading but accurate)

#### infinity

##### Moderator
Staff member
So the building is 3 phase 208Y/120. Phase to phase is 120*1.73. The correct voltages should be 120-N, 208 phase to phase.

Staff member

#### dmalkokian

##### Member
We were authorized to test the equipment only. The onsite electricain said that the whole building was receiving 186v.

#### dmalkokian

##### Member
Should the voltage of L1/N and L2/N sum to the same voltage as L1/L2? I heard its a factor of square root of 3

#### infinity

##### Moderator
Staff member
We were authorized to test the equipment only. The onsite electricain said that the whole building was receiving 186v.
Well that's a problem. Was that measurement taken at the service? That would be the only way to determine if the utility was providing the proper voltage.

#### ggunn

##### PE (Electrical), NABCEP certified
As others have said, the sqrt3 only comes into play if it is two legs of a three phase service you are measuring.

#### dmalkokian

##### Member
Yes the equipment wouldn’t function due to under voltage protection. Was just curious on the calculation of getting 186v between L1/L2

#### roger

##### Moderator
Staff member
If there is a 110 - N voltage present you could be seeing around 186.

110 X 1.73 = 190

Have the utility or someone see what is at the service as Infinity said.

#### dmalkokian

##### Member
Where do get 1.73 from?

Staff member

#### infinity

##### Moderator
Staff member
Where do get 1.73 from?
In a 3Ø Wye system the phase angle is 120°. The 1.73 which is the √3 is derived from that angle.