Thread: Grounding at water heater

I inspected a 11 unit apartment complex built in 1969. The units are supplied by (2) 400 amp fused disconnects located at a utility closet (pic#1). Each unit has a 125 amp Cutler Hammer panel(pic#3) however the main disconnects are also located in the utility closet(pic#1). The branch circuits are via conduit. I specialize in residential and don't do a whole lot of apartments or conduit so I have a few questions on this set up. First lets get the Zinsco out of the way. The 400 amp mains and 125 amp disconnects are all Zinsco. I have informed the client of the dangers and referred it to a specialist. My first question is 6 or less moves to kill power. Is that required inside the units or does the disconnect at the utility closet make it ok? Second is the grounding at the water heaters. No grounding conductor is supplied to any of the water heaters(pic#4) . Does the conduit act as a ground here or should one be installed? Also no bonding jumpers at the water heater. I did find bonding to the plumbing system inside one of the units (pic#5). Is this acceptable or should jumpers be at every water heater? Thanks in advance for your comments.

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Originally Posted by Bill Anglin

I inspected a 11 unit apartment complex built in 1969. The units are supplied by (2) 400 amp fused disconnects located at a utility closet (pic#1). Each unit has a 125 amp Cutler Hammer panel(pic#3) however the main disconnects are also located in the utility closet(pic#1). The branch circuits are via conduit. I specialize in residential and don't do a whole lot of apartments or conduit so I have a few questions on this set up. First lets get the Zinsco out of the way. The 400 amp mains and 125 amp disconnects are all Zinsco. I have informed the client of the dangers and referred it to a specialist. My first question is 6 or less moves to kill power. Is that required inside the units or does the disconnect at the utility closet make it ok? Second is the grounding at the water heaters. No grounding conductor is supplied to any of the water heaters(pic#4) . Does the conduit act as a ground here or should one be installed? Also no bonding jumpers at the water heater. I did find bonding to the plumbing system inside one of the units (pic#5). Is this acceptable or should jumpers be at every water heater? Thanks in advance for your comments.

Disjointed questions unrelated to each other.

The units are supplied by main power feeders.

The unit disconnects (green) and the common area building feeder disconnect need to be clearly identified.

The junk storage in the Utility room MUST be removed to an area not within the clearance area/workspace in front of the electrical panels - nothing is allowed to be in the "zone". Is that a sprinkler head up above the junk in front of the meter banks?



The utility room is allowed to be the location of the unit (main power feeder) protection and disconnect. Access must be available to the unit occupants (via unlocked door, via having been provided a key) UNLESS the building is under continuous 24/7 supervision, in that case the utility room may be under restricted (management only) access I can't make out the full schematic on the unit panel you pictured due to the camera angle of the photographer.

Bonded conduit and boxes are a legitimate means for bonding.

The water heater closet has had a closet pole, shelf support and shelf added after the original and inproperly in the dedicated space of the electric resistance water heater.

Your photo of the top of the electric water heater in a unit closet does not support your conclusion regarding the presence or lack thereof of an insulated bonding conductor to the water heater. Can't confirm or deny flexible raceway vs. a cable assembly from the outside, you didn't remove plate. We can't tell if these are 30 gal tall boys (120V) or larger water heaters, or if they are 240 which would use two hots and a grounding/bonding conductor, or 208V.

Since the water heater is supplied with FMC it must have an EGC within or on the outside of the raceway unless it can comply with 250.118(5). (This is from the 2008 NEC). Not sure if any of this applied in 1969 or when the HWH was replaced.

250.118(5) Listed flexible metal conduit meeting all the following conditions:
a. The conduit is terminated in listed fittings.
b. The circuit conductors contained in the conduit are protected by overcurrent devices rated at 20 amperes or less.
c. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible metal conduit in the same ground return path does not exceed 1.8 m (6 ft).
d. Where used to connect equipment where flexibility is necessary after installation, an equipment grounding conductor shall be installed.

Originally Posted by Bill Anglin

My first question is 6 or less moves to kill power. Is that required inside the units or does the disconnect at the utility closet make it ok?

It is OK.

Originally Posted by Bill Anglin

Second is the grounding at the water heaters. No grounding conductor is supplied to any of the water heaters(pic#4) . Does the conduit act as a ground here or should one be installed? Also no bonding jumpers at the water heater. I did find bonding to the plumbing system inside one of the units (pic#5). Is this acceptable or should jumpers be at every water heater? Thanks in advance for your comments.

Not visible, so you could call for further investigation if you suspect a problem.

The size of the circuit breaker is key as to the flex conduit being allowed to be the ground connection. If the circuit breaker is 20 AMPs or less, flex is acceptable as a ground. If the breaker is larger than 20 AMP a separate ground must be used.

I personally wouldn't accept the flex in the picture as having the connector properly installed and the flex appears to be pulled a bit tight due to being short. If the connector can't be screwed all the way into the flex and not be pulled off when installed on the water heater there is an issue

The water heaters are all 30 amp 240v. There are 2 hots and a neutral supplied to the water heaters. It is suspect at the very least and I know the client will be having an electrician in to clean the place up anyway. I will add it to the further evaluate and repair as necessary pile. Thanks guys.

It would be an unusual WH to need a neutral. Most WH are straight 240 with no neutral required.

Power was off to one of the units so I went back and inspected it today(power turned on) I looked a little closer at the water heater and your right. Only two hots. I have a hard time comprehending this though. How can you complete the circuit without a neutral?

Originally Posted by Bill Anglin

Power was off to one of the units so I went back and inspected it today(power turned on) I looked a little closer at the water heater and your right. Only two hots. I have a hard time comprehending this though. How can you complete the circuit without a neutral?

Quite simply, the neutral is the center tap of a transformer. If you label the hot wires (which are both ends of the transformer winding) L1 and L2, and label the center tap of the winding as a neutral, N, then from either L1 or L2 to N you get 120 volts. Between L1 and L2 there is 240 volts

L1_/\/\/\/\/\_N_/\/\/\/\/\_L2

There are two types of appliances found in residences that use 240 volts. One kind will have 240 volt on the label, and only uses L1 and L2. The other kind will have 120/240 volt on the label and uses all 3 wires.

There are also something called multi-wire branch circuits in some places. These are where there are 2 circuits, one on L1 and one on L2 that share a common neutral. In this type of circuit, if the load is exactly the same on each circuit the neutral carries no current (there are circumstances where this doesn't happen, but generally it does). If the loads are different, like one circuit has a 10 AMP load and the other a 5 AMP load, the neutral carries only the difference, or 5 AMPs. People who aren't familiar with this type of circuit can fry things by disconnecting the neutral, or overload the neutral by putting both hot wires on the same line (L1 or L2)

If you're inspecting panels you need to brush up on this stuff. Done wrong it can cause major issues.

Originally Posted by Bill Kriegh

Quite simply, the neutral is the center tap of a transformer. If you label the hot wires (which are both ends of the transformer winding) L1 and L2, and label the center tap of the winding as a neutral, N, then from either L1 or L2 to N you get 120 volts. Between L1 and L2 there is 240 volts

L1_/\/\/\/\/\_N_/\/\/\/\/\_L2

There are two types of appliances found in residences that use 240 volts. One kind will have 240 volt on the label, and only uses L1 and L2. The other kind will have 120/240 volt on the label and uses all 3 wires.

There are also something called multi-wire branch circuits in some places. These are where there are 2 circuits, one on L1 and one on L2 that share a common neutral. In this type of circuit, if the load is exactly the same on each circuit the neutral carries no current (there are circumstances where this doesn't happen, but generally it does). If the loads are different, like one circuit has a 10 AMP load and the other a 5 AMP load, the neutral carries only the difference, or 5 AMPs. People who aren't familiar with this type of circuit can fry things by disconnecting the neutral, or overload the neutral by putting both hot wires on the same line (L1 or L2)

If you're inspecting panels you need to brush up on this stuff. Done wrong it can cause major issues.

I have a very large buldge on disc L1-L2does that count

Originally Posted by Bill Kriegh

Quite simply, the neutral is the center tap of a transformer. If you label the hot wires (which are both ends of the transformer winding) L1 and L2, and label the center tap of the winding as a neutral, N, then from either L1 or L2 to N you get 120 volts. Between L1 and L2 there is 240 volts

L1_/\/\/\/\/\_N_/\/\/\/\/\_L2

There are two types of appliances found in residences that use 240 volts. One kind will have 240 volt on the label, and only uses L1 and L2. The other kind will have 120/240 volt on the label and uses all 3 wires.

There are also something called multi-wire branch circuits in some places. These are where there are 2 circuits, one on L1 and one on L2 that share a common neutral. In this type of circuit, if the load is exactly the same on each circuit the neutral carries no current (there are circumstances where this doesn't happen, but generally it does). If the loads are different, like one circuit has a 10 AMP load and the other a 5 AMP load, the neutral carries only the difference, or 5 AMPs. People who aren't familiar with this type of circuit can fry things by disconnecting the neutral, or overload the neutral by putting both hot wires on the same line (L1 or L2)

If you're inspecting panels you need to brush up on this stuff. Done wrong it can cause major issues.

Nice explanation here by Bill.

In even simpler terms if you had two 1.5 volt batteries connected one end to end (like in a flashlight) and you measured the voltages, (disregaring the polarity) you would have 3 volts at the ends and 1.5 volts from either end to the middle point where they're joined. Same thing would apply to a 1Ø, 120/240 volt circuit. 240 volts from end to end and 120 volts from either end to the middle point.

Originally Posted by Bill Anglin

Power was off to one of the units so I went back and inspected it today(power turned on) I looked a little closer at the water heater and your right. Only two hots. I have a hard time comprehending this though. How can you complete the circuit without a neutral?

Because a rms 240Vac 60 Hz 1~ electric storage type water heater is a purely resistive load. The utilization/working of the true split single phase electricity is balanced, and pure resistance load; 1 tap is 180 degrees from the other tap; and for each half-cycle the other hot conductor (opposes) balances the first. There is no unbalanced current flow or unbalanced voltage, there is no off-timed cycle or overlapping time-wise wave form (e.g. 120 degrees tap), no power factor issues, harmonics, or other issues such as an inductive load might produce, no caps, or electronics either. The electrons move back and forth, they don't move (flow) in one direction as in a DC circuit.

Two hots plus Gnd (bonding), no grounded ("neutral") conductor is necessary when the supply is 240Vac 60 Hz true split single phase for a purely resistive load. If the supply was 208 you'd need a "neutral".

Originally Posted by H.G. Watson, Sr.

Two hots plus Gnd (bonding), no grounded ("neutral") conductor is necessary when the supply is 240Vac 60 Hz true split single phase for a purely resistive load. If the supply was 208 you'd need a "neutral".

Are you saying that a single phase 208 volt HWH would require a neutral and not just a 2-wire + EGC circuit?

Originally Posted by Robert Meier

Are you saying that a single phase 208 volt HWH would require a neutral and not just a 2-wire + EGC circuit?

No "neutral" is ever required for a straight 240V or 208V load (or a 480V load in commercial settings). Just the two hots, tied on to a two pole OC device.

The term "neutral" is only correct in a multi-wire circuit, where the "grounded conductor" (white wire)/(neutral) carries the unbalanced load current of the 2 or 3 "hots".

In a standard 120V 2-wire circuit, the grounded conductor (white wire) is not really a 'neutral", it carries the same amount of current as the "Hot" conductor.

Hope this helps.

Originally Posted by Steve Koszuta

No "neutral" is ever required for a straight 240V or 208V load (or a 480V load in commercial settings). Just the two hots, tied on to a two pole OC device.

The term "neutral" is only correct in a multi-wire circuit, where the "grounded conductor" (white wire)/(neutral) carries the unbalanced load current of the 2 or 3 "hots".

In a standard 120V 2-wire circuit, the grounded conductor (white wire) is not really a 'neutral", it carries the same amount of current as the "Hot" conductor.

Hope this helps.

Careful with the "never". A 240 volt delta connected system with a phase center grounded has a 208 phase-to-neutral voltage (ungrounded phase to neutral). There are other configurations with a grounded conductor at other than a 120 volt-to-phase potential

While "neutral" is only technically correct in a multi-wire circuit it is understood to refer to the grounded conductor in all cases anyway. Regardless what you call it, it ties to a neutral in the panel.

Originally Posted by Bill Kriegh

While "neutral" is only technically correct in a multi-wire circuit it is understood to refer to the grounded conductor in all cases anyway. Regardless what you call it, it ties to a neutral in the panel.

The 2011 NEC attempts to clear up the confusion of when you have a neutral and when you have a grounded conductor. They've added a definition in Article 100 for the term neutral conductor. Now it's clear as day.

Article 100:
Neutral Conductor. The conductor connected to the neutral
point of a system that is intended to carry current under
normal conditions.

Originally Posted by Robert Meier

The 2011 NEC attempts to clear up the confusion of when you have a neutral and when you have a grounded conductor. They've added a definition in Article 100 for the term neutral conductor. Now it's clear as day.

Actually, that definition was added in 2008.

Originally Posted by Bill Kriegh

While "neutral" is only technically correct in a multi-wire circuit it is understood to refer to the grounded conductor in all cases anyway. Regardless what you call it, it ties to a neutral in the panel.

While that is true, there are NEC sections which specifically refer to doing something/not doing something/counting/not counting based on whether a conductor is a "neutral" or is a "grounded conductor".

Originally Posted by Jerry Peck

Actually, that definition was added in 2008.

Yes, you're correct.