Dual Circuit Water Heater - Disconnect Switch

D

designer82

Senior Member
Location
Boston
I have a dual circuit water heater. Please see vendor's wiring diagram in link below.
I'm not sure how to do the local disconnect. 2 different disconnects (one for each circuit) or 1 disconnect that is like double pole, double throw type of deal?

Appreciate your feedback


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wiring schematic — Postimages

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If I’m understanding your wiring diagram correctly, it appears there is a 240V circuit, and a 120/240, so a 2 pole disconnect wouldn’t work.

You’ll need two disconnects grouped together and labeled.
 
Seven-Delta-FortyOne said:
If I’m understanding your wiring diagram correctly, it appears there is a 240V circuit, and a 120/240, so a 2 pole disconnect wouldn’t work.

You’ll need two disconnects grouped together and labeled.
Click to expand...
One power source shows L1, L2 & EGC. The second power source just shows L1 & L2

2 disconnects can be used or a feeder can be ran to a small 4 circuit load center.
 
curt swartz said:
One power source shows L1, L2 & EGC. The second power source just shows L1 & L2

2 disconnects can be used or a feeder can be ran to a small 4 circuit load center.
Click to expand...
I like the single feeder, local 4 circuit load center idea. Cost effective.
Do you know if there's a requirement for a handle tie (for the two double pole breakers) for such an application?
 
Handle tie is not required but 225.30 has requirements for multiple circuits to one appliance.
 
infinity said:
Does anyone make a 4-pole switch?
Click to expand...
Everybody does. We just don't use them much. Don't expect them to be on the shelf anywhere though...
Eaton:
Siemens:
Square D:

I did a bunch of work in commercial solar for a while, we used them for the 600VDC circuits, because to get to 600VDC, you had to loop back one pole of the DC through 3 contacts in series (plus disconnect the other pole).
 
What you have fits description of a MWBC even though larger than most. That would require meeting 210.4(B) that disconnects all ungrounded conductors. Had one that required 120A from 3- 40A 2 pole breakers, had to handle tie all 3. Breakers within sight of heater so used as disconnect.
 
Fred B said:
What you have fits description of a MWBC even though larger than most. That would require meeting 210.4(B) that disconnects all ungrounded conductors. Had one that required 120A from 3- 40A 2 pole breakers, had to handle tie all 3. Breakers within sight of heater so used as disconnect.
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Look at the definition of a multi-wire circuit. Two, 2-wire circuits does not meet the definition.
 
Even if there were multiple MWBC's feeding the equipment the simultaneous disconnect rule for MWBC's would only apply to each set of circuits sharing a neutral.
 
infinity said:
Even if there were multiple MWBC's feeding the equipment the simultaneous disconnect rule for MWBC's would only apply to each set of circuits sharing a neutral.
Click to expand...
So I guess the inspector that said I needed a handle tie was wrong.
Looked at the definition and I missed that it said "AND" a neutral.
 
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Square D catalog has four and six pole safety switches. Both fused and non fused, but only in 600 volt class. six pole is only in 100 and 200 amp versions and apparently only in type 12 and 4x enclosures. Likely a lead time from most suppliers and probably a nice price tag.
 
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