Breaker Panel Question regarding voltage

[Semiahmoo]

Have a 1978 37c

Voltage coming into the main shore power breaker panel reads 118v.

Voltage on each side of breaker panel reads 110v.

Voltage at outlets also read 110v.

Is it normal to have a drop from 118v coming in to 110v going out?

I know Hatteras of this era were 110v systems so thinking I'm fine but thought I should ask to make sure. Thanks for any insight.

 

[Captain Ralph]

How are you measuring your voltage levels? Same real meter?
Loaded/unloaded?

 

[Semiahmoo]

How are you measuring your voltage levels? Same real meter?
Loaded/unloaded?

W/O load the voltage to the panel reads 120v. If I turn on something like the salon heat pump unit it drops to 118v and shows amp usage of 15 amps or so.

Outlets read 110v regardless.

 

[Captain Ralph]

I read a voltage drop concern in your typing.
I'm assuming single 30A service.
2 volt drop after a 15 amp load, really not to bad..
Your concern been building up or recently while running the ACs 24x7?

What single meter are you using? Fluke, radio shack, harbor fright ??

Measured the dock supply voltage yet?

First place to look, because it is usually the problem,, do the 30A shore power cord connects look brand new? not warm? not melted or deformed in the cable end and in the hull connect and dock outlet ???

Oh, to make sure, I also assume you do not have an isolation transformer,, rite ??

 

[Semiahmoo]

I read a voltage drop concern in your typing.
I'm assuming single 30A service.
2 volt drop after a 15 amp load, really not to bad..
Your concern been building up or recently while running the ACs 24x7?

What single meter are you using? Fluke, radio shack, harbor fright ??

Measured the dock supply voltage yet?

First place to look, because it is usually the problem,, do the 30A shore power cord connects look brand new? not warm? not melted or deformed in the cable end and in the hull connect and dock outlet ???

Oh, to make sure, I also assume you do not have an isolation transformer,, rite ??

I'm not worried about the minor voltage drop showing on the panel when running the heat pump. I'm wondering if it's normal to have 120v coming into the panel and 110v showing at the outlets.

Electrical certainly is not my area of expertise.

 

[Avenger]

Is it possible that your boat has an isolation, or polarization transformer? I would think it was too small or too early for Hatt to be installing them, but I would check. Do you have the factory manual? It should have a schematic.

 

[Bob Quinn]

 

[Bob Quinn]

I posted that pic with a voltage drop calculator screen shot. even at full load, voltage drop should be less than a 2 volts. This is assuming 14 gauge copper wire 30 ft run etc.

One other thing to check: Check both sides of the incoming voltage. You could have 120 on one phase and 110 on the other. If your checking one incoming phase at the panel, but the other at the plug it could lead you to the conclusion that you have a voltage drop.

Check both legs at the dock too.

I used to do a lot of home electrical work and it was not uncommon to find loose screws at plugs in older houses. All the wiggling of plugging in and unplugging stuff tends to make screws loosen up.

I'm assuming our boats are all copper wiring. There was a point in time, I think in the 70's when people started using aluminum wires to save money. Aluminum doesn't tighten down well and tends to loosen up. To this day they still use aluminum for the wires coming from the outside meters to the main breakers in the breaker panels. I doubt there is any aluminum in our Hat's.

The point is to check all screws at the outlets and on the breakers and on the mains coming in.
---- with the power off of course! ----

The plugs on our long power cords are not ideal ways of getting 50 amps into a boat, they connection just are not tied down very tight which makes them susceptible to any corrosion or wear in the outlets to create a weak point / poor connection situation.

Also copper can get corrosion on the connection points too. I'm guessing this is more common in salt water environments. So the wires might be worth a close inspection.

When I was wiring houses we always used a black anti-corrosion paste on the ends of the aluminum wires that fed the main breakers in the breaker panels. It probably wouldn't hurt if this same anti-corrosion paste was used on all copper connections, but I doubt they did that.

Wires themselves typically don't degrade, its 99.9% of the time an issue at the connection.
One caveat here, if it is stranded wire, then theoretically salt water, if applied to the end of the wire, could seep up into a wire and rot out each individual strand somewhere up inside a cable.

Captain Ralph I'm sure know if we have solid or stranded wire I'm thinking its stranded.
Residential houses all use solid wire.

New quality plugs might even be in order after 30 or 40 years of use.
The internals where the plugs make contact could be worn. Not that this would affect your meter reading but could affect actual connection to your appliances.

If you are truly getting a 10 volt drop (on the same phase) between panel and outlet then something is amiss.

Just a guess: you might have one incoming leg at 110, the other at 118 coming in on your shore line.



Correction the paste is not called anti corrosion, it is called anti-oxidation paste. But same difference.

 

[Pascal]

Marine wiring is ALWAYS stranded wires, never solid like in a house. Nowadays it should all be tinned to prevent corrosion but back in the 70s it was just plain copper.

It s hard to offer any suggestion not knowing how the voltage is measured. Are you using the original analog meter on the panel, a quality multimeter or some Chinese made radio shack $10 meter…

Some voltage drop is normal even with everything new. As components age though it will get worst and everything adds up so it may not be a single issue. Could even be the dockside receptacle or wiring on the pedestal. Or the shore power cable and boat inlet. Or the old fashioned fuses near the inlet if you have them..

First thing I d do besides measuring with a quality meter is look for sign of heat under load. And IR thermometer comes in handy for this but feeling the shore power plugs AND the cable thru its entire length is a good start. I once had a 50 amp cord fail about 15 feet from the end. About 3 or 4’ of it was hotter than the rest

 

[Bob Quinn]

What Pascal said LOL, pretty much nailed it. i.e. don't compare what the 40 year old panel meter says to a handheld. Even though a cheap meter isn't the best idea, it should show relative differences o.k. (I would think) but might not be accurate to within better than 5 or 10%

I like the infra red meter idea, good call!

 

[Semiahmoo]

Update: My boatyard is suggesting replacing the panel due to the 10 volt difference between incoming (120v) and the 110v outgoing they measured on both sides of the panel and all the outlets.

Dang.

 

[Bob Quinn]

Update: My boatyard is suggesting replacing the panel due to the 10 volt difference between incoming (120v) and the 110v outgoing they measured on both sides of the panel and all the outlets.

Dang.

I would just go through and check for loose connections, and possible corrosion at the connections.
The only thing a new panel would do is give you a panel with tight connections.

Are all your outlets showing 110 and you have 120 on both phases on the incoming power at the panel? (checked with same voltmeter)?

 

[Semiahmoo]

I would just go through and check for loose connections, and possible corrosion at the connections.
The only thing a new panel would do is give you a panel with tight connections.

Are all your outlets showing 110 and you have 120 on both phases on the incoming power at the panel? (checked with same voltmeter)?

Correct - 120v incoming at panel and 110v going out and at outlets.

Will discuss with service manager regarding checking connections, etc.

 

[Pascal]

Of course they want to replace the whole panel…. $$$$$$$$$$

Post pictures of the panel, outside and also inside so we can see if it s been butchered over the years.

What shore power do you have, 120/ 30 amp or 120-250/50?

Originally my boat had a big terminal strip next to the panel in the ER feeding many loads incl 120v. Had a bunch of corrosion there as well. One day I opened up my panel in the dark after the light failed in the port ER, and as i swung it open I saw a bunch of arcing inside a panel. Loose connections and corrosion. That’s when I decided to rewire everything and set up a new panel

 

[Semiahmoo]

Of course they want to replace the whole panel…. $$$$$$$$$$

Post pictures of the panel, outside and also inside so we can see if it s been butchered over the years.

What shore power do you have, 120/ 30 amp or 120-250/50?

Originally my boat had a big terminal strip next to the panel in the ER feeding many loads incl 120v. Had a bunch of corrosion there as well. One day I opened up my panel in the dark after the light failed in the port ER, and as i swung it open I saw a bunch of arcing inside a panel. Loose connections and corrosion. That’s when I decided to rewire everything and set up a new panel

It's 120/30 amp with the two 30 amp connections coming into the boat.

Yes, I'm going to look over the panel internals more carefully this week. I hate taking out original Hatteras equipment as it's so well made. Would rather clean it up if possible vs tearing it out and replacing with new.

 

[Bob Quinn]

And cleaning it up checking connections cost will be what, about 1/100th the cost of a new panel!

 

[jim rosenthal]

If you aren't using a good quality meter like a Fluke, I owuld start with that. (mine came packaged with a IR thermometer which has been equally useful)
Aluminum wire was not used on boats. All marine wiring is stranded copper, but tinned stranded copper came along a bit later.

I'd begin by checking all the connections, starting with the power at the dock, and going stepwise through everything, taking notes as you go. I suspect you'll find a poor connection someplace. The shore power cables get blamed often (and deservedly so) but wiring can deteriorate or become loose inside the boat as well.

As said, the plug-and-receptacle system used on boats of our sizes isn't ideal. If you look at bigger yachts with 100 amp service they have serious plugs and receptacles that are more up to the job.

 

[jim rosenthal]

Update: My boatyard is suggesting replacing the panel due to the 10 volt difference between incoming (120v) and the 110v outgoing they measured on both sides of the panel and all the outlets.

Dang.

First figure out where the voltage drop is located. Hatteras Yachts was one of the few boat builders who had an in-house electrical shop that built all their panels. The wiring and panels are very well made. There's a good chance that yours may be fine, or just need a few small components or connections serviced or replaced.

 

[Pascal]

They’re only so much you can do to clean up an old panel. After 40 years there may be some arcing in some of the breaker terminals or inside the breakers as well. Pulling each wire out of each breaker and checking for arcing marks is probably the only option. Time consuming

 

[sixty]

My 78 is all stranded and tinned wire from the factory. way better quality than whats available today. I salvage the cable whenever I abandon a new circuit and re use. 45 years later it still works great.no need to replace the panel, if its the same problem after all of the breakers it can pnly be the main connection which should be simple to diagnose. the workers just want to throw parts at it.